Search

In this paper we demonstrate a high wall-plug efficiency and low threshold current for heterogeneously integrated III-V-on-Silicon distributed feedback (DFB) lasers. Above 12% wall plug efficiency is achieved for a 200 µm long DFB laser diode at 25 °C. Up to two times 6 mW of optical power is coupled into the silicon waveguide and more than 40 dB side-mode suppression ratio is obtained. We also discuss the non-return-to-zero on-off keying modulation at 20 Gb/s and the transmission over a 2 km long optical fiber.

Compared with transistor lasers (TLs), tunnel-junction transistor lasers (TJTLs) are more easily modulated with the voltage across base-collector (BC) junction. In this work, the charge-control model and modified rate equation of TJTLs which includes the Franz-Keldysh effect and direct tunneling is developed. We conduct DC and AC analysis with our model and show that the doping concentration in the BC junction plays a key role in the capability to voltage modulate TJTLs since it affects the junction field. A trade-off between the optical power and capability of the voltage modulation emerges as a concern for designing the doping concentration. We also study the effect of the quantum well (QW) position. The result shows that the QW closer to the BC junction can obtain a higher confinement factor to achieve better output power and modulation bandwidth.

Deep-ultraviolet (Deep-UV) micro light-emitting diodes (Micro-LEDs) array greatly benefits various future applications. In this letter, we fabricated Deep-UV Micro-LEDs with different geometries from 10×10 µm2 to 200× 200 µm2, and investigated its application on tristimulus quantum dots converted display. As the Micro-LEDs scaling, the smaller-sized devices provided higher brightness under the same injection current density due to the enhanced current spreading uniformity and heat dissipation. For a 10×10 µm2 device, the maximal optical power density was up to 185 W/cm2 at 5 kA/cm2, and the peak external quantum efficiency reached 3.43 % at 30 A/cm2. The device exhibited a minor blue shift phenomenon as the current density increased. Deep-UV Micro-LED stimulated quantum dots display obtained 121% of the Rec. 2020 standard in the CIE 1931 color space. This ultra-wide color gamut indicated it as a competitive candidate for future display technology.

Two-dimensional monolayer and few-layer transition-metal dichalcogenides (TMDs) are promising for advanced electronic and photonic applications due to their extraordinary optoelectronic and mechanical properties. However, it has remained challenging to produce high-quality TMD thin films with controlled thickness and desired micropatterns, which are essential for their practical implementation in functional devices. In this work, a self-limiting opto-electrochemical thinning (sOET) technique is developed for on-demand thinning and patterning of TMD flakes at high efficiency. Benefiting from optically enhanced electrochemical reactions, sOET features a low operational optical power density of down to 70 μW μm-2 to avoid photodamage and thermal damage to the thinned TMD flakes. Through selective optical excitation with different laser wavelengths based on the thickness-dependent band gaps of TMD materials, sOET enables precise control over the final thickness of TMD flakes. With the capability of thickness control and site-specific patterning, our sOET offers an effective route to fabricating high-quality TMD materials for a broad range of applications in nanoelectronics, nanomechanics, and nanophotonics.

The quadratic optical nonlinearity arising from two-photon absorption provides the crucial spatial concentration of optical excitation in three-dimensional (3D) laser nanoprinting, with widespread applications in technical and life sciences. Femtosecond lasers allow for obtaining efficient two-photon absorption but are accompanied by a number of issues, including higher-order processes, cost, reliability and size. Here we introduce two-step absorption replacing two-photon absorption as the primary optical excitation process. Under suitable conditions, two-step absorption shows the same quadratic optical nonlinearity as two-photon absorption. We present a photoresist system based on a photoinitiator supporting two-step absorption, a scavenger and a well-established triacrylate. We show that this system allows for printing state-of-the-art 3D nanostructures and beyond. In these experiments, we use ~100 μW optical power from an inexpensive, compact continuous-wave semiconductor laser diode emitting at 405 nm wavelength. Our work opens the door to drastic miniaturization and cost reduction of 3D laser nanoprinters. As an alternative to high-resolution fabrication by two-photon absorption, researchers demonstrate a two-step absorption process that employs inexpensive light sources.

Conventional silica optical fibers can be embedded into composite structures or packaging to provide structural monitoring capabilities. In this paper, the microbending optical losses induced by the packaging of a sensing optical fiber into a sandwiched glass-fiber reinforced structure are investigated experimentally and by simulations. Results show that the positioning of the optical fiber within a plain-weave glass fiber-reinforced structure has a critical effect on microbending optical losses due to potentially induced microdeformations of the optical fiber's cylindrical shape. Similar analysis is also carried out with the use of a 1D glass-fiber layer packaging, demonstrating lower residual microbending losses after manufacturing. By the proper positioning of an optical fiber containing a series of wavelength-multiplexed fiber Bragg grating (FBG) sensors over a 2D plain-weave glass fabric, a 10-fold improvement in the induced optical losses is demonstrated, increasing the optical power that reaches the interrogating unit and allowing the monitoring of hundreds of meters over glass-fiber structures. Although all the analysis is focused and verified using a series of FBG sensors, the results and conclusions related to the induced microbending losses are also valid and useful for distributed optical fiber sensing approaches.

We propose and demonstrate a notch filter on a silicon chip and apply it to a photonic microwave frequency measurement system with high precision and adjustable wide measurement range. The on-chip notch filter is implemented by embedding a serially coupled double microring resonator in a Fabry-Perot cavity consisting of two circular Bragg gratings with high reflectivity. The notch filtering with high quality factor and high rejection ratio is obtained by reconstructing the power transmission spectrum of the double microring resonator through the coherent interference within the Fabry-Perot cavity. The proposed notch filter is fabricated on a silicon-on-insulator wafer and the rejection ratio of the notch filter is measured to be 33.54 dB and the quality factor is 3.93×104. Based on the notch filter, a photonic microwave frequency measurement system is presented where the unknown radio frequency signal is detected by the variation of the output optical power from the notch filter through sweeping reference frequency. The measurement bandwidth of the system can be flexibly adjusted by tuning the output wavelength of the laser source. Broad measurement range of 0-26.62 GHz with a low error of ±0.25 GHz are obtained in a proof-of-concept experiment.

In this paper, we experimentally studied the effects of optical power of semiconductor laser on the electrical properties of silicon diode of an exposed device. The experimental results showed that the laser diode light of different optical powers (2, 3, and 4 mW) had effects on the silicon diode that are somewhat similar to those of thermal treatment. A shift in the current-voltage curve to the left side was also noticed, which led to a non-linear decrease of the barrier voltage of the diode by the effect of laser light. We also reveal a decrease by 344.8 nA/mW in the reverse saturation current of the silicon diode as a result of exposure to laser light. The forward resistance of the silicon diode decreased with increased incident optical power. The value of the maximum current of diode increased by 0.5 A/W with increasing the optical power incident on the diode.

