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A holographic optical waveguide (HOW) is an optimal solution for augmented reality (AR) displays, in which reflection volume holographic gratings are core optical elements. In this study, five high‐refractive‐index (≈1.6) bifunctional acrylate monomers (TPBSAs) are designed and synthesized. A series of two‐stage photopolymers are prepared using TPBSAs as writing monomers. Among them, one containing 9 wt.% TPBSA‐3 shows the best holographic recording performance with a sensitivity as high as 26.59 cm mJ−1. Using it as the recording medium, a reflection VHG can be obtained with high spatial frequency (5634 lines per mm), diffraction efficiency (97.14%), refractive index modulation (0.029), and good transparency within 400−800 nm after photobleaching. Furthermore, a HOW capable of achieving virtual and real image fusion is fabricated. [ABSTRACT FROM AUTHOR]

Silicon‐based on‐chip broadband surface‐enhanced infrared absorption (SEIRA) is highly desired for integrated micromolecular detection systems, taking advantages of CMOS mass production, low cost, high sensitivity, etc. However, the silicon platform is difficult to operate in the mid‐infrared wavelength region above 4 µm where abundant fingerprint characteristics of biomolecules are located, because of the strong absorptions in silicon dioxide cladding above 4 µm. Here, a large‐core rib silicon waveguide‐integrated gradient nanoantenna array is proposed for broadband long‐wave infrared biomolecular detection. It is shown that Low loss propagation of light in the long‐wave infrared region up to 7 µm (1428 cm−1) in silicon photonics can be achieved while avoiding complex fabrication techniques. A gradient nanoantenna array is designed on the waveguide to achieve broadband enhancement from 5 to 7 µm (1428–2000 cm−1). Laser spectroscopy of bovine serum albumin on the chip is demonstrated, showing enhancement of absorbance by approximately ten times over laser transmission spectroscopy in the amide bands. Such a platform opens up a new horizon of silicon‐based on‐chip SEIRA biomolecular detection. [ABSTRACT FROM AUTHOR]

Organoboron compounds offer a new strategy to design optoelectronic materials with high fluorescence efficiency. In this paper, the organoboron compound B‐BNBP with double B←N bridged bipyridine bearing four fluorine atoms as core unit is facilely synthesized and exhibits a narrowband emission spectrum and a high photoluminescence quantum yield (PLQY) of 86.53 % in solution. Its polymorphic crystals were controllable prepared by different solution self‐assembly methods. Two microcrystals possess different molecular packing modes, one‐dimensional microstrips (1D‐MSs) for H‐aggregation and two‐dimensional microdisks (2D‐MDs) for J‐aggregation, owing to abundant intermolecular interactions of four fluorine atoms sticking out conjugated plane. Their structure‐property relationships were investigated by crystallographic analysis and theoretical calculation. Strong emission spectra with the full width at half maximum (FWHM) of less than 30 nm can also be observed in thin film and 2D‐MDs. 1D‐MSs possess thermally activated delayed fluorescence (TADF) property and exhibit superior optical waveguide performance with an optical loss of 0.061 dB/μm. This work enriches the diversity of polymorphic microcrystals and further reveals the structure‐property relationship in organoboron micro/nano‐crystals. [ABSTRACT FROM AUTHOR]

This paper explores the propagation loss in waveguides on directly bonded InP/Si substrates, using numerical simulations to understand the effect of voids within the waveguide structure. Using COMSOL Multiphysics, we developed a model to simulate light propagation, focusing on how void characteristics such as diameter and angle influence the propagation loss. Our findings reveal a correlation between void dimensions and the increased threshold current density in separate confinement heterostructure multiple quantum well laser diodes, thereby providing insights into optimizing waveguide design for enhanced laser performance on InP/Si substrates. This research underscores the critical role of substrate bonding quality in minimizing internal losses and improving device efficiency. [ABSTRACT FROM AUTHOR]

Ultrafast lasers, characterized by femtosecond and picosecond pulse durations, have revolutionized material processing due to their high energy density and minimal thermal diffusion, and have played a transformative role in precision manufacturing. This review first traces the progression from early ruby lasers to modern titanium–sapphire lasers, highlighting breakthroughs like Kerr-lens mode-locking and chirped pulse amplification. It also examines the interaction mechanisms between ultrafast pulses and various materials, including metals, dielectrics, and semiconductors. Applications of ultrafast lasers in microstructure processing techniques are detailed, such as drilling, cutting, surface ablation, and nano welding, demonstrating the versatility and precision of the technology. Additionally, it covers femtosecond laser direct writing for optical waveguides and the significant advancements in imaging and precision measurement. This review concludes by discussing potential future advancements and industrial applications of ultrafast lasers. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Organic heterostructures (OHs) with multi‐segments exhibit special optoelectronic properties compared with monomeric structures. Nevertheless, the synthesis of multi‐block heterostructures remains challenging due to compatibility issues between segment parts, which restricts their application in optical waveguides and integrated optics. Herein, we demonstrate programmable in‐situ co‐assembly engineering, combining multi‐step spontaneous self‐assembly processes to promote the synthesis of multi‐block heterostructures with a rational arrangement of three or more segments. The rational design of segments enables exciton manipulation and ensures optical waveguides and proper output among the multi‐segment OHs. This work enables the controllable growth of segments within multi‐block OHs, providing a pathway to construct complex OHs for the rational development of future optical applications. [ABSTRACT FROM AUTHOR]

