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Plasmonic nanostructures (PNs) have transformed nanophotonics by offering control over electromagnetic waves. Although innovative structural designs have demonstrated PNs' potential, significant fabrication challenges, including the precise alignment of heterogeneous materials, remain. Using chloroform and pre‐UV exposure (PUVE) to enhance adhesion at the metal‐dielectric interface (MDI) addresses these challenges. PUVE preserves plasmon resonance in the MDI, ensuring high performance without compromising structural integrity. Through an annealing process, PUVE strengthens van der Waals bonds, ensuring chloroform molecules remain on the Ag surface during chloroform residue removal, allowing: i) stable preservation of the Ag thin film on the PNs during stripping; and ii) the formation of chloroform‐mediated heterogeneous bonding (CMHB) using energy supplied by UV‐nanoimprint lithography (UV‐NIL). This approach enables PNs' scalable fabrication with enhanced adhesion properties, while CMHB increases adhesion between the UV‐curable resin and Ag, offering scalability to large‐area applications with UV‐NIL. The structural morphology and chemical properties of the fabricated PNs are analyzed using scanning electron microscopy, atomic force microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy. These PNs demonstrate potential in CCD filters, enhancing optical signal amplification for real‐time imaging at the 785 nm band. This robust fabrication method advances PNs' performance and scalability, advancing nanophotonics and related applications. [ABSTRACT FROM AUTHOR]

AIM:To evaluate the effect of optical amplification on macular retinal thickness measurements in myopic eyes of children and adolescents using optical coherence tomography(OCT).METHODS:A total of 68 cases(126 eyes)of children and adolescents aged 6 to 18 years old attending our optometric center from April 2023 to January 2024 were selected. They were divided into 44 cases(83 eyes)in the mild myopia group(-0.50 D0.05). In the moderate myopia group, the differences between the retinal thickness in each quadrant of the macula and the mean retinal thickness before and after correction were statistically significant(all P0.05). There were significant differences between the two groups in the macular fovea, the nasal side of the inner ring, the temporal side of the inner ring, the upper inner ring, the lower inner ring, the nasal side of the outer ring, and the mean retinal thickness after correction(all P

9,9‐bis (diphenylphosphorylphenyl) fluorene (FDPO) and dibenzotetrathienoacene (DBTTA), are synthesized as the neutral and anionic ligands, respectively, to prepare the ErIII coordination polymer [Er(DBTTA)3(FDPO)]n. Based on the intramolecular energy transfer, optical gains at 1.5 µm are demonstrated in [Er(DBTTA)3(FDPO)]n‐doped polymer waveguides under excitations of low‐power light‐emitting diodes (LEDs) instead of laser pumping. A ligand‐sensitization scheme between organic ligands and Er3+ ions under an excitation of an ultraviolet (UV) LED is established. Relative gains of 10.5 and 8.5 dB cm−1 are achieved at 1.53 and 1.55 µm, respectively, on a 1‐cm‐long SU‐8 channel waveguide with a cross‐section of 2 × 3 µm2 and a 1.5‐µm‐thick [Er(DBTTA)3(FDPO)]n‐doped polymethylmethacrylate (PMMA) as upper cladding. The ErIII coordination polymer [Er(DBTTA)3(FDPO)]n can be conveniently integrated with various low‐loss inorganic waveguides to compensate for optical losses in the C‐band window. Moreover, by relying on the intramolecular energy transfer and UV LED top‐pumping technology, it is easy to achieve coupling packaging of erbium‐doped waveguide amplifiers (EDWAs) with pump sources in planar photonic integrated chips, effectively reducing the commercial costs. [ABSTRACT FROM AUTHOR]