Monolithic high contrast gratings (MHCGs) composed of a one-dimensional grating patterned in a monolithic layer provide up to 100% optical power reflectance and can be fabricated in almost any semiconductor and dielectric material used in modern optoelectronics. MHCGs enable monolithic integration, polarization selectivity, and versatile phase tuning. They can be from 10 to 20 times thinner than distributed Bragg reflectors. The subwavelength dimensions of MHCGs significantly reduce the possibility of ensuring the smoothness of the sidewalls of the MHCG stripes and make precise control of the shape of the MHCG stripe cross-section difficult during the etching process. The question is then whether it is more beneficial to improve the etching methods to obtain a perfect cross-section shape, as assumed by the design, or whether it is possible to find geometrical parameters that enable high optical power reflectance using the shape that a given etching method provides. Here, we present a numerical study supported by the experimental characterization of MHCGs fabricated in various materials using a variety of common surface nanometer-scale shaping methods. We demonstrate that MHCG stripes with an arbitrary cross-section shape can provide optical power reflectance of nearly 100%, which greatly relaxes their fabrication requirements. Moreover, we show that optical power reflectance exceeding 99% with a record spectral bandwidth of more than 20% can be achieved for quasi-Trapezoidal cross-sections of MHCGs. We also show that sidewall corrugations of the MHCG stripes have only a slight impact on MHCG optical power reflectance if the amplitude of the corrugation is less than 16% of the MHCG period. This level of stripe fabrication precision can be achieved using the most current surface etching methods. Our results are significant for the design and production of a variety of photonic devices employing MHCGs. The flexibility with regard to cross-section shape facilitates the reliable fabrication of highly reflective subwavelength grating mirrors. This in turn will enable the manufacture of monolithically integrated high-quality-factor optical micro-and nanocavity devices.

Bi-directional optogenetics at single-cell level requires localized, bright, and multi-color light sources to activate both excitatory and inhibitory opsins. To this end, here we report a simple fabrication method of high-density, two-color, quantum dot (QD) based micron-sized light emitting diode (micro-LED) arrays. In particular, we micro-patterned InP/ZnS QDs on top of GaN-based micro-LED pixels via a simple brushing method, and coated them with a spectral filter. The resulting array featured sub- $20~\mu \text{m}$ sized light spots near both 462 nm and 623 nm, with their optical power density being ca. 0.1 – 1.0 mW/mm2. Combined with its low crosstalk and fast response, our two-color QD-LED array may hold promise for bi-directional optogenetics ultimately at the cellular level.

In this paper, a novel design of a 1×N multimode-interference power splitter is proposed and investigated. By using the finite difference time domain method and particle swarm optimization algorithm, our proposed 1×N optical power splitter can be optimized to realize compact size, good uniformity, low insertion loss, and broad bandwidth. To verify the effectiveness of this design, the designed 1×4 and 1×8 multimode-interference power splitters are experimentally demonstrated on an silicon-on-insulator platform. The lengths of the designed 1×4 and 1×8 power splitters are 36 μm and 47.8 μm, respectively. Experimental results show that, for the fabricated 1×4 power splitter, the uniformity ranges from 0.07 to 0.89 dB and the corresponding maximum insertion loss is 0.62 dB within a bandwidth from 1520 to 1624 nm. For the fabricated 1×8 power splitter, within a bandwidth from 1519 to 1623 nm, the uniformity varies from 0.19 to 0.83 dB and a maximum insertion loss of 0.64 dB are obtained.

SIGNIFICANCE A base-down prism was incorporated on the anterior surface of rigid gas-permeable (RGP) contact lenses to explore potential effects on the residual ocular aberrations after contact lens fitting in keratoconic eyes. PURPOSE This study aimed to evaluate the correction of ocular aberrations with corneal prismatic RGP contact lenses in keratoconic eyes and their impact on visual function. METHODS A cross-sectional and randomized study was performed. Seventeen eyes of 17 keratoconus patients (34.6 ± 11.1 years) were evaluated. Two designs (standard and prismatic) of a corneal RGP contact lens (KAKC; Conoptica, Barcelona, Spain) were fitted to the same eye of each patient in a random order: a standard RGP contact lens as control and a prismatic RGP contact lens with a base-down prism of 1.6 prism diopters. Ocular aberrations were measured for a pupil diameter of 3 mm with and without both contact lenses, whereas high-contrast distance visual acuity, low-contrast distance visual acuity, and contrast sensitivity were measured under photopic and mesopic conditions. RESULTS Both contact lenses improved oblique primary astigmatism, defocus, vertical coma, coma-like, and root-mean-square higher-order aberrations compared with the unaided eyes (P < .05). Furthermore, the prismatic RGP contact lenses offered lower values of vertical coma and root-mean-square higher-order aberrations than the standard RGP contact lenses (P < .05). Both designs (standard and prismatic) produced a positive vertical coma of lower magnitude than the negative vertical coma of the unaided eyes. On the other hand, the improvement achieved in all visual function variables was the same for both contact lens designs (P ≥ .05). CONCLUSIONS The prismatic RGP contact lenses corrected higher levels of higher-order aberrations compared with the standard RGP contact lenses. However, both contact lens designs with the same refractive power were equally efficient at improving visual function.

Single-walled carbon nanotube encapsulated in boron nitrite nanotube (SWCNT@BNNT) is a novel nanomaterial with a one-dimensional van der Waals (1D-vdW) heterostructure. In this paper, we demonstrated that the SWCNT@BNNT has an enhanced optical power tolerance compared to that of the pristine SWCNT while exhibiting an optical saturable absorption properties. Under optical power intensity of 13kW/cm2, the lifetime of the SWCNT@BNNT is found to be 2,270 times longer than SWCNT for 1% degradation in absorbance. A short-cavity mode-locked laser with a high repetition rate of 1 GHz has been realized using the SWCNT@BNNT as the saturable absorber. We have shown that the technique of fabricating nanomaterial with a 1D-vdW heterostructure can modify and enhance the optical properties of the encapsulated nanomaterials., 8 pages, 7 figures

Flexible photodetectors have attracted great attention in fields such as display screens, aerospace, and civil engineering due to their wearable and large-area foldable advantages. Therefore, the hybrid structure of Bismuth oxyselenide(Bi2O2Se)/Graphene was successfully synthesized in this work through mechanical compound method. In addition, we constructed a photodetector based on solid-state electrolyte, which has the advantage of small size, light weight, and portability. Photoelectrochemical tests show that the Bi2O2Se/graphene photodetector based on solid-state electrolyte has excellent photoresponse characteristics under 0 V, and its photocurrent density is 400 nA/cm2 when the optical power is 120 mW/cm2. In addition, the Bi2O2Se/graphene photodetector exhibits superb flexibility. After different bending angles and bending times, the photocurrent slightly decreases, which may be due to small cracks in the bending process. Finally, the tested Bi2O2Se/graphene solid-state photodetector showed excellent stability. The photocurrent was only slightly reduced after 1000 s, which was 81% of the original value. The result shows that the hybrid structure of Bi2O2Se/Graphene has potential in the field of photodetectors with exceptional performance, excellent stability and mechanical properties.