An optical waveguide that transmits the electromagnetic waves is a critical component for various optoelectrical applications including integrated optical circuits and optical communications. Among many, the 1D tubular optical waveguide structure enables efficient distant energy transfer via mode selection within the optical microcavity. However, its application is limited due to the complicated fabrication process. Herein, hexagonal tris(8‐hydroxyquinoline) aluminum (Alq3) microtubes with an average longitudinal length of ≈15 µm are self‐assembled within few minutes by utilizing 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquids. The swift fabrication is enabled by the high electron affinity of BMIMBF4 that forms hexagonal microrods. Also, BMIMBF4 ionic liquid etches the central region of micorods during its growth, forming microtubes with a wall thickness of ≈650 nm. The fabricated Alq3 microtubes show significantly improved waveguide characteristics with reduced optical loss coefficient (0.054 µm−1) compared to that of microrods (0.271 µm−1). The demonstrated method to fabricate Alq3 microtubes with ionic liquid is an efficient approach to utilize organic microstructures as an optoelectrical components for advanced optical communications. [ABSTRACT FROM AUTHOR]

Ultrashort pulse laser provides an efficient way to fabricate integrated photonic devices by modulating the refractive index of optical materials with nonlinear absorption to form three-dimensional optical waveguides. Er3+-doped phosphate glass, due to its excellent characteristics and emission spectrum in the communication band near 1.55 μm, has become a research hotspot in integrated optical active gain materials. In the experiment, the Ti: sapphire femtosecond laser amplification system with the output pulse laser parameters of repetition frequency of 1 kHz, center wavelength of 800 nm and pulse width of 120 fs was used as the inscribed light source. The impact of processing parameters on waveguide formation, waveguide morphology and optical properties were systematically studied. The experimental results show that under the transverse writing condition with slit shaping assisted short focus microscope objective, with a fixed pulse energy of 1.8 μJ, the optical waveguide can be formed in the scan speed range of 10 μm/s-160 μm/s. With a fixed scan speed of 40 μm/s, the writing pulse energy window of the optical waveguide is 1.6 μJ-2.0 μJ. The waveguide cross-section is symmetrical and the refractive index is obviously modified, within the depth range of 125 μm-200 μm from the surface. The near-field intensity measurement results show that the near-field intensity distribution of the prepared waveguide is symmetrical, and the light guiding characteristics are maintained well. The refractive index modification distribution in the waveguide region is simulated based on the finite difference method, and the results show that the maximum refractive index modification value is Δn=6.6×10-4. The results of cut-back measurement show that the lowest waveguide propagation loss is only 0.91 dB/cm. [ABSTRACT FROM AUTHOR]

This study introduces the design of a nonlinear frequency-modulated continuous wave (FMCW) laser ranging system. In contrast to the commonly used triangular wave linear modulation, this study utilizes sinusoidal wave modulation. The frequency information of the original sinusoidal frequency-modulated signal is extracted using an on-chip interferometer based on SiON waveguides and IQ demodulation technology. After fitting the measured interference signal at equal frequency intervals, the corresponding distance information is derived using the fast Fourier transform (FFT). The principles underlying this method are thoroughly analyzed and derived, with its accuracy confirmed through experimental validation. [ABSTRACT FROM AUTHOR]

Exploration of efficient red emitting antimony hybrid halide with large Stokes shift and zero self‐absorption is highly desirable due to its enormous potential for applications in solid light emitting, and active optical waveguides. However, it is still challenging and rarely reported. Herein, a series of (TMS)2SbCl5 (TMS=triphenylsulfonium cation) crystals have been prepared with diverse [SbCl5]2− configurations and distinctive emission color. Among them, cubic‐phase (TMS)2SbCl5 shows bright red emission with a large Stokes shift of 312 nm. In contrast, monoclinic and orthorhombic (TMS)2SbCl5 crystals deliver efficient yellow and orange emission, respectively. Comprehensive structural investigations reveal that larger Stokes shift and longer‐wavelength emission of cubic (TMS)2SbCl5 can be attributed to the larger lattice volume and longer Sb⋅⋅⋅Sb distance, which favor sufficient structural aberration freedom at excited states. Together with robust stability, (TMS)2SbCl5 crystal family has been applied as optical waveguide with ultralow loss coefficient of 3.67 ⋅ 10−4 dB μm−1, and shows superior performance in white‐light emission and anti‐counterfeiting. In short, our study provides a novel and fundamental perspective to structure‐property‐application relationship of antimony hybrid halides, which will contribute to future rational design of high‐performance emissive metal halides. [ABSTRACT FROM AUTHOR]

Grating couplers are widely used to couple waveguide modes with the far field. Their usefulness is determined not only by energy efficiency but also by additional supported functionality. In this paper, a plasmonic is demonstrated grating on a silicon nitride slab waveguide that couples both transverse electric (TE) and transverse magnetic (TM) waveguide modes with circularly polarized light in the far field. Specifically, it is experimentally confirmed that circularly polarized light excites TE and TM modes propagating in opposite directions, and the direction is controlled by the handedness. The routing efficiency for normally incident light reaches up to 95%. The same structure operates in the outcoupling regime as well, demonstrating up to 97% degree of circular polarization, where the handedness is determined by the polarization and propagation direction of outcoupled modes. The results pave the way for the realization of polarization‐division multiplexers and demultiplexers, integrated circular polarization emitters, as well as detectors of the polarization state of the incident optical field. [ABSTRACT FROM AUTHOR]