Abstract 9,9‐bis (diphenylphosphorylphenyl) fluorene (FDPO) and dibenzotetrathienoacene (DBTTA), are synthesized as the neutral and anionic ligands, respectively, to prepare the ErIII coordination polymer [Er(DBTTA)3(FDPO)]n. Based on the intramolecular energy transfer, optical gains at 1.5 µm are demonstrated in [Er(DBTTA)3(FDPO)]n‐doped polymer waveguides under excitations of low‐power light‐emitting diodes (LEDs) instead of laser pumping. A ligand‐sensitization scheme between organic ligands and Er3+ ions under an excitation of an ultraviolet (UV) LED is established. Relative gains of 10.5 and 8.5 dB cm−1 are achieved at 1.53 and 1.55 µm, respectively, on a 1‐cm‐long SU‐8 channel waveguide with a cross‐section of 2 × 3 µm2 and a 1.5‐µm‐thick [Er(DBTTA)3(FDPO)]n‐doped polymethylmethacrylate (PMMA) as upper cladding. The ErIII coordination polymer [Er(DBTTA)3(FDPO)]n can be conveniently integrated with various low‐loss inorganic waveguides to compensate for optical losses in the C‐band window. Moreover, by relying on the intramolecular energy transfer and UV LED top‐pumping technology, it is easy to achieve coupling packaging of erbium‐doped waveguide amplifiers (EDWAs) with pump sources in planar photonic integrated chips, effectively reducing the commercial costs.

Bismuth(Bi)‐doped photonic materials with broadband near‐infrared luminescence can be used in applications such as high‐capacity fiber communication, fiber laser, and biological imaging. The scalable fabrication of Bi‐doped fibers with high dopant solubility, high optical activity, and broadband optical response still remains a significant challenge. In this study, the comprehensive studies on the physical, chemical, mechanical, and optical responses of a Bi‐doped glass system are performed and a Bi‐doped germanate multicomponent glass system is proposed to be the promising candidate. The deactivation mechanism of Bi in a glass matrix is investigated and prevented by controlling the fiber drawing. In addition, a Bi‐doped multicomponent germanate glass fiber with a high level of Bi doping is successfully constructed. Finally, a principle compact fiber amplifier device is fabricated for broadband optical amplification. This device can be potentially used for increasing the capacity of telecommunication systems. [ABSTRACT FROM AUTHOR]

Optical switching is an essential part of photonic integrated circuits and the focus of research at the moment. In this research, an optical switch design working on the phenomenon of guided-mode resonances in a 3D photonic-crystal-based structure is reported. The optical-switching mechanism is studied in a dielectric slab-waveguide-based structure operating in the near-infrared range in a telecom window of 1.55 µm. The mechanism is investigated via the interference of two signals, i.e., the data signal and the control signal. The data signal is coupled into the optical structure and filtered utilizing guided-mode resonance, whereas the control signal is index-guided in the optical structure. The amplification or de-amplification of the data signal is controlled by tuning the spectral properties of the optical sources and structural parameters of the device. The parameters are optimized first using a single-cell model with periodic boundary conditions and later in a finite 3D-FDTD model of the device. The numerical design is computed in an open-source Finite Difference Time Domain simulation platform. Optical amplification in the range of 13.75% is achieved in the data signal with a decrease in the linewidth up to 0.0079 µm, achieving a quality factor of 114.58. The proposed device presents great potential in the field of photonic integrated circuits, biomedical technology, and programmable photonics. [ABSTRACT FROM AUTHOR]

Nanoscale conductive materials are often used for inducing localized free electron oscillations known as plasmons . This is due to their high electronic excitability under optical irradiation owing to their super-small volume. Recently, plasmons have been of interest for enhancing the gain-bandwidth product of optical amplifiers. There are currently two well-established mechanisms for light amplification. The first one is via stimulated emission of radiation (lasers) using a given energy source and often an optical feedback mechanism. The second one is based on the nonlinear coupling of a low-intensity input wave and a high-intensity pump wave for energy exchange (parametric amplifiers). Both techniques have shortcomings. Lasers have a small operation bandwidth and offer a limited gain, but require moderate energy pumping to operate. Whereas optical parametric amplifiers (OPAs) offer a high operation bandwidth along with a much higher optical gain, with the drawback of requiring intense pumping to be functional. The aim of this paper is to introduce a technique that combines the advantages and eliminates the drawbacks of both techniques in the nanoscale to allow for a better amplification performance in integrated optical devices. This is achieved by inducing a plasmonic chirp in conductive nanomaterials a.k.a nano-antennas, which enables the confinement of an enormous electric energy density that can be coupled to an input beam for amplification. Using the Finite Difference Time Domain numerical-method with the material parameters of well-known semiconductors, intramaterial condensation of electric energy density is observed in semiconductor nano-antennas for certain plasmonic chirp-frequencies which enables broadband high-gain optical amplification based on free-electron oscillations that is promising for small-scale optical devices requiring a high gain-bandwidth product. The results are in good agreement with semiempirical data.