In this paper, a near-infrared “Ge-on-Si” camera with backside illumination, is presented. The camera consists of a photonic chip, a readout chip, and a commercial microcontroller, which is connected to a laptop via USB. The functionality of two-dimensional ( $10\times 10$ pixels) as well as one-dimensional ( $64\times 1$ pixel) “Ge-on-Si” pixel arrays with a pitch of $25~\mu \text{m}$ are demonstrated. The photonic chip consists of basic CMOS technology process in combination with a molecular beam epitaxy growth process. With this technology and the backside illumination a high fill-factor of 74% is achieved. Further the “Ge-on-Si” detectors are operated under zero bias operation in order to minimize the dark current and thus to maximize the signal-to-noise ratio. This enables dark currents better than 100 pA to be achieved in each pixel. A linear behavior between photocurrent and optical power of the “Ge-on-Si” detectors over a large dynamic range for optical powers between 10−7 W and 10−2 W is shown. With relatively thin Ge absorption layers of only 400 nm, optical responsivities of 0.36 A/W at a wavelength of 1310 nm could be achieved. The functionality of the “Ge-on-Si” camera is demonstrated by the movement of a single mode fiber over the photonic chip at a wavelength of 1310 nm.

Laser diode benches (LDBs) with lasing wavelength of 808 nm were developed, manufactured and endurance-tested for utilization as pump lasers for the Nd:YAG oscillator in the climate satellite MERLIN. The LDBs combine customized TE-polarized GaAs-based 5-mm minibars with fast axis collimation lenses to produce a reliable, space qualified component at optical power of 63 W per minibar. Accelerated life tests of 20 LDBs are presented. Except for a small increase in threshold current, no wear out in operating current or sudden failures were observed, and reliable operation over the full mission time of >4 gigashots was confirmed. The electro-optical characteristics remain in the specified ranges after exposure to the total operational load of the mission.

In this article, a novel nonlinear model is proposed to describe the permittivity of the plasma, and the nonlinear optical bistable phenomenon of the 1-D photonic crystals, which is composed of a nonlinear plasma defect layer, is theoretically investigated by the conventional transfer matrix method (TMM) under TM wave. It is figured out that the permittivity of nonlinear plasma exists in bistable state. Then, the tuning effects of the number of the photonic crystals’ (PCs) periodic layers, the incident frequency, the thicknesses of the nonlinear plasma layer, and the incident angle on the optical bistability (OB) have been emphatically studied. Additionally, the transmission and the reflectance under the influences of this bistable tuning are further proposed. The calculated results show that the adjustment of the OB can be achieved without changing the multi-layer material geometry. This multi-composite nonlinear plasma defect structure with the tunable bistable phenomenon can be applied to numerous valuable optical devices, such as novel optical power threshold devices, logic gates, and optical information memory.

Purpose This study aims to focus on roughening N-face (backside) GaN substrate prior to GaN-on-GaN light-emitting diode (LED) growth as an attempt to improve the LED performance. Design/methodology/approach The N-face of GaN substrate was roughened by three different etchants; ammonium hydroxide (NH4OH), a mixture of NH4OH and H2O2 (NH4OH: H2O2) and potassium hydroxide (KOH). Hexagonal pyramids were successfully formed on the surface when the substrate was subjected to the etching in all cases. Findings Under 30 min of etching, the highest density of pyramids was obtained by NH4OH: H2O2 etching, which was 5 × 109 cm–2. The density by KOH and NH4OH etchings was 3.6 × 109 and 5 × 108 cm–2, respectively. At standard operation of current density at 20 A/cm2, the optical power and external quantum efficiency of the LED on the roughened GaN substrate by NH4OH: H2O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts. Originality/value This study demonstrated NH4OH: H2O2 is a new etchant for roughening the N-face GaN substrate. The results showed that such etchant increased the density of the pyramids on the N-face GaN substrate, which subsequently resulted in higher optical power and external quantum efficiency to the LED as compared to KOH and NH4OH.

This manuscript deals with the investigation of the impact of target-to-substrate distance on the linear and nonlinear optical properties of a-plane oriented aluminum-doped ZnO (ZnO:Al) thin films synthesized by the pulsed laser deposition (PLD) technique. X-ray diffraction studies proclaim an increment in the crystallinity with a decrement in target-to-substrate distance from 6 to 3 cm, attributed to increased thickness, decrease in stress, and defect levels in the thin films. A relaxation in the stress induces a decrease in the energy gap (3.47–3.37 eV) with a reduction in target–substrate distance from 6 to 3 cm is observed from UV–visible spectroscopic analysis. Spectroscopic ellipsometry confirms an increment in the refractive index and extinction coefficient with a decrease in target-to-substrate distance. From the Photoluminescence spectrum, the presence of low defect levels in the ZnO:Al thin films prepared at a shorter target-to-substrate distance is observed. The induced absorption (RSA) and self-defocusing process of ZnO:Al thin films are revealed by open aperture and closed aperture Z-scan measurements at 532 nm wavelength. The optical limiting behavior of all the thin films strongly suggests their applicability in optical power limiting. Thus, the present study emphasizes the optimization of the target-to-substrate distance to tailor the structural, linear, and nonlinear optical properties of the a-plane oriented ZnO:Al thin films.

In this study, we report a new type of InGaAs/InP photodetector (PD) with nickel oxide (NiO) transparent p-region and electrode. By applying the NiO film, the device does not require the highly doped p-contact layer and the opaque p-contact metal electrode such as the traditional p-i-n PD. The epitaxial layer of the PD is simplified. Meanwhile, the optical power loss caused by the additional absorption in the highly doped p-contact layer can be avoided. With the fully covered transparent p-contact electrode, the PD can be illuminated from the p-side at the same time. The numerical simulation results show that the new structure can improve the 3-dB bandwidth and the RF output power of the PD.

Silicon nitride (SiN) optical phased arrays (OPAs) have emerged as a potential alternative to their silicon counterparts, owing to their low nonlinearity, easy scalability, and low propagation loss. However, the development of SiN OPAs for light detection and ranging (LiDAR) applications has attracted less attention due to the low thermo–optic (TO) effect of SiN. Moreover, SiN OPAs are considered to be undesirable for transmitters in LiDAR systems because of the limited longitudinal tuning efficiency of SiN grating antenna. We present a hybrid integrated SiN–polymer OPA for realizing an efficient LiDAR. Owing to the large TO effect of polymer, the proposed OPA with polymeric phase modulators resolves the power dissipation drawback of the SiN devices. The polymeric modulators are integrated with a SiN power splitter and grating antenna, and the coupling loss is alleviated via a spot-size converter. Additionally, a steering angle magnifying lens is used to enhance the tuning efficiency of the antenna, expanding the longitudinal beam steering range. The prepared OPA transmitter equipped with the lens exhibits decent two-dimensional beam steering, featuring stable emission characteristics over a 12° × 30° field of view. With the transmitter, efficient time-of-flight based LiDAR is demonstrated to provide a detection range of 10 m under a peak optical power of 55 dBm. The proposed SiN–polymer OPA is highly anticipated to circumvent the challenges of conventional SiN counterparts and potentially spearhead the development of a prominent OPA platform for advanced LiDAR schemes.