In this paper, the dispersion characteristics of slotted photonic crystal waveguides (SPCWs) have been estimated for any arbitrary set of structural parameters using machine learning-based artificial neural network (ANN). The machine learning-based technique yields faster solutions of the three-dimensional eigenvalue equations, which otherwise require substantial time using the conventional plane wave expansion (PWE)-based numerical simulations. Most importantly, the novel contribution of the work lies in estimating the structural parameters of the SPCWs from the given specifications of the dispersion characteristics through an inverse computation. A simple feed-forward neural network has been employed for both the forward and inverse estimations. The computation performances using both the ANN model and PWE simulations are analyzed and compared. The research offers significant implications for the field of photonics. By employing machine learning techniques, particularly ANNs, researchers and engineers can swiftly and efficiently analyze the dispersion properties of SPCWs, facilitating rapid prototyping and optimization of photonic devices. Additionally, the capability to infer structural parameters from desired dispersion characteristics streamlines the design process, potentially leading to the development of customized waveguides tailored to specific applications. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency. Compact, integrated optical switches are attractive thanks to their scalability, readiness for mass production, and robustness against mechanical disturbances. The basic unit relies mostly on a microring resonator or a Mach–Zehnder interferometer for binary “bar” and “cross” switching. Such single-mode structures are often wavelength / polarization dependent, sensitive to phase errors and loss-prone. Furthermore, when they are cascaded to a network, the number of control units grows quickly with the port count, causing high complexity in electronic wiring and drive circuit integration. Herein, we propose a new switching method by thermo-optic waveguide lens. Essentially, this multimode waveguide forms a square law medium by a pair of heater electrodes and focuses light within a chip by robust 1 × 1 imaging. A 1 × 24 basic switch is demonstrated with 32 electrodes and only two are biased at a time for a chosen output. By two-level cascading, the switch expands to 576 ports and only four electrodes are needed for one path. The chips are fabricated on wafer scale in a low-budget laboratory without resorting to foundries. Yet, the performance goes beyond state of the art for low insertion loss, low wavelength dependence and low polarization dependence. This work provides an original, alternative, and practical route to construct large-scale optical switches, enabling broad applications in telecom, datacom and photonic computing.

High‐quality‐factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100‐nm critical feature size in the coupling region. In this work, a new method "damascene soft nanoimprinting lithography" is demonstrated that can create high‐fidelity waveguide by simply backfilling an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q‐factor polymer microring resonators (e.g., ≈5 × 105 around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q‐factors can be attributed to the residual layer‐free feature and controllable meniscus cross‐section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator. [ABSTRACT FROM AUTHOR]

Ensuring information security has emerged as a paramount concern in contemporary human society. Substantial advancements in this regard can be achieved by leveraging photonic signals as the primary information carriers, utilizing photonic logical gates capable of wavelength tunability across various time and spatial domains. However, the challenge remains in the rational design of materials possessing space‐time‐color multiple‐resolution capabilities. In this work, a facile approach is proposed for crafting metal‐organic halides (MOHs) that offer space‐time‐color resolution. These MOHs integrate time‐resolved room temperature phosphorescence and color‐resolved excitation wavelength dependencies with both space‐resolved ex situ optical waveguides and in situ heterojunctions. Capitalizing on these multifaceted properties, MOHs‐based two‐dimensional (2D) optical waveguides and heterojunctions exhibit the ability to tune full‐color emissions across the spectra from blue to red, operating within different spatial and temporal scales. Therefore, this work introduces an effective methodology for engineering space‐time‐color resolved MOH microstructures, holding significant promise for the development of high‐density photonic logical devices. [ABSTRACT FROM AUTHOR]

Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency. Compact, integrated optical switches are attractive thanks to their scalability, readiness for mass production, and robustness against mechanical disturbances. The basic unit relies mostly on a microring resonator or a Mach–Zehnder interferometer for binary "bar" and "cross" switching. Such single-mode structures are often wavelength / polarization dependent, sensitive to phase errors and loss-prone. Furthermore, when they are cascaded to a network, the number of control units grows quickly with the port count, causing high complexity in electronic wiring and drive circuit integration. Herein, we propose a new switching method by thermo-optic waveguide lens. Essentially, this multimode waveguide forms a square law medium by a pair of heater electrodes and focuses light within a chip by robust 1 × 1 imaging. A 1 × 24 basic switch is demonstrated with 32 electrodes and only two are biased at a time for a chosen output. By two-level cascading, the switch expands to 576 ports and only four electrodes are needed for one path. The chips are fabricated on wafer scale in a low-budget laboratory without resorting to foundries. Yet, the performance goes beyond state of the art for low insertion loss, low wavelength dependence and low polarization dependence. This work provides an original, alternative, and practical route to construct large-scale optical switches, enabling broad applications in telecom, datacom and photonic computing. [ABSTRACT FROM AUTHOR]

In this paper, an all optical 4–2 encoder based on triangular lattice Photonic Crystal structure is proposed. The proposed structure consists of three micro-cavity resonators placed next to each other, resonates at the operating wavelength of 1550 nm to perform the encoder logical operation. The normalized output power for ON state is above 28%, and OFF state is below 0.9%. The minimum time delay and the bit rate of the proposed encoder are about 800 fs and 1.25 Tb/s, respectively. The total footprint of the proposed encoder is around 125 µm2. [ABSTRACT FROM AUTHOR]