Bi-activated photonic materials are promising for various applications in high-capacity telecommunication, tunable laser, and advanced bioimaging and sensing. Although various Bi-doped material candidates have been explored, manufacturing of Bi heavily doped fiber with excellent optical activity remains a long-standing challenge. Herein, a novel viscosity evolutional behavior mediated strategy for manufacturing of Bi-doped active fiber with high dopant solubility is proposed. The intrinsic relation among the evolution of Bi, reaction temperature and viscosity of the glass system is established. Importantly, the effective avenue to prevent the undesired deactivation of Bi during fiber drawing by tuning the temperature dependent viscosity evolution is built. By applying the strategy, for the first time we demonstrate the success in fabrication of heavily doped Bi active fiber. Furthermore, the principal fiber amplifier device is constructed and broadband optical signal amplification is realized. Our findings indicate the effectiveness of the proposed temperature dependent viscosity mediated strategy for developing novel photonic active fiber, and they also demonstrate the great potential for application in the next-generation high-capacity telecommunication system.

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated Si 3 N 4 microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications. [ABSTRACT FROM AUTHOR]

In this paper, we report a simulation study on the performance enhancement of Praseodymium doped silica fiber amplifiers (PDFAs) in O-band (1270-1350 nm) in terms of small signal gain, power conversion efficiency (PCE), and output optical power by employing bidirectional pumping. The PDFA performance is examined by optimizing the length of Praseodymium doped silica fiber (PDF), its mode-field diameter (MFD) and the concentration of Pr3+. A small-signal peak gain of 56.4 dB, power conversion efficiency (PCE) of 47%, and output optical power of around 1.6 W (32 dBm) is observed at optimized parameters for input signal wavelength of 1310 nm. Minimum noise figure (NF) of 4.1 dB is observed at input signal wavelength of 1310 nm. Moreover, the effect of varying the pump wavelength and pump power on output optical power of the amplifier and amplified spontaneous emission (ASE) noise is also investigated, respectively. Finally, the impact of ion-ion interaction (up-conversion effect) on small-signal gain of the amplifier is also studied by considering different values of up-conversion coefficient. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs) showing a wide‐range tunability in their emission wavelength are promising materials for next‐generation optoelectronic applications. However, there are few studies on optical amplification functionalities for broadband emission of GQDs. Here, the authors demonstrate a broadband optical amplification of GQDs mixed with a polymer matrix. The GQD particles prepared by microwave‐assisted hydrothermal method show a large variation in their dimension and a broadband emission with a large Stokes shift. In a form of polymeric thin film, the GQDs exhibit amplified spontaneous emission (ASE) signal showing the broadband gain of ≈370–650 nm and the gain coefficient up to ≈4 cm–1. Cut‐off mode propagation is the origin of ASE signal generation. The optical amplification performance is found to be associated to the photoluminescence quantum yield, which is improved by the GQDs passivation with the polymer matrix. These results demonstrate that the GQDs are a promising active material as a wideband optical amplification medium. [ABSTRACT FROM AUTHOR]

Optical switching is an essential part of photonic integrated circuits and the focus of research at the moment. In this research, an optical switch design working on the phenomenon of guided-mode resonances in a 3D photonic-crystal-based structure is reported. The optical-switching mechanism is studied in a dielectric slab-waveguide-based structure operating in the near-infrared range in a telecom window of 1.55 µm. The mechanism is investigated via the interference of two signals, i.e., the data signal and the control signal. The data signal is coupled into the optical structure and filtered utilizing guided-mode resonance, whereas the control signal is index-guided in the optical structure. The amplification or de-amplification of the data signal is controlled by tuning the spectral properties of the optical sources and structural parameters of the device. The parameters are optimized first using a single-cell model with periodic boundary conditions and later in a finite 3D-FDTD model of the device. The numerical design is computed in an open-source Finite Difference Time Domain simulation platform. Optical amplification in the range of 13.75% is achieved in the data signal with a decrease in the linewidth up to 0.0079 µm, achieving a quality factor of 114.58. The proposed device presents great potential in the field of photonic integrated circuits, biomedical technology, and programmable photonics.