Curvy imagers that can adjust their shape are of use in imaging applications that require low optical aberration and tunable focusing power. Existing curvy imagers are either flexible but not compatible with tunable focal surfaces, or stretchable but with low resolution and pixel fill factors. Here, we show that curvy and shape-adaptive imagers with high pixel fill factors can be created by transferring an array of ultrathin silicon optoelectronic pixels with a kirigami design onto curvy surfaces using conformal additive stamp printing. An imager with a 32 × 32-pixel array exhibits a fill factor, before stretching, of 78% and can maintain its electrical performance under 30% biaxial strain. We also develop an adaptive imager that can achieve focused views of objects at different distances by combining a concave-shaped imager printed on a magnetic rubber composite with a tunable lens. Adaptive optical focus is achieved by tuning both the focal length of the lens and the curvature of the imager, allowing far and near objects to be imaged with low aberration. Curvy and shape-adaptive imagers with high pixel fill factors and tunable focusing power can be created by transferring an array of ultrathin silicon optoelectronic pixels with a kirigami design onto curvy surfaces using conformal additive stamp printing.

Lateral separate absorption multi-buffer multiplication avalanche photodiode (LSAMBM APD) with rectangular layout based on SOI film had been investigated as a promising candidate in the high-speed weak-light detection application. In this article, the layout-dependent characteristics of LSAMBM APD were investigated furthermore. Comparing to rectangular layout, the circular layout could shorten the length and improve electric field intensity of absorption region under the same sensitive area. In this way, carriers’ drift velocity could be accelerated, and the photon-generated carriers would be more effectively separated to achieve high responsivity and fast frequency response in LSAMBM APD with circular layout. When the illumination wavelength was 400 nm and input optical power was 0.001 W/cm2, the circular layout could enhance LSAMBM APD to achieve high responsivity and fast frequency response under the reverse bias voltage of 8.11 V and 9.2 V, and reach to 1236.9A/W and 3.2GHz, respectively. All results revealed that the LSAMBM APD with circular layout was more appropriate to high-speed single photon detection systems.

Molecular symmetry is a decisive factor for the two-photon absorption (2PA) properties of an organic chromophore. In order to explore its impact on the 2PA cross section of squaraine dyes, we synth...

The input–output power response of the glycerol solution with different glycerin concentrations is studied. It is found that there is an optical power limiting activity for glycerol. The transmission of the optical power is found to decrease with increasing the concentration. The decrease in optical power follows the well-known Beer–Lambert law at lower powers. However, at higher powers we observe an optical limiting property with saturated output powers. The saturated output power of the solution for various concentrations is estimated and is found to decrease with an increase in the concentration of the solution. The limiting mechanism is found to be reverse-saturable absorption and is discussed on the basis of the five level energy diagram of the molecular system.

Fiber Bragg gratings (FBG) are ideal sensors for temperature, strain or vibration sensing applications with their advantages over conventional electronics sensor systems. In this paper, two different FBG sensor interrogation schemes based on broadband ASE source and tunable EDFRL source are demonstrated and compared. With both interrogator configurations, the response of the FBG sensor to temperature change is found to be linear and the sensitivities are measured as 11 pm/°C and 10.5 pm/°C, respectively. The experimental results have revealed that the optical power reflected from the FBG sensor is almost 20 dB higher with tunable EDFRL source than broadband ASE source. Thus, an interrogation method with tunable EDFRL can be suitable for remote, quasi-distributed sensor applications requiring high output power and OSNR.

All-CMOS monolithic microdisplay technologies have been attracting attention due to their direct integration of light-emitting pixel arrays and driving circuits on a single silicon substrate. Improvements to optical power efficiency have been a hot spot for all-silicon microdisplay technologies. MOS-like gate-control structure avalanche-mode light-emitting diodes (AMLEDs) that employ hot-carrier electroluminescence to produce light emission are used to enhance the optical power efficiency of pixel units. A semi-active matrix mode is used to reduce the power consumption of driver circuits. A $100\times 100$ pixel array with an all-CMOS monolithic microdisplay system is demonstrated using standard $0.18\mu \text{m}$ CMOS technology. The optical emission power and the breakdown voltage of the proposed AMLEDs are increased by 139.2% and reduced by more than 67%, respectively. The optical-power efficiency is $5.98\times 10 ^{{-7}}$ which is comparable to the best reported so far in all-CMOS monolithic microdisplay chip. With its significant optical-power efficiency, the proposed microdisplay technology has broad application prospects in near-to-eye display and head mounted displays (HMDs).

A dual Fabry-Perot (FP) interferometric fiber-optic acoustic sensor based on sandwich-structure composite diaphragm is proposed, where fixed phase difference is generated by two FP interferometers (FPIs) with different cavity length. An ellipse fitting differential cross multiplication (EF-DCM) interrogation process is applied for phase demodulation to overcome drawbacks of quadrature point based intensity demodulation, such as temperature drifting, optical power jitter and limited dynamic range. Besides, benefiting from the large area sandwich-structure composite diaphragm, high sensitivity and wide flat frequency response are obtained. Experimental results show that phase sensitivity is -121.11 dB re 1 rad/μPa@250 Hz and sensitivity fluctuation is below 0.8 dB between 2-250Hz. To prove the high stability of the demodulation system, acoustic signal test is performed at different wavelength and different optical power and a fluctuation below 3% is observed. Moreover, profiting from the dual FP sensor structure, the acoustic sensor is get rid of influence of temperature drifting which usually leads to variation of cavity length of fiber optic acoustic sensor. The proposed sensor structure also overcomes drawbacks of traditional dual wavelength demodulation such as extra noise introduced by erbium doped fiber amplifier (EDFA) and high cost.

Simultaneous over 40-W electric power and optical data transmission using an optical fiber is demonstrated for optically powered remote antenna units in future mobile communication networks. In this article, to further increase the delivered electric power by power-over-fiber link using a double-clad fiber, we improve the link design to extract a higher feed light power from the double-clad fiber output. Furthermore, to increase the electric power for driving remote antenna units, we employ a specially customized photovoltaic power converter that directly converts optical power into electric power. The photovoltaic power converter can input a feed light with power of over 20 W and has a high optical-to-electrical conversion efficiency of over 50%. As a result, the combination of the improved power-over-fiber link design and the use of the photovoltaic power converter successfully achieves the electric power delivery of up to 43.7 W. This is the highest electric power delivery demonstration by power-over-fiber with optical data signals using a single optical fiber, to the best of the authors’ knowledge.