Several types of silicon-nanowire-based optical demultiplexers (DeMUXs) for use in short-reach targeted datacenter applications were proposed and their spectral responses were experimentally verified. First, a novel 100-GHz-spaced 16λ polarization-diversified optical DeMUX consisting of 2λ delayed interferometer (DI) type interleaver and 8λ arrayed waveguide gratings will be discussed in the spectral regimes of C-band, together with experimental characterizations showing static and dynamic spectral properties. Second, a novel 800-GHz-spaced 8λ optical DeMUX was targeted for use in LR (long reach) 400 Gbps Ethernet applications. Based on multiple cascade-connected DIs, by integrating the extra band elimination cutting area, discontinuous filtering response was analytically identified with a flat-topped spectral window and a low spectral noise of <−20 dB within an entire LR-8 operating wavelength range. Finally, a 20-nm-spaced 4λ coarse wavelength division multiplexing (CWDM)-targeted optical DeMUX based on polarization diversity was experimentally verified. The measurement results showed a low excessive loss of 1.0 dB and a polarization-dependent loss of 1.0 dB, prominently reducing spectral noises from neighboring channels by less than −15 dB. Moreover, TM-mode elimination filters were theoretically analyzed and experimentally confirmed to minimize unwanted TM-mode-oriented polarization noises that were generated from the polarization-handling device. The TM-mode elimination filters functioned to reduce polarization noises to much lower than −20 dB across the entire CWDM operating window. [ABSTRACT FROM AUTHOR]

Structurally novel fluorinated polyurethaneimide (PUI) electro-optic polymer based on chromophore molecule b, diisocyanate MDI and anhydride BPAFDA was synthesized by stepwise polymerization of oligomer PUI with fluorinated aromatic diamines BATB and BATPP. Electro-optic (EO) PUI chain structure had the structure of polyimide and polyurethane chain segments, integrating the advantages of polyimide and polyurethane. The PUI possessed good film-forming property, a high glass transition temperature (Tg = 193 °C) and good thermal stability (5 % weight loss temperature Td up to 320 °C). Y-Structured inverted ridge polymer optical waveguides were designed and fabricated using the PUI as the waveguide core material. The PUI had good optical performance with an EO coefficient (γ33) of 79 pm/V and 1.1 dB/cm optical propagation loss at a wavelength of 1550 nm. The results showed that the synthesized PUI met the performance requirements for the preparation of polymer optical waveguide devices and was suitable as a polymer electro-optic waveguide material. [ABSTRACT FROM AUTHOR]

In optical processing systems, multiplexer is used to design optical devices such as arithmetic logic unit (ALU) and shift register (SR). Through this paper, we investigate the application of nonlinear photonic crystal ring resonator (PhCRR) based on nonlinear Kerr effect for realizing an all optical 2 × 1 multiplexer. The structure consists of two PhCRRs and five optical waveguides using hexagonal lattice silicon (Si) rods with a background of air. Performance of all optical 2 × 1 multiplexer is replicated with the help of finite difference time domain (FDTD) procedure at a wavelength of 1571 nm, and simulations presented an ultra-compact optical structure with ultra-fast switching speed. [ABSTRACT FROM AUTHOR]

The development of high‐performance organic blue light‐emitting emitters is in urgent to act as an excitation source to contribute the white light generation. On the other hand, the investigation on optical waveguides have been received increasing attentions because they can manipulate the light propagation accurately in the microscale to boost the optoelectronic and energy conversion applications. In this work, we facilely prepared a deep‐blue aggregation‐induced emission (AIE) dye, namely TPP‐4OMe, which shows high luminescent efficiency, narrow emission band and good stability in the aggregate state. TPP‐4OMe can be fabricated as deep‐blue AIE microfibers readily with definite morphology and composition. Based on the AIE microfibers, the active waveguide to transmit deep‐blue emission signals can be achieved with a very low optical loss coefficient (α) of 6.7 × 10−3 dB μm−1. Meanwhile, the full‐visible broadband low‐loss passive waveguide can be well performed with these AIE microfibers, which has never been observed in the pure organic crystals. More interestingly, the excellent properties of AIE microfibers enable them to act as a wave‐guiding excitation source, resulting in a distinct and pure white light emission. The present work not only provides excellent blue light‐emitting materials but also bridges the waveguide to realize the efficient white light emission to accelerate the practical applications. [ABSTRACT FROM AUTHOR]

The high-quality waveguide structure in the Dy 3 + -doped Y3Al5O 1 2 transparent ceramic is of significance for the application of integrated micro-light elements. However, there have been no reports on the preparation of optical waveguides by ion implantation in the Dy 3 + -doped Y3Al5O 1 2 transparent ceramic. The work reports on the formation of optical planar waveguides by using the proton implantation in the Dy 3 + -doped Y3Al5O 1 2 transparent ceramic. The acceleration energy and the dose of the protons are 400 keV and 8 × 1 0 1 6 ions/cm2, respectively. The structure of the fabricated waveguide is captured with the high-res/mag images by a metallurgical microscope. The dark-mode spectrum and the refractive index distribution are gained by the prism coupling system and the RCM software, respectively. The measurement and simulation of the near-field intensity distribution indicate the propagation of light field in the waveguide. The results are of potential to the compact devices in the photonics. [ABSTRACT FROM AUTHOR]