9,9-bis (diphenylphosphorylphenyl) fluorene (FDPO) and dibenzotetrathienoacene (DBTTA), are synthesized as the neutral and anionic ligands, respectively, to prepare the Er III coordination polymer [Er(DBTTA) 3 (FDPO)] n . Based on the intramolecular energy transfer, optical gains at 1.5 µm are demonstrated in [Er(DBTTA) 3 (FDPO)] n -doped polymer waveguides under excitations of low-power light-emitting diodes (LEDs) instead of laser pumping. A ligand-sensitization scheme between organic ligands and Er 3+ ions under an excitation of an ultraviolet (UV) LED is established. Relative gains of 10.5 and 8.5 dB cm -1 are achieved at 1.53 and 1.55 µm, respectively, on a 1-cm-long SU-8 channel waveguide with a cross-section of 2 × 3 µm 2 and a 1.5-µm-thick [Er(DBTTA) 3 (FDPO)] n -doped polymethylmethacrylate (PMMA) as upper cladding. The Er III coordination polymer [Er(DBTTA) 3 (FDPO)] n can be conveniently integrated with various low-loss inorganic waveguides to compensate for optical losses in the C-band window. Moreover, by relying on the intramolecular energy transfer and UV LED top-pumping technology, it is easy to achieve coupling packaging of erbium-doped waveguide amplifiers (EDWAs) with pump sources in planar photonic integrated chips, effectively reducing the commercial costs., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

This paper proposes an optical amplification method of measuring the minute displacement of a laser beam. The relationship between the displacement of the incident laser beam and the reflective beam is calculated by geometric optical analysis. The equation of displacement is derived to calculate its magnification. We demonstrate that by employing the reflection characteristics of a cylindrical mirror, the minute-displacement of a laser beam can be enlarged to the millimetre level. Experimental results confirm that the magnification can be hundreds of times. Such an enlarged displacement measuring system of laser beam could be suitable for the study of Goos–Hänchen shift. [ABSTRACT FROM AUTHOR]

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated Si3N4 microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications.

Summary: Visible-light communication (VLC) based on white light-emitting diodes has recently attracted much attention to provide high-bitrate data communication in indoor environments. One of the remaining challenges to be resolved to enable the proliferation of VLC systems is related to channel attenuation and multiple path fading. Here, we introduce an advanced VLC system integrating an optical amplifier as a promising solution to overcome channel impairments, providing high bitrate coverage. The optical amplifier is a flexible fiber based on a poly(fluorene)-based lumophore doped within a di-ureasil organic-inorganic hybrid. Optical amplification is demonstrated for pre-amplifier and relay node scenarios, yielding a maximum gain of 5.9 ± 0.2 dB and 3.7 ± 0.2 dB, respectively, establishing the proposed approach as a promising cost-effective solution for VLCs. Additionally, numerical simulations show, for a realistic environment, a 207% improvement in the coverage area, using existing lighting infrastructure without extra cost.

The standard solution for short-haul fiber-optic communications is to deploy noncoherent systems, i.e., to modulate and detect only the light intensity. In such systems, the signal is corrupted with optical noise from amplifiers and with thermal (electrical) noise. The capacity of noncoherent optical links has been studied extensively in the presence of either optical noise or thermal noise. In this paper, for the first time, we characterize the capacity under an average power constraint with both noise sources by establishing upper and lower bounds. In the two extreme cases of zero optical noise or zero thermal noise, we assess our bounds against some well-known results in the literature; improvements in both cases are observed. Next, for amplified fiber-optic systems, we study the trade-off between boosting signal energy (mitigating the effects of thermal noise) and adding optical noise. For a wide spectrum of system parameters and received power levels, we determine the optimal amplification gain. While mostly either no amplification or high-gain amplification is optimal, the best performance is for some parameter intervals achieved at finite gains. [ABSTRACT FROM AUTHOR]