Silicon photonic optical phased arrays are promising solutions for solid-state LIDAR. But the nonlinear absorption significantly saturates the optical power in the waveguides at 1.5-μm wavelengths. Besides, the high refractive index contrast of silicon grating exhibits a strong diffraction strength of the antenna, which results in a limited aperture of the device. These ultimately place a limit on the detection accuracy and reach. Here, a shallow etched two-dimensional subwavelength grating structure is proposed to improve the efficiency and aperture of the waveguide antenna. A reduction of diffraction strength is achieved via nanohole structure instead of conventional grating lines. Thus, a millimeter-long optical antenna is demonstrated with a peak efficiency of 71%. The far-field diffracted beam width of 0.035° and vertical field-of-view of 17.5° are achieved within 100 nm wavelengths range from 1.95 μm to 2.05 μm. The operation at 2-μm waveband also guarantees better eye-safety and significantly reduces the nonlinear absorption in silicon waveguide compared with conventional 1.5-μm band.

This article presents a new directional coupling between two transverse strip metal-insulator-metal (TS-MIM) waveguides on silicon-on-insulator (SOI) platform at 1.55 μm wavelength. The directional coupling between two TS-MIM waveguides shows a coupling length of less than 2 μm for a ridge width and gap width of 150 nm and 50 nm, respectively. Meanwhile, a direct coupling between a hybrid plasmonic (HP) waveguide and a TS-MIM waveguide was also investigated. The maximum optical power transmission from the HP-waveguide to the TS-MIM waveguide will occur at 1.3 μm long TS-MIM waveguide. An HP-waveguide coupled to the TS-MIM waveguide with a tapered tip is incredibly beneficial in nanofocusing applications.

A polymer based horizontal single step waveguide for the sensing of alcohol is developed and analyzed. The waveguide is fabricated by 3-dimensional (3D) printing digital light processing (DLP) technology using monocure 3D rapid ultraviolet (UV) clear resin with a refractive index of n = 1.50. The fabricated waveguide is a one-piece tower shaped ridge structure. It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region. With the surface roughness generated from the 3D printing DLP technology, various waveguides with different gap sizes are printed. Comparison is done for the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect. This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide, thus changing the waveguide from the leaky type (without alcohol) to the guided type (with alcohol). Using this principle, the analysis of alcohol concentration performing as a larger increase in the transmitted light intensity can be measured. In this work, the sensitivity of the system is also compared and analyzed for different waveguide gap sizes with different concentrations of isopropanol alcohol (IPA). A waveguide gap size of 300 µm gives the highest increase in the transmitted optical power of 65% when tested with 10 µL (500 ppm) concentration of IPA. Compared with all other gaps, it also displays faster response time (t = 5 seconds) for the optical power to change right after depositing IPA in the chamber. The measured limit of detection (LOD) achieved for 300 µm is 0.366 µL. In addition, the fabricated waveguide gap of 300 µm successfully demonstrates the sensing limit of IPA concentration below 400 ppm which is considered as an exposure limit by “National Institute for Occupational Safety and Health”. All the mechanical mount and the alignments are done by 3D printing fused deposition method (FDM).

We report the phase shift of two types of photodetectors for a variation of bias voltage and optical power. One type is PIN-PD and the other is a modified uni-traveling carrier photodetector (MUTC-PD). In PIN-PD, the phase change shows a photocurrent-dependent variation of about 15 degrees at 3 GHz. It exhibits good stability over a wide bandwidth as the bias voltage changes. By comparison, the phase shift of the MUTC-PD is more sensitive to the bias voltage and the photocurrent. The continuous tunable range of phase shift in MUTC-PD reaches 50 degrees at 10 GHz. It is demonstrated that the adjustable phase shift mainly results from the transit time and the impedance dynamic effects in response to the optical power and bias voltage.

High-power semiconductor lasers based on AlGaInAs/InP heterostructures and emitting in the spectral range 1.9 – 2.0 μm are developed. Strain compensation in the active region makes it possible to use InGaAs quantum wells with a compressive strain of about 2.0% – 2.5%. The operation of a laser with an ultra-narrow waveguide at wavelengths increasing from 1.4 – 1.6 to 2.0 μm is studied. At room temperature, the semiconductor lasers with a stripe contact width of 100 μm demonstrates a cw output optical power of 1.0 W with a wavelength of 1.91 μm at a pump current of 6.5 A and with a wavelength of 1.98 μm at a pump current of 7.2 A.

The state-of-the-art optical coherence technology (OCT) has its limitation, such as bulky and quite expensive. Miniaturization and integration of the OCT system are promising to get a compact, less costly, and more stable device. In this paper, we report the influence of optical power splitting on the sensitivity and axial resolution in spectral-domain OCT (SD-OCT) on silicon chip using tandem Mach-Zehnder directional coupler (MZDC) based broadband coupler through particle swarm optimization (PSO). A less-flat wavelength response from a broadband coupler in an interferometer for SD-OCT on-chip will decrease the sensing sensitivity. The arrayed waveguide grating (AWG) as a spectrometer in SD-OCT typically suffers from the axial resolution degradation due to the non-flat free spectrum range (FSR). To avoid the higher optical loss from the large FSR, the PSO manipulation in MZDC is then proposed to demonstrate U-shaped wavelength compensation on the non-flat AWG spectrum. With the broadband coupler configuration , a SD-OCT on-chip can maintain the sensitivity and axial resolution performance.

The refraction characteristics of 50 nm thickness of PbTiO3 (PTO) film pumped by various optical power in terahertz (THz) range is measured by THz time domain spectrum. Experiments indicated that t...

Poly (3 - Hexylthiophene - Co - Thiophene) copolymer was prepared by using the addition polymerization method. The Nonlinear optical properties and the behavior of the optical power limiting of the prepared polymer blend poly (3HT- Co - Th) - PMMA films were studied by using the z - scan technique for different weight ratios of the copolymer poly (3HT- Co - Th). In the present work, a continuous wave (CW) diode - pumped solid - state laser (DPSSL) of wavelengths 532 nm was used for the irradiation of the prepared film samples. The nonlinear optical parameters such as, the nonlinear refractive index (n2), the nonlinear absorption coefficient (β), and the third - order - nonlinear optical susceptibility (χ (3)) of the polymer blend poly (3HT- Co - Th) - PMMA films were determined for different weight ratios of the copolymer poly (3HT- Co - Th). It is observed that the polymer blend poly (3HT - Co - Th) - PMMA films exhibit saturable absorption (SA) and self - defocusing effects, and this gives an indication that both, the nonlinear refractive index (n2) and the nonlinear absorption coefficient (β), have negative values. The obtained results indicate that the prepared polymer blend poly (3HT - Co - Th) - PMMA films are promising materials and can be considered as suitable materials for different optical and electronic applications.