In this study, the gas pressure dependence of optical and mechanical characteristics in reactive sputtered SiCO thin films for optical guided‐wave pressure sensors was experimentally investigated. Thin films were fabricated by varying the gas pressure from 0.3 to 1.0 Pa at an oxygen flow ratio of 6%, and the gas pressure dependences was clarified. As the gas pressure increased, the optical bandgap of the SiCO thin film increased, resulting in a transparent SiCO films. On the other hand, the refractive index, young's modulus, and hardness decreased with increasing gas pressure. Combining this dependence with the oxygen inflow ratio dependence of the previous study, the first‐order approximation formula for the gas pressure and oxygen flow rate ratio for various film characteristics was obtained. Based on this equation, trajectories of equal bandgaps and equal young's moduli on the oxygen flow ratio—gas pressure plane were created on the oxygen influx ratio‐gas pressure coordinates, making it easy to fabricate waveguides with desired characteristics. [ABSTRACT FROM AUTHOR]

In this paper, the semi-cladding waveguides with diameters of 30, 40 and 50 μm were successfully prepared in lithium niobate (LiNbO3) crystals by femtosecond laser micro-nano-processing technology. Their waveguiding performances were tested by the end-face coupling technique, which results in the waveguides having excellent transmission performances at the wavelengths of 633 and 1 550 nm. The guidance is valid only for TM polarization with the single-polarized nature. By calculating the transmission loss of the waveguide, it is concluded that the 30 μm diameter waveguide has the best transmission performance at 633 and 1 550 nm wavelengths. The experimental results are proved to be reasonable by theoretical calculations using Rsoft software. The results of this study provide an important reference for the design and performance optimization of optical waveguides, and have certain experimental and theoretical value. [ABSTRACT FROM AUTHOR]

Lithium niobate crystal has many advantages such as large electro-optical, piezoelectric and non-linear optical coefficients, wide optical transparency range, compatibility with speed matching, phase matching and dispersion engineering, long-term stability and low-cost preparation of optical-grade wafers. As an important platform for constructing optoelectronic devices such as electro-optic modulators, optical frequency combs and optical waveguides, lithium niobate holds grant promise in the fields of light generation, light transmission and light modulation in the field of information and communication. Lithium niobate is also well known as the "silicon of photonics" and has huge integration potential in both academia and industry. However, due to the insulator and weak optical absorption properties of lithium niobate, integrated application fields based on lithium niobate platforms also face the problems of low photo-to-electric conversion efficiency and thus arouse difficult in photodetection. Light demodulation and light extraction in all-optical communications require high-performance detectors, therefore, the development of photodetectors based on lithium niobate has great scientific significance and application value. Starting from the basic structural characteristics of lithium niobate, this article introduces in detail the excellent physical properties and photo-to-electric conversion mechanism of lithium niobate, reviews some recent research results of domestic and foreign scholars, and focuses on the optical waveguide integrated photodetectors and the heterogeneous type photodetectors based on lithium niobate crystals, the advantages and development potential of different routes are discussed and compared, and prospects for this field are proposed. [ABSTRACT FROM AUTHOR]

Photonic sensors utilize light–matter interaction to detect physical parameters accurately and efficiently. They exploit the interaction between photons and matter, with light propagating through an optical waveguide, creating an evanescent field beyond its surface. This field interacts with the surrounding medium, enabling the sensitive detection of changes in the refractive index or nearby substances. By modulating light properties like intensity, wavelength, or phase, these sensors detect target substances or environmental changes. Advancements in this technology enhance sensitivity, selectivity, and miniaturization, making photonic sensors invaluable across industries. Their ability to facilitate sensitive, non-intrusive, and remote monitoring fosters the development of smart, connected systems. This overview delves into the material platforms and waveguide structures crucial for developing highly sensitive photonic devices tailored for gas and biosensing applications. It is emphasized that both the material platform and waveguide geometry significantly impact the sensitivity of these devices. For instance, utilizing a slot waveguide geometry on silicon-on-insulator substrates not only enhances sensitivity but also reduces the device's footprint. This configuration proves particularly promising for applications in biosensing and gas sensing due to its superior performance characteristics. [ABSTRACT FROM AUTHOR]

Ultrafast lasers, characterized by femtosecond and picosecond pulse durations, have revolutionized material processing due to their high energy density and minimal thermal diffusion, and have played a transformative role in precision manufacturing. This review first traces the progression from early ruby lasers to modern titanium–sapphire lasers, highlighting breakthroughs like Kerr-lens mode-locking and chirped pulse amplification. It also examines the interaction mechanisms between ultrafast pulses and various materials, including metals, dielectrics, and semiconductors. Applications of ultrafast lasers in microstructure processing techniques are detailed, such as drilling, cutting, surface ablation, and nano welding, demonstrating the versatility and precision of the technology. Additionally, it covers femtosecond laser direct writing for optical waveguides and the significant advancements in imaging and precision measurement. This review concludes by discussing potential future advancements and industrial applications of ultrafast lasers.