A wide range of highly–relevant problems in programmable and integrated photonics, optical amplification, and communication deal with inverse system design. Typically, a desired output (usually a gain profile, a noise profile, a transfer function or a similar continuous function) is given and the goal is to determine the corresponding set of input parameters (usually a set of input voltages, currents, powers, and wavelengths). We present a novel method for inverse system design using machine learning and apply it to Raman amplifier design. Inverse system design for Raman amplifiers consists of selecting pump powers and wavelengths that would result in a targeted gain profile. This is a challenging task due to highly–complex interaction between pumps and Raman gain. Using the proposed framework, highly–accurate predictions of the pumping setup for arbitrary Raman gain profiles are demonstrated numerically in C and C+L–band, as well as experimentally in C band, for the first time. A low mean (0.46 and 0.35 dB) and standard deviation (0.20 and 0.17 dB) of the maximum error are obtained for numerical (C+L–band) and experimental (C–band) results, respectively, when employing 4 pumps and 100 km span length. The presented framework is general and can be applied to other inverse problems in optical communication and photonics in general. [ABSTRACT FROM AUTHOR]

A theoretical study has been performed on 1.76 μm on-chip amplification characteristics of Tm3+ in a rib waveguide of LiNbO 3 on insulator (Tm:LNOI) under 795 nm wavelength pumping. Steady-state rate equations and propagation equations of signal and pump waves are established on the basis of a three-level model of Tm3+ system with the cross relaxation process 3H 4 →3F 4 : 3H 6 →3F 4 included. The validity of the three-level model is demonstrated by referencing previously reported experiment result of Er3+-doped LNOI waveguide amplifier and by examining the effect of Tm3+ blue upconversion emissions on the 1.76 μm amplification. Besides the relations of signal gain to propagation length, launched pump power and input signal power, the effects of waveguide cross-section geometry and Tm3+ concentration on the gain characteristics are also studied. The results show that the waveguide cross-section geometry affects definitely the gain performance via its effect on mode field. The Tm3+ concentration affects the signal gain also via its effect on the 3H 4 →3F 4 : 3H 6 →3F 4 cross relaxation coefficient, besides the conventional effect that higher active ion concentration yields larger signal gain. A comparison with conventional Ti4+(Zn2+)-diffused Tm3+-doped LN [Ti(Zn):Tm:LN] waveguide shows that the Tm:LNOI waveguide has much better gain performance than the Ti(Zn):Tm:LN waveguide, including much stronger pump power and propagation distance dependences of signal gain, much higher signal gain and much lower threshold pump power. These features are associated with significantly increased Tm3+ population inversion extent due to ultra-compact mode field and larger overlapping factor of mode field and Tm3+ population profiles in the Tm:LNOI waveguide. • 1.8 μm amplification in Tm:LNOI waveguide is simulated based on three-level model. • Quantitative relations of signal gain to controllable parameters are established. • Tm:LNOI amplifier is more efficient than Ti(Zn):Tm:LN due to ultra-compact mode. • Waveguide cross-section geometry affects definitely gain via its effect on mode field. • Tm3+ concentration affects gain via its effect on cross relaxation process. [ABSTRACT FROM AUTHOR]

We present results for the performance of a pre-amplified optical pulse-position modulation (PPM) receiver that utilizes the low-density parity-check (LDPC) correction codes of the 5G standard. The code construction is suitable for correcting burst errors that are introduced by PPM. Simulation results show that the LDPC codes can provide a very significant real gain, provided that the code rate is chosen appropriately. We find that the code rates that minimize the bit-error-probabilities (BEPs) of the system range between 2 / 3 and 22 / 26 , with higher code rates being required in receivers that operate under increased optical noise. It is also shown that a comparable real gain is obtained for both the sum–product and min-sum decoders, while the power penalty of the latter one is only limited to 0.2 dB, when the aforementioned code rates are utilized. [ABSTRACT FROM AUTHOR]