Thyristors operated at switching point are highly sensitive to external physical signals such as light or temperature. However, due to the instability of sensitive switching point, conventional thyristors are commonly used as optical switches and hardly applied for low-light level detection. In this work, a silicon-based gate-controlled lateral thyristor (GC-LT), which takes advantage of high sensitivity at low-light, is studied by numerical simulation. A thyristor photodetector circuit and a novel super-off Reset operation method are also proposed to bias the GC-LT over the switching point quickly and allow the photodetector to be operated in a monotonic dynamic multi-sampling mode to achieve high sensitivity to low-light. Simulation results show that the Reset time can be shortened to $ < 10~\mu \text{s}$ without trigging the GC-LT. The trigger time of the photodetector is sensitive to the optical power density ranging from $1\times 10^{-9}$ to $2.5\times 10^{-6}$ W/cm2. Furthermore, the average optical gain is about 8.0-6.3, approximately one order of magnitude higher than that of the Si pinned photodiode.

In this article, we proposed a simple optical sensor for flow measurement. The sensor structure is based on an in-line Mach–Zehnder interferometer formed by splicing an input single-mode fiber section and an output single-mode fiber section to a single-mode fiber sandwiched by two multimode fibers; it is called SMSMS sensor. The proposed sensor presents a high sensitivity due to low order modes that propagate in the middle single-mode fiber (SMF) cladding. The sensor is experimentally investigated and validated in which the results show good agreement between the optical power and flow for monitoring single- and two-phase flows using water and air fluids. Using this sensor, it is possible to identify the presence of air in the pipeline, in addition to the identification of the flow pattern. Thus, the proposed sensor is an interesting alternative for measuring single- and two-phase flows.

On-chip optical switches have emerged as a new class of photonic components for high-performance optical communication networks and on-chip interconnects, in which the all-optical configuration without the incorporation of other control-means is highly desired. While two-dimensional (2D) ultrathin materials demonstrate their great potential in developing ultrafast all-optical switches owing to their unique light–matter interaction, such investigations have so far been limited to the fiber optic platform or free space. Here, we realize an all-optical on-chip switch from a silicon waveguide-based asymmetric Mach–Zehnder interferometer (MZI) structure enabled by 2D ultrathin Ga2S3. Upon the visible light excitation at 532 nm, excessive photocarriers in Ga2S3 cause a change of the refractive index and subsequently a phase variation between MZI arms at the 1550 nm operation wavelength, triggering on the optical switch. On the other hand, the switch is off without the visible light stimulation, as the phase variation is recovered due to the ultrafast photo-exciton relaxation behavior of Ga2S3. The Ga2S3-enabled all-optical switch is driven at an extremely small optical power density of 0.12 W cm−2 and exhibits a response and recovery time of 26.3 and 43.5 μs, respectively, which as a combination is superior to those of fiber optic-based all-optical switches enabled by 2D materials. This work may provide a viable approach to develop on-chip all-optical photonic components for practical integrated photonic chips.

The external cavity laser (ECL), which is mainly used for coherent light communication, is characterized by narrow line width and low power consumption. In practical application, the output optical power of ECL will decrease when the ambient temperature is the high or low temperature. Through the use of finite element commercial software Ansys, it was found that the mechanical structure had the slight deflection change at high or low temperatures. Compared with the room temperature, the maximum deflection angle at high or low temperatures was 0.04°. The cavity length of ECL was long, combined with the optical path simulation software Zemax, the slight deflection change would cause the big change of optical path, affect the coupling efficiency and then lead to the reduction of output optical power. The change of optical path was confirmed by the experimental measurement, and based on the theory of power reduction caused by the deflection change, the methods of shortening the cavity length and thickening the base were proposed to reduce the variation of output optical power with the ambient temperature from the point of design. The proposed model and ideas can provide quantitative analysis ideas for the correlation analysis of power and temperature of similar products.

The hole injection efficiency is one of the bottlenecks that restrict the external quantum efficiency (EQE) and optical power of AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). The polarization-induced positive sheet charges at the last quantum barrier (LQB)/electron blocking layer (EBL) interface reflect the holes back to the p-type layer and weaken the hole injection capability into the active region. In this work, we designed and incorporated a polarization-engineered AlxGa1-xN/AlyGa1-yN superlattice layer at the LQB/EBL interface. The positive sheet charges at the LQB/EBL interface can be inverted into negative charges with optimal Al compositions in the AlxGa1-xN/AlyGa1-yN superlattice layer. The electron confinement and hole injection efficiency can also be improved through increasing the effective barrier height for electrons and decreasing the effective barrier height for holes, resulting in an enhanced optical power by 29.4% and alleviated efficiency droop by 78.4% for the proposed device with an Al0.67Ga0.33N/Al0.7Ga0.3N superlattice insertion layer. The sheet charge engineering method by polarization provides an alternative approach to boost the hole injection efficiency towards an enhanced device performance for DUV LEDs.

We describe a novel chaotic macropulse green laser designed employing the pulse modulation of a 520 nm laser diode with optical feedback. We analyze the characteristics of these chaotic macropulses, in view of effects of the feedback intensity, injection current, modulation voltage, duty cycle, and modulation frequency on the pulses, including their full width at half maximum (FWHM) values and peak side-lobe levels (PSLs). We determine an optimum feedback intensity of 11.7% based on the maximum peak optical power and the scope of the amplitude jitter of the chaotic macropulse. The optimum injection currents are approximately between 60 and 70 mA, and the modulation voltages between 2.0 and 3.0 V are limited by the radio-frequency (RF) power. We found that chaos also occurred at the bottom of the macropulse when the duty cycle was less than approximately 30%. The modulation frequencies were loaded from 4 to 20 MHz; this range was restricted by the performance of the RF input port on the laser diode mount. The range resolution of the chaotic macropulses is approximately 3 cm in seawater; it is achieved with lower power consumption than a continuous wave chaotic laser.

A novel tetraphenylethylene (TPE) architecture that makes use of a disilane bridge was developed to successfully prepare organic optical power limiting (OPL) materials with high transparency. The σ-bridged TPE derivatives exhibit enhanced solid-state emission efficacies up to 4 times that of TPE. Due to the unique σ-electron delocalization, the incorporated Si–Si bridge gives rise to intense nonlinear optics (NLO) properties. These compounds show favorable optical transparency in the visible region, since the σ–π interaction has a relatively minor effect on the absorption properties of TPE. The poly(bisphenol A carbonate) (PBC) thin films of disilane-bridged compounds exhibit significant reverse saturable absorbance (RSA) responses during Z-scan measurements at 532 nm. In contrast, negligible OPL properties were observed in tetrahydrofuran (THF) solution and when a PBC thin film was prepared with TPE. The disilane-bridged molecular system represents a novel and easily prepared architecture for the construction of solid-state optical limiting materials.