Optical resonators are particularly suitable for anaemia state detection due to small sample size, real-time detection and low power consumption. However, the quality factor and sensitivity of resonant cavity sensors are mutually constrained, so the single objective optimization algorithms proposed so far can only achieve a single optimization of sensitivity or quality factor, which limits chip performance. This article presents a multi-objective optimization design of the runway ring resonant cavity sensor based on the BP-NSGA II algorithm, which has achieved good performance improvement. The simultaneous incorporation of quality factor and sensitivity provides access to key structural design parameters to overcome the limitations of sensitivity and quality factor constraints on each other, thereby improving sensor performance. The results show that the optimized structure has a sensitivity of 439 nm/RIU, a quality factor of 938, a relative error of 1.37% and 3.9% for the sensitivity and quality factor, respectively, a linearity of 0.00004636% for the sensitivity, and a training time of 3 min. The method has the advantages of small errors and short learning time. A new optimization method is provided for the design of the resonant cavity of a runway ring. [ABSTRACT FROM AUTHOR]

The luminescence color of molecule‐based photoactive materials is the key to the applications in lighting and optical communication. Realizing continuous regulation of emission color in molecular systems is highly desirable but still remains a challenge due to the individual emission band of purely organic molecules. Herein, a novel alloy strategy based on molecular co‐crystals is reported. By adjusting the molar ratio of pyrene (Py) and fluorathene (Flu), three types of molecular co‐crystal alloys (MCAs) assemblies are prepared involving Py‐Flu‐OFN‐x%, Py‐Flu‐TFP‐x%, Py‐Flu‐TCNB‐x%. Multiple energy level structure and Förster resonance energy transfer (FRET) process endow materials with tunable full‐spectra emission color in visible region. Impressively, these MCAs and co‐crystals can be successfully applied to low optical loss waveguide and optical logic gate by virtue of all‐color luminescence from blue across green to red, together with smooth surface of one‐dimensional microrods, which show promising applications as continuous light emitters for advance photonics applications. [ABSTRACT FROM AUTHOR]

Optical waveguides create interesting opportunities in the area of soft sensing and electronic skins due to their potential for high flexibility, quick response time, and compactness. The loss or change of light intensities inside a waveguide can be measured and converted into useful sensing feedback such as strain or shape sensing. Compared to other approaches such as those based on microelectromechanical system modules or flexible conductors, the entire sensor state can be characterized by fewer sensing nodes and less encumbering wiring, allowing greater scalability. Herein, simple light‐emitting diodes (LEDs) and photodetectors (PDs) combined with an intelligent shape decoding framework are utilized to enable 3D shape sensing of a self‐contained flexible substrate. Multiphysics finite element analysis is leveraged to optimize the PDs/LEDs layout and enrich ground‐truth data from sparse to dense points for model training. The mapping from light intensities to overall sensor shape is achieved with an autoregression‐based model that considers temporal continuity and spatial locality. The sensing framework is evaluated on an A5‐sized flexible sensor prototype and a fish‐shaped prototype, where sensing accuracy (RMSE = 0.27 mm) and repeatability (Δ light intensity <0.31% over 1000 cycles) are tested underwater. [ABSTRACT FROM AUTHOR]

In this work, the ridge waveguide was formed by the femtosecond laser ablation with a central wavelength of 0.808 μm and a speed of 50 μm/s on the planar Nd3+‐doped fluorophosphate glass waveguide that was fabricated by the C3+ ion implantation with an energy of 6.0 MeV and a fluence of 1.0×1012 C3+s/mm2. The mechanism of the ion‐implanted waveguide was discussed by the Stopping and Range of Ions in Matter 2013. The cross‐section morphology of the ridge waveguide was captured by an optical microscope. Its mode characteristics were analyzed by the end‐face coupling method. The ridge Nd3+‐doped fluorophosphate glass waveguides have potential as fundamental structures for many optoelectronic devices including waveguide amplifiers and lasers. [ABSTRACT FROM AUTHOR]

Optical waveguides are crucial in the development of integrated optical circuits. This study examines their formation in dielectric materials using ultrashort pulse laser direct writing. Emphasizing the significance of the processing parameters for writing low-loss waveguides, we explored the underlying mechanisms through in situ observations of internal modifications and a detailed analysis of electron density and refractive index changes. Employing a combination of pump-probe imaging and Mach-Zehnder interferometry, we reveal the dynamics of laser-induced modifications in quartz, highlighting the influence of spatial overlap and irradiation spacing. Our research offers insights into the micro-level phenomena that affect the overall waveguide performance, thereby providing enhanced fabrication methods. [ABSTRACT FROM AUTHOR]

This work explicitly demonstrates a semi-analytical effective index approximation (EIA) approach for the description of the propagation properties of rib and ridge waveguides. By using the example of waveguides realized on a low-cost silica-titania (SiO2:TiO2) technological platform, we present that EIA may be successfully applied for the approximate determination of modal effective indices and single mode propagation conditions. All obtained results have been confirmed to be convergent with the finite element method (FEM) simulations at low relative error. Due to the tremendously fast execution time of EIA simulations in comparison with the FEM solver, we believe that the presented approach may be applied in a preliminary step of designing functional blocks in new and existing photonic integrated circuit technologies, which often require complex and multi-parameter calculations. [ABSTRACT FROM AUTHOR]