• On-chip 1.53 μm amplification in Er:LNOI micro-photonic amplifier was simulated. • The simulation was performed in comparison with Ti:Er:LiNbO 3 waveguide amplifier. • Numerical model is confirmed by consistency of numerical and experimental results. • The Er:LNOI amplifier is more efficient than the Ti:Er:LiNbO 3 waveguide. • Due to higher Er3+ population inversion extent and ultra-compact mode of Er:LNOI. On-chip 1.53 μm amplification in 980-nm-pumped Er3+-doped lithium niobate on insulator (Er:LNOI) photonic wire (PW) has been studied theoretically in comparison with that in Ti:Er:LiNbO 3 waveguide on the basis of three- and six-level models of Er3+. We show that the six-level model gives more accurate analysis and its validity is confirmed by comparing the simulated results with the previously reported experiment data. The study shows that the Er:LNOI PW has a larger Er3+ population inversion extent than the Ti:Er:LiNbO 3 because of larger overlapping factor of mode field and Er3+ population profiles, and ultra-compact mode field. As a result, the Er:LNOI PW displays better gain performance than the Ti:Er:LiNbO 3 as described below. (1) Maximum/saturation gain of Er:LNOI PW can be as much as two/three times higher than that of the Ti:Er:LiNbO 3. (2) Gain of the Er:LNOI PW increases with propagation length more strongly in the initial stage and decreases more slowly beyond optimal length. It also shows stronger dependences on both pump power (in the initial stage) and signal power. (3) Gain in the Er:LNOI PW saturates more easily, and the Er:LNOI PW has a threshold pump power one order of magnitude lower than the Ti:Er:LiNbO 3. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has made it abundantly clear that the state-of-the-art biosensors may not be adequate for providing a tool for rapid mass testing and population screening in response to newly emerging pathogens. The main limitations of the conventional techniques are their dependency on virus-specific receptors and reagents that need to be custom-developed for each recently-emerged pathogen, the time required for this development as well as for sample preparation and detection, the need for biological amplification, which can increase false positive outcomes, and the cost and size of the necessary equipment. Thus, new platform technologies that can be readily modified as soon as new pathogens are detected, sequenced, and characterized are needed to enable rapid deployment and mass distribution of biosensors. This need can be addressed by the development of adaptive, multiplexed, and affordable sensing technologies that can avoid the conventional biological amplification step, make use of the optical and/or electrical signal amplification, and shorten both the preliminary development and the point-of-care testing time frames. We provide a comparative review of the existing and emergent photonic biosensing techniques by matching them to the above criteria and capabilities of preventing the spread of the next global pandemic.

• Propose a method for reducing optical loss in resonant structures. • It consists on replacing SiO 2 top claddings in Si waveguides by erbium-doped Al 2 O 3. • Experimental results show loss reduction of up to 2.6 dB in photonic molecules. • Demonstrates potential for high Q, low-loss and compact foundry-made devices. Silicon photonics routers and band-pass filters employing ring resonators are usually constrained by a trade-off between quality factors and insertion loss, which is even more pronounced in compact designs. Device real estate is another factor to be considered for compactness and cost reduction. We propose an approach to simultaneously reduce insertion losses and increase the quality factor in such devices, while minimizing footprint. This approach consists in replacing the standard SiO 2 top cladding of Si devices by erbium-doped Al 2 O 3 films with a single post-processing step. Experimental results confirm the effectiveness of the method, where 1 dB output power increase is observed for a single ring device, in addition to an increase of 5% in the Q factor. In some cases of structures comprised of multiple coupled resonators, i.e., photonic molecules, the observed value of power increase is as high as 2.6 dB, with a Q factor increase of 25% and loss reduction of 3 dB. [ABSTRACT FROM AUTHOR]