Проблематика. Після імплантації монофокальних інтраокулярних лінз (ІОЛ) ризик розвитку світлових явищ становить 9 %, після імплантації мультифокальних ІОЛ – 41 %. Ці ефекти не тільки створюють дискомфорт, а й погіршують якість отриманого зображення. Існуючі ІОЛ мають низку недоліків, які викликають різного типу фотичні феномени.Мета. Оптичний розрахунок і моделювання параметрів, які повинна мати ІОЛ, задля зменшення фотичних феноменів і фонового засвічення сітківки з підвищенням контрастності передачі. Створення на основі отриманих результатів ІОЛ нової конструкції.Методика реалізації. Для розрахунку відбитих променів використано закон Снеліуса–Декарта, згідно з яким отримано значення критичного кута для гідрофобної акрилової ІОЛ із показником заломлення 1,55 за довжини хвилі λ = 0,55 мкм, що межує з водянистою вологою, показник заломлення якої 1,33. Розрахунок втрат переданого світла визначався на основі коефіцієнта френелівського відбиття. Взято оптичну систему, в якій апертурна діафрагма відігравала роль зіниці. За допомогою програмного середовища Zemax 13 змодельовано хід променів для ока людини, сагітальна вісь якого становить28 мм, за різної глибини розміщення ІОЛ. Отримані результати застосовано для розробки нової ІОЛ в середовищі SolidWorks.Результати. Проведені розрахунки дали змогу виявити недоліки сучасних ІОЛ і методи їх усунення. Встановлено, що для зменшення ризику появи фотичних феноменів і, як наслідок, підвищення світлопередачі ІОЛ повинна розміщуватись на відстані від райдужної оболонки не менше ніж 4 мм, мати в собі два і більше оптичних шари, показник заломлення яких змінюється в напрямку до центра лінзи, та шорсткість поверхні 35 нм. На основі розрахунків здійснено моделювання в середовищі Zemax 13, що підтвердило їх достовірність. При моделюванні з цими параметрами середнє квадратичне відхилення зображення повністю потрапило в межі диска Ейрі, що має розмір 3,598 мкм за величини зображення 2,972 мкм. Таким чином, оптична система вважається дифракційно обмеженою, і подальші оптичні оптимізації неможливі. Із застосуванням програмного пакета Solidworks й отриманих результатів запропоновано власну модель ІОЛ під назвою “NVision OP”, розміри якої відповідають розмірам нативного кришталика. ІОЛ має товщину оптичної частини 1 мм з діаметром 5 мм. У цілому пустотіла, об’ємозамінна ІОЛ з оболонкою має діаметр 10 мм і товщину 5 мм, товщина оболонки становить 150 мкм.Висновки. Дослідження виявило низку чинників, які потребують удосконалення та усунення для попередження виникнення фотичних ефектів різного типу. До них відносяться: шорсткість поверхні лінзи, величина заломлюючої сили ІОЛ, форма, товщина краю лінзи, глибина імплантації ІОЛ в оці, факодонез та зміщення лінзи, діаметр апертурної діафрагми. Після оптимізації даних, згідно з розрахунковими результатами, проведено моделювання в середовищах Zemax 13 та Solidworks. На основі цього запропоновано модель ІОЛ NVision OP; фотичні ефекти, а саме, arcs, flare, flashes, glare і halo, максимально усунені. Пустотіла, об’ємозамінна ІОЛ NVision OP має на оболонці елементи, що уможливлюють шовну фіксацію, яка попереджує її дислокацію. Для імплантації запропонованої ІОЛ NVision OP рекомендується використовувати віскоеластик та інжектор фірми Alcon із картриджем В. Завдяки формі ІОЛ, яка відповідає нативному кришталику людини, лінза розміщується на місці факоемульсифікованої речовини, а сама імплантація не займає багато часу., Background. After implantation of monofocal intraocular lenses (IOLs), the risk of developing light phenomena is 9%, and after implantation of multifocal IOLs the one is 41%. These effects not only cause discomfort, but also poor image quality. The existing IOLs have a number of deficiencies that cause different types of photic phenomena.Objective. The aim of the work is optical calculation and simulation of the parameters that an IOL should have in order to reduce photic phenomena and retinal background illumination while increasing the transmission contrast. We also are aimed to design a new IOL on the basis of the results obtained.Methods. To calculate the reflected rays, we used the Snell–Descartes law, according to which we obtained the value of the critical angle for a hydrophobic acrylic IOL with the refractive index of 1.55 at the wavelength of λ = 0.55 μm. This is consistent with aqueous humor, the refractive index of which is 1.33. The calculation of the transmitted light loss was determined by Fresnel reflection coefficient. We handled with optical system in which the aperture diaphragm fulfilled the role of a pupil. Using the Zemax 13 software environment, we simulated ray path for a human eye, the sagittal axis of which is 28 mm at different height of IOL placement. We applied the results obtained to design a new IOL in the SolidWorks environment.Results. The calculations made it possible to identify the shortcomings of modern IOLs and methods for their elimination. It was found that in order to reduce the risk of photic phenomena and, as a result, of increasing luminous transmission, an IOL should be placed at a distance of at least 4 mm from the iris. It should contain two or more optical layers, the refractive index of which changes towards the center of the lens, and have the surface roughness of 35 nm. Based on the calculations, we carried out simulation in the Zemax 13 environment, which confirmed their veracity. When simulated with these parameters, the standard deviation of an image fell completely within the Airy disk, which has a size of 3.598 μm with an image size of 2.972 μm. Thus, the optical system is considered diffraction limited and no further optical optimizations are possible. Using the Solidworks software and the results obtained, we proposed the proprietary IOL model called "NVision OP". This IOL has an optical part thickness of 1 mm with a diameter of 5 mm. In general, the hollow, volume-replacing IOL with a coating has a diameter of 10 mm and a thickness of 5 mm, the thickness of the coating is 150 μm.Conclusions. The study revealed a number of factors that require improvement and elimination to prevent the occurrence of various types of photic effects. These include: lens surface roughness, IOL refractive power, shape, lens edge thickness, depth of IOL implantation into an eye, phacodonesis and lens displacement, aperture diaphragm diameter. After data optimization, according to the calculated results, we carried out the simulation in the Zemax 13 and Solidworks environments. On the basis of this simulation we proposed the model of an intraocular lens "NVision OP"; the photic effects namely arcs, flare, flashes, glare and halo are eliminated as much as possible. The hollow, volume-replacing IOL "NVision OP" has elements on its coat that allow to use the suture fixation, which prevents the dislocation of the IOL. For the implantation of the proposed IOL "NVision OP", it is recommended to use a viscoelastic and the Alcon injector with the cartridge B. Due to the fact that the shape of the IOL corresponds to the native human lens, the lens is located in the place of the phacoemulsified substance, and the implantation does not take much time., Проблематика. После имплантации монофокальных интраокулярных линз (ИОЛ) риск развития световых явлений составляет 9 %, после имплантации мультифокальных ИОЛ – 41 %. Эти эффекты не только создают дискомфорт, но и ухудшают качество получаемого изображения. Существующие ИОЛ имеют ряд недостатков, которые вызывают разного типа фотические феномены.Цель. Оптический расчет и моделирование параметров, которыми должна обладать ИОЛ, для уменьшения фотических феноменов и фоновой засветки сетчатки с повышением контрастности передачи. Создание на основе полученных результатов ИОЛ новой конструкции.Методика реализации. Для расчета отраженных лучей применен закон Снеллиуса–Декарта, согласно которому получено значение критического угла для гидрофобной акриловой ИОЛ с показателем преломления 1,55 при длине волны λ = 0,55 мкм, что граничит с водянистой влагой, показатель преломления которой составляет 1,33. Расчет потерь передаваемого света определялся на основе коэффициента френелевского отражения. Принята оптическая система, в которой апертурная диафрагма играла роль зрачка. С помощью программной среды Zemax 13 смоделирован ход лучей для глаза человека, сагиттальная ось которого составляет 28 мм, при разной глубине размещения ИОЛ. Полученные результаты применены для разработки новой ИОЛ в среде SolidWorks.Результаты. Проведенные расчеты позволили выявить недостатки современных ИОЛ и методы их устранения. Установлено, что для уменьшения риска появления фотических феноменов и, как следствие, повышения светопередачи ИОЛ должна размещаться на расстоянии от радужной оболочки не менее 4 мм, иметь в себе два и более оптических слоя, показатель преломления которых изменяется в направлении к центру линзы, и шероховатость поверхности 35 нм. На основе расчетов осуществлено моделирование в среде Zemax 13, что подтвердило их достовреность. При моделировании с этими параметрами среднее квадратическое отклонение изображения полностью попало в пределы диска Эйри, имеющего размер 3,598 мкм при величине изображения 2,972 мкм. Таким образом, оптическая система считается дифракционно ограниченной, и дальнейшие оптические оптимизации невозможны. С применением программного пакета Solidworks и полученных результатов предложена собственная модель ИОЛ под названием “NVision OP”, которая имеет толщину оптической части 1 мм с диаметром 5 мм. В целом полая, объемозамещающая ИОЛ с оболочкой имеет диаметр 10 мм и толщину 5 мм, толщина оболочки составляет 150 мкм.Выводы. Исследование выявило ряд факторов, которые требуют совершенствования и устранения для предупреждения возникновения фотических эффектов различного типа. К ним относятся: шероховатость поверхности линзы, величина преломляющей силы ИОЛ, форма, толщина края линзы, глубина имплантации ИОЛ в глазу, факодонез и смещение линзы, диаметр апертурной диафрагмы. После оптимизации данных, согласно расчетных результатов, проведено моделирование в средах Zemax 13 и Solidworks. На основе этого предложена модель ИОЛ “NVision OP”; фотические эффекты, а именно arcs, flare, flashes, glare и halo, максимально устранены. Полая, объемозамещающая ИОЛ "NVision OP" имеет на оболочке элементы, позволяющие использовать шовную фиксацию, которая предупреждает ее дислокацию. Для имплантации предложенной ИОЛ “NVision OP” рекомендуется использовать вискоэластик и инжектор фирмы Alcon с картриджем В. Благодаря форме ИОЛ, которая соответствует нативному хрусталику человека, линза располагается на место факоэмульсифицированого вещества, при этом имплантация не занимает много времени.