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In this work, a novel plasmonic structure is presented for guiding surface plasmon polaritons, which can be used as a fundamental waveguide in various plasmonic devices. The placement of a graphene nanoribbon between two dielectric layers results in a high concentration of plasmonic waves at the graphene-dielectric interface. Excellent light confinement at the center of the waveguide prevents energy leakage to the lateral regions. As a result, a loss of 0.029 dB/µm and a coupling length of 187.9 µm are achieved, which are better compared to results obtained in other waveguides. The figure-of-merit of 1363.4 for a wavelength of 9.4 µm also indicates that the proposed waveguide has a suitable performance in controlling and guiding surface plasmons. Furthermore, the size of 420 nm2 demonstrates that the designed waveguide is suitable for integration in photonic circuits and can be employed in different devices. The low loss, long coupling length, and compact size of the designed waveguide highlight its excellent performance in guiding surface plasmon polaritons. [ABSTRACT FROM AUTHOR]

We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters of edge-emitting lasers, based on a separate confinement double heterostructure. It is shown that there are three degrees of influence, according to the etching depth: modification of the waveguide properties only, a decrease in efficiency without changing the threshold current, and a simultaneous deterioration in the threshold current and efficiency with significant modification of the optical characteristics of the laser. [ABSTRACT FROM AUTHOR]

The temperature characteristics of ring lasers with a diameter of 480 μm of an original design with an active region based on 10 layers of InAs/InGaAs/GaAs quantum dots are studied. The lasers demonstrated a low threshold current density (200 A/cm2 at 20°C), the characteristic temperature of the threshold current in the range of 20–100°C was 68 K, the maximum lasing temperature was as high as 130°C. These values are only slightly inferior to the parameters of the edge-emitting lasers fabricated from the same epitaxial wafer. [ABSTRACT FROM AUTHOR]

In this study, single-mode conditions and bending losses of optical waveguides based on Ge33As12Se55 chalcogenide glass, commercially known as IG2, for astrophotonic devices in the mid-infrared spectral range are numerically analyzed. The scalar finite-element method was used to analyze singlemode conditions. For the bending-loss analysis, equivalent straight waveguides of bent waveguides were analyzed using the two-dimensional finite-difference beam-propagation method. The results revealed design rules for astrophotonic optical integrated circuits in the mid-infrared spectral range. [ABSTRACT FROM AUTHOR]

Highly integrated and stable devices are appealing in optical communication and sensing. This appeal arises from the presence of high refractive index contrast and high-quality waveguides. In this study, we improved the vapor proton exchange (VPE) process, enabling large-scale waveguide fabrication and addressing the issue of liquid exchange during cooling. Additionally, we have prepared and characterized planar waveguides on X-cut lithium niobate (LN) crystals. The exchanged samples exhibit α and k1 phases, refractive index contrasts as high as 0.082, and exceptional refractive index uniformity. Furthermore, we utilized the same process to fabricate channel waveguides and Y-branch waveguides. We achieved low propagation losses in channel waveguides, accompanied by small mode sizes, and low-loss Y-branch waveguides with a highly uniform beam splitting ratio. All waveguides exhibited consistent performance across multiple preparations and tests, remaining free from aging effects for three months. Our results underscore the promising potential of VPE for creating Y-branch splitters and modulators in LN crystals. [ABSTRACT FROM AUTHOR]

Flexible molecular crystal waveguides based on elastic molecular crystals (EMCs) are essential in flexible and compact optical materials. An increased loss coefficient α due to self‐absorption is often a problem in optical waveguides (OWGs) of fluorescent chemical materials waveguiding photons in active mode. Herein, the development of anthracene‐based elastic mixed molecular crystals (EMMCs) is reported for Förster Resonance Energy Transfer (FRET)‐assisted OWG. To yield a FRET crystal system based on elastic molecular crystals, 1%–5% acceptor doping for fluorescent molecular crystals of 9,10‐dibromoanthracene 1 was successful by selecting the same regioisomer having electron‐withdrawing group, 9,10‐diformylanthracene 2, as a dopant. In addition to conversion to the mixed system, there is a difference in the elastic modulus and hardness in EMC C1 and EMMC C2@1. However, the elastic behaviour was also shown in a few percent doping of the acceptor. The α value of this EMMC, composed of 1 including 1% of 2 (0.0077 dB/μm), is much lower than that of EMC composed of 1 (0.1258 dB/μm) because of reducing self‐absorption in the FRET system. An efficient and flexible OWG was successfully developed by selecting an appropriate acceptor molecule and its low doping rate for mixed crystal construction. This method is a practical approach in various functional and flexible crystal systems. [ABSTRACT FROM AUTHOR]

Abstract Ensuring information security has emerged as a paramount concern in contemporary human society. Substantial advancements in this regard can be achieved by leveraging photonic signals as the primary information carriers, utilizing photonic logical gates capable of wavelength tunability across various time and spatial domains. However, the challenge remains in the rational design of materials possessing space‐time‐color multiple‐resolution capabilities. In this work, a facile approach is proposed for crafting metal‐organic halides (MOHs) that offer space‐time‐color resolution. These MOHs integrate time‐resolved room temperature phosphorescence and color‐resolved excitation wavelength dependencies with both space‐resolved ex situ optical waveguides and in situ heterojunctions. Capitalizing on these multifaceted properties, MOHs‐based two‐dimensional (2D) optical waveguides and heterojunctions exhibit the ability to tune full‐color emissions across the spectra from blue to red, operating within different spatial and temporal scales. Therefore, this work introduces an effective methodology for engineering space‐time‐color resolved MOH microstructures, holding significant promise for the development of high‐density photonic logical devices.