Abstract Ordering properties of a scattering media plays important role in a lasing emission system. In this work, we report a comparison study of optical amplification and lasing action from well aligned and randomly oriented dye doped polymeric nanofibers. Parallel aligned and randomly oriented dye doped polymeric nanofibers were prepared by electrospinning. Different optical phenomenon has been obtained from such two type fiber systems: amplified spontaneous emission from the well aligned nanofibers, and multimode random lasing emission with many sharp peaks from the randomly oriented nanofibers. To evaluate the effect of the microcavity effect, we carry out a comparative study of the optical pumped emission, threshold, and polarization properties of the two systems. Based on the comparison results, we try to discuss the mechanism for the optical cavity formation, where packing arrangement of the fibers plays a key role in the luminescence mechanism. Our comparative study of emission properties from well aligned and randomly oriented fibers manifest that the essence of random lasing is a highly disordered gain medium. Graphical abstract Image 1 Highlights • Parallel aligned and randomly oriented dye doped polymeric nanofibers were prepared by electrospinning. • A comparison study of lasing action from aligned and randomly oriented nanofibers was performed. • ASE from well aligned nanofibers and random lasing emission from the randomly oriented nanofibers. [ABSTRACT FROM AUTHOR]

Commercial light‐emitting diodes are a low‐cost and energy‐efficient solution for the implementation of optical wireless communication, known as visible light communication (VLC). This technology has a huge growing interest, being recently a research spotlight in the scientific community, especially due to the increasing popularity and rapid development of self‐sustainable smart houses and the Internet of Things. As the VLC link is free space, big challenges arise in its implementation. To improve the VLC performance, this work proposes an enhanced system solution integrating an optical amplifier. In this context, organic–inorganic hybrids incorporating a blue‐emitting conjugated polymer with high quantum yield (>50%) were synthesised and processed as planar waveguides. The waveguides were tested in a testbed scenario, showing a signal amplitude improvement of 2.5 dB, establishing the proposed approach as a promising cost‐effective solution for optical amplification in VLCs. [ABSTRACT FROM AUTHOR]

Nitrogen ions pumped by intense femtosecond laser pulses present an optical gain at 391.4 nm, evident by energy amplification of an injected resonant seeding pulse. We report a time-resolved measurement of the amplification process with seeding pulses having varying intensities. It is found that the amplification factor depends on the intensity of the seeding pulse and the effective temporal window for the optical gain becomes longer by applying more intense seeding pulses. These two features are in sharp contrast with classic pump-probe experiments, pinpointing the crucial role of macroscopic coherence and its dynamics during the lasing process. We further measure the temporal profile of the amplified emission for seeding pulse injected at different time delays. A complicated temporal behavior is observed, which highlights the nature of the superfluorescence.

The achievement of wideband high-gain optical parametric amplification has not been shown in micrometer-scale cavities. In this paper we have computationally investigated the optical parametric amplification process in a few micrometer-long dispersive microresonator. By performing a gain medium resonance frequency dependent analysis of optical parametric amplification, we have found that it is possible to achieve a wideband high-gain optical amplification in a dispersive microresonator. In order to account for the effects of dispersion (modeled by the polarization damping coefficient) and the resonance frequency of the gain medium on optical parametric amplification, we have solved the wave equation in parallel with the nonlinear equation of electron cloud motion, using the finite difference time domain method. Then we have determined the resonance frequency values that yield an enhanced or a resonant case of optical parametric amplification, via gain factor optimization. It was observed that if the microresonator is more dispersive (has a lower polarization damping coefficient), then there are more resonance frequencies that yield an optical gain resonance. At these gain resonances, a very wideband, high-gain optical amplification seems possible in the micron scale, which, to our knowledge, has not been previously reported in the context of nonlinear wave mixing theory.

Intense ∼1.2 μm fluorescence is observed in Ho 3+ /Yb 3+ co-doped TeO 2 -BaF 2 -Y 2 O 3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5 I 6 → 5 I 8 of Ho 3+ . With the introducing of BaF 2 , the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF 2 . Furthermore, microstructured fibers based on the TeO 2 -BaF 2 -Y 2 O 3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber. [ABSTRACT FROM AUTHOR]