An investigation has been performed of 1.55-μm vertical-cavity surface-emitting lasers based on heterostructures with a buried tunnel junction (BTJ) with a height difference of 15 nm. The devices are obtained by wafer fusion of heterostructures grown by molecular beam epitaxy and provide single-mode lasing at a BTJ diameter of up to 8 μm. A decrease in the BTJ size leads to a sharp increase in the threshold current, the output optical power, and the resonance frequency at the lasing threshold. Stable single-mode lasing takes place due to the smoothed boundary of the buried surface relief, which induces a gradual change in the profile of the effective refractive index in the lateral direction with the effective current confinement retained. This makes it possible to reduce significantly the transverse optical confinement factor for the higher-order modes even at a large BTJ size. However, at a small BTJ size, it leads to the formation of a saturable absorber in unpumped parts of the active region.

We demonstrate a high-power on-chip 1550-nm laser implemented by passive flip-chip integration of a curved-channel, double-pass InGaAsP/InP slab-coupled optical waveguide amplifier (SCOWA) onto a photonic integrated circuit (PIC) containing a silicon nitride (SiN) waveguide and distributed Bragg reflector (DBR) grating. The combined chip-scale SCOW external cavity laser (SCOWECL) has single mode emission with 312 mW of optical power at a drive current of 2.5 A, and exhibits a side mode suppression ratio (SMSR) of 55 dB, peak photon conversion efficiency (PCE) of 10%, low relative-intensity noise (RIN) of ~160 dB/Hz, and an integrated linewidth of 192 kHz. Additionally, we demonstrate a multi-wavelength SCOWECL array comprised of four SCOWAs coupled to SiN-waveguide DBR gratings. The four-element array generates 80 mW per channel when the SCOWAs are driven in parallel (1.25 A/channel) with ~1-nm wavelength spacing centered at 1533 nm. We describe the fabrication and hybrid integration processes. The measured SCOWA-to-waveguide coupling loss is estimated to be 1.6 +/-1.0 dB which agrees well with the simulation.

We present the implementation of an efficient terahertz (THz) photoconductive antenna (PCA) emitter design that utilizes high mobility carriers in the two-dimensional electron gas (2DEG) of a modulation-doped heterostructure (MDH). The PCA design is fabricated with recessed metal electrodes in direct contact with the 2DEG region of the MDH. We compare the performance of the MDH PCA having recessed contacts with a PCA fabricated on bulk semi-insulating GaAs, on low temperature-grown GaAs, and a MDH PCA with the contacts fabricated on the surface. By recessing the contacts, the applied bias can effectively accelerate the high-mobility carriers within the 2DEG, which increases the THz power emission by at least an order of magnitude compared to those with conventional structures. The dynamic range (62 dB) and bandwidth characteristics (3.2 THz) in the power spectrum are shown to be comparable with the reference samples. Drude-Lorentz simulations corroborate the results that the higher-mobility carriers in the MDH, increase the THz emission. The saturation characteristics were also measured via optical fluence dependence, revealing a lower saturation value compared to the reference samples. The high THz conversion efficiency of the MDH-PCA with recessed contacts at low optical power makes it an attractive candidate for THz-time domain spectroscopy systems powered by low power fiber lasers.