Abstract The development of high‐performance organic blue light‐emitting emitters is in urgent to act as an excitation source to contribute the white light generation. On the other hand, the investigation on optical waveguides have been received increasing attentions because they can manipulate the light propagation accurately in the microscale to boost the optoelectronic and energy conversion applications. In this work, we facilely prepared a deep‐blue aggregation‐induced emission (AIE) dye, namely TPP‐4OMe, which shows high luminescent efficiency, narrow emission band and good stability in the aggregate state. TPP‐4OMe can be fabricated as deep‐blue AIE microfibers readily with definite morphology and composition. Based on the AIE microfibers, the active waveguide to transmit deep‐blue emission signals can be achieved with a very low optical loss coefficient (α) of 6.7 × 10−3 dB μm−1. Meanwhile, the full‐visible broadband low‐loss passive waveguide can be well performed with these AIE microfibers, which has never been observed in the pure organic crystals. More interestingly, the excellent properties of AIE microfibers enable them to act as a wave‐guiding excitation source, resulting in a distinct and pure white light emission. The present work not only provides excellent blue light‐emitting materials but also bridges the waveguide to realize the efficient white light emission to accelerate the practical applications.

This study introduces the design of a nonlinear frequency-modulated continuous wave (FMCW) laser ranging system. In contrast to the commonly used triangular wave linear modulation, this study utilizes sinusoidal wave modulation. The frequency information of the original sinusoidal frequency-modulated signal is extracted using an on-chip interferometer based on SiON waveguides and IQ demodulation technology. After fitting the measured interference signal at equal frequency intervals, the corresponding distance information is derived using the fast Fourier transform (FFT). The principles underlying this method are thoroughly analyzed and derived, with its accuracy confirmed through experimental validation.

Visible Light Communication (VLC) has become an effective underwater communication technology due to its advantages such as fast transmission speed and strong confidentiality. When light propagates underwater, it is prone to scattering, resulting in a decrease in the energy of light propagation with the increase of transmission distance. Therefore, improving the responsiveness of the receiving end is the key technology to achieve underwater VLC. This article first designs a new holographic waveguide focusing system for the front end of the detector, which can effectively improve the signal-to-noise ratio of underwater detectors. Then, we construct a low-cost antimony sulfide thin film detector with weak light detection capability. Based on the built VLC system, the experimental results show that the dark current of the receiver detector is only 10-7 A/cm2, with a 3 dB bandwidth of 220 kHz, a response of 0.2 A/W, and an external quantum efficiency of over 70% in the blue green light band. Therefore, the new antimony sulfide thin film detector combined with a holographic waveguide focusing system can achieve weak light detection of visible light, making it a very effective underwater visible light receiving system.

Abstract This paper presents a study of a segmented waveguide where the layers are distributed following the Fibonacci sequence and aims to diminish the scattering losses usually caused by imperfections in the core boundaries of the waveguide. This phenomenon normally happens in structures which present a high contrast between the refractive index of the core and the refractive index of the clad. The analyses were obtained through observations of wave fields that propagates along the waveguide, how the effective refractive index (neff) varies along the z-direction and the study of its normalized power. The simulation of this photonic component was accomplished with the help of the Vectorial Beam Propagation Method (VBPM).

Optical waveguides create interesting opportunities in the area of soft sensing and electronic skins due to their potential for high flexibility, quick response time, and compactness. The loss or change of light intensities inside a waveguide can be measured and converted into useful sensing feedback such as strain or shape sensing. Compared to other approaches such as those based on microelectromechanical system modules or flexible conductors, the entire sensor state can be characterized by fewer sensing nodes and less encumbering wiring, allowing greater scalability. Herein, simple light‐emitting diodes (LEDs) and photodetectors (PDs) combined with an intelligent shape decoding framework are utilized to enable 3D shape sensing of a self‐contained flexible substrate. Multiphysics finite element analysis is leveraged to optimize the PDs/LEDs layout and enrich ground‐truth data from sparse to dense points for model training. The mapping from light intensities to overall sensor shape is achieved with an autoregression‐based model that considers temporal continuity and spatial locality. The sensing framework is evaluated on an A5‐sized flexible sensor prototype and a fish‐shaped prototype, where sensing accuracy (RMSE = 0.27 mm) and repeatability (Δ light intensity

Abstract The luminescence color of molecule‐based photoactive materials is the key to the applications in lighting and optical communication. Realizing continuous regulation of emission color in molecular systems is highly desirable but still remains a challenge due to the individual emission band of purely organic molecules. Herein, a novel alloy strategy based on molecular co‐crystals is reported. By adjusting the molar ratio of pyrene (Py) and fluorathene (Flu), three types of molecular co‐crystal alloys (MCAs) assemblies are prepared involving Py‐Flu‐OFN‐x%, Py‐Flu‐TFP‐x%, Py‐Flu‐TCNB‐x%. Multiple energy level structure and Förster resonance energy transfer (FRET) process endow materials with tunable full‐spectra emission color in visible region. Impressively, these MCAs and co‐crystals can be successfully applied to low optical loss waveguide and optical logic gate by virtue of all‐color luminescence from blue across green to red, together with smooth surface of one‐dimensional microrods, which show promising applications as continuous light emitters for advance photonics applications.