Modern electronics are developing electronic-optical integrated circuits, while their electronic backbone, e.g. field-effect transistors (FETs), remains the same. However, further FET down scaling is facing physical and technical challenges. A light-effect transistor (LET) offers electronic-optical hybridization at the component level, which can continue Moore’s law to quantum region without requiring a FET’s fabrication complexity, e.g. physical gate and doping, by employing optical gating and photoconductivity. Multiple independent gates are therefore readily realized to achieve unique functionalities without increasing chip space. Here we report LET device characteristics and novel digital and analog applications, such as optical logic gates and optical amplification. Prototype CdSe-nanowire-based LETs show output and transfer characteristics resembling advanced FETs, e.g. on/off ratios up to ~1.0x106 with a source-drain voltage of ~1.43 V, gate-power of ~260 nW, and subthreshold swing of ~0.3 nW/decade (excluding losses). Our work offers new electronic-optical integration strategies and electronic and optical computing approaches.

In this article, we present the modeling of an optical communication link using the optical standard single-mode fiber working at X = 1.55 џт single wavelength The simulation confirmed the experimental characteristics like the photo detector sensibility, bit error rate (BER), the eye pattern, as well as the limitations and the performance of such optical transmission system.

Quantum dot-doped glasses have been the hotspot for their excellent electronic and optical properties. Owing to its tunable and broadband near-infrared (NIR) emission by controlling the size and distribution of QDs, QD-doped glasses and fibers are potentially applied in photoelectric devices. In this review, we mainly introduce the preparation, tunable emission, and multi-wavelength optical amplification of QD-doped glasses. Due to their excellent optical performances, the fabrication of QD-doped glass fibers is also presented, containing the successful fabrication of QD-doped glass fibers with tunable NIR emission. Furthermore, the achievements and existing problems about QD-doped glasses and fibers are also proposed with several prospects. These QD-doped glasses and fibers show promising applications as the gain medium of NIR broadband fiber amplifiers and tunable fiber lasers.

We have demonstrated an optical amplification of hot electron light emitting and lasing in semiconductor heterostructure (HELLISH) vertical-cavity semiconductor optical amplifiers (VCSOAs) at wavelength operation of $${\lambda=1.29\,{\rm \mu}{\rm m}}$$ . These devices were characterized using optical pumping, electrical pumping and optical-electrical pumping. HELLISH-VCSOA device of 500-μm contact separation is a surface emitter based on longitudinal injection of electron and hole pairs in their respective channels. Dilute nitride GaInNAs/GaAs is used as an active material for operation in the $${\lambda=1.3-{\rm \mu}{\rm m}}$$ window of the optical communications. The device has undoped distributed Bragg reflectors (DBRs), and the current is injected longitudinally into the active layers without passing through DBRs. The issues are associated with refractive index contrast, and current injections through the DBR layers are avoided. [ABSTRACT FROM AUTHOR]

In this study, a new method for increasing simultaneously the sensitivity and interrogation stability of fiber-optic intensity sensors is presented. The configuration is based on a double-coupler ring resonator. On one side, the attenuation sensitivity of the sensor is enhanced by placing it inside a ring resonator. On the other side, the stability of the interrogation method is widely improved by creating an external lasing ring resonator with matched spectral response. The combination of the wavelength selective response of the ring resonator and optical amplification from Er-doped fiber amplifier is used to create different fiber lasers. The resulting lasers present an impressive sensitivity enhancement and a dynamic range increment up to 15 dB. Simultaneously, the instability of the system is reduced to ±0.05 dB. In comparison with systems based on tunable laser interrogation, our method is >100 times more stable and also simpler, as no wavelength tunable elements are required. [ABSTRACT FROM PUBLISHER]

The photorefractive effect in ferroelectric liquid crystalline mixtures containing photoconductive chiral compounds was investigated. Ter-thiophene compounds with chiral structures were chosen as the photoconductive chiral compounds, and they were mixed with an achiral smectic C liquid crystal. The mixtures exhibit the ferroelectric chiral smectic C phase. The photorefractivity of the mixtures was investigated by two-beam coupling experiments. It was found that the ferroelectric liquid crystals containing the photoconductive chiral compound exhibit a large gain coefficient of over 1200 cm−1and a fast response time of 1 ms. Real-time dynamic amplification of an optical image signal of over 30 fps using the photorefractive ferroelectric liquid crystal was demonstrated. [ABSTRACT FROM PUBLISHER]