This PDF file contains the front matter associated with SPIE Proceedings Volume 12764, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

We proposed an integrated semiconductor laser scheme that combines an ultra-high Q silicon nitride microresonator with a DBR semiconductor laser, resulting in a tunable ultra-narrow linewidth laser. The experiment achieves tuning within the wavelength range of 1554.2-1557.15nm (about 370GHz), being almost ten times larger than that of reported DFB scheme. Moreover, the sidemode suppression ratio is low to 52dB with a ultra-narrow linewidth about 6.6kHz. It needs the joint adjustment of DBR operating current, coupling of the high-Q silicon nitride external cavity. These results can be applied in fields such as dense wavelength division multiplexing systems and integration LiDAR System.

Based on a high power InGAsP distributed feedback (DFB) semiconductor laser coupling with an ultra-high-Q silicon nitride microring, we proposed a hybrid integration semiconductor laser scheme for realizing high power and narrow linewidth. For such a scheme, the high power DFB laser serves as the light source, whose output is efficiently coupled into the input waveguide port of ultra-high-Q silicon nitride microring through a silicon lens. Under the optical feedback provided by the Rayleigh scattering in the inhomogeneity silicon nitride microring, the laser may be driven into the self-injected locking state, under which the lasing linewidth can be obviously narrowed. The experimental results demonstrate that, adopting such a hybrid integration scheme, the lasing linewidth can be narrowed to 10 kHz and meanwhile the output power is maintained at the level of 20 mW. The hybrid integration semiconductor lasers have application prospects in some fields simultaneously requiring high coherence and high power, such as LiDAR and long-distance coherence communication.

Silicon nitride photonic integrated circuits with ultra-low loss are widely used in applications such as telecommunications and optical sensing. However, the radiation loss increases rapidly as the radius is reduced, resulting in large-sized silicon nitride photonic integrated circuits. The weak thermo-optical effect limits the high-efficiency, low-power consumption applications. In this paper, a stepped index waveguide structure is studied to reduce the bending loss by enhancing the mode confinement. A bend with a radius of 30μm is designed using Ansys MODE. Polymer with a high thermo-optic coefficient is used as the cladding of the silicon nitride waveguide to improve the tuning performance of the phase shifter. The grooves around the waveguide also acts as an adiabatic trench to increase the efficiency of the thermal electrode. A π phase shift under thermal tuned power of 7.5mW is achieved with a 300μm long silicon nitride waveguide. Finally, a cascaded silicon nitride micro-ring resonator with radius of 50μm is designed to achieve an efficient filter with a wide tuning range of 116nm. This scheme provides a novel approach for high-density, wide-tunable and miniaturized devices in silicon nitride photonic integrated circuits.

Although the polarization converter utilizing silicon photonics technology has been reported several years ago, either the performance (conversion efficiency and operation window) or the manufacture is always limited by the cross-polarization coupling theory. We discovered that an asymmetric nanowire waveguide changing along the wave propagation direction produced a gradient effective mode index. A TE-to-TM polarization converter consisted of an asymmetric nanowire waveguide and a uniform nanowire waveguide constructed on the SOI platform was demonstrated. Gradient effective mode index effect and mode coupling theory promoted an ultra-high polarization conversion efficiency of 99.997% and broad wavelength operation window of 100 nm. Compact configuration presents high integration density, which benefits the on-chip mode multiplexing technology. Simple structure with moderate critical dimension facilitates the fabrication fast and cheap.

Nonvolatile light-field manipulation via electrically-driven phase transition of chalcogenide phase change materials (PCMs) is regarded as one of the most powerful solutions to low-power-consumption and compact integrated reconfigurable photonics. However, before the breakthrough in large-scale integration approaches linked to wafer foundries, phase-change non-volatile reconfigurable photonics could hardly see their widespread practical applications. Here we demonstrate nonvolatile photonic devices fabricated by back-end-of-line (BOEL) integration of PCMs into the commercial silicon photonics platform. A narrow trench etched into the BOEL dielectric layer exposed the waveguide core and allowed for the direct deposition of various PCM films on the waveguide in the functional areas. Fine-tuning the nonvolatile phase transition of Sb₂Se₃ via a PIN microheater was verified by realizing the post-fabrication trimming of silicon photonic devices. Our work highlights a reliable platform for large-scale PCM-integrated photonics and validates its precise nonvolatile reconfigurability.

Graphene is considered a suitable atomically thick layer on photocathodes, and the photoemission performance of the graphene-covered photocathodes can be enhanced through Cs/O activation. To investigate the effects of the substrate materials beneath the graphene layer on Cs/O deposition and photoemission performance. We compare the activation processes and photoemission performances of few-layer graphene supported by nickel and copper to investigate the effects of the substrate materials beneath the graphene layer on Cs/O deposition and photoemission performance. By Cs/O activation, the nickel-supported few-layer graphene can possess a higher response at 405 nm, while the copper-supported cathode can acquire a wider spectral response and better stability. After degradation, we discover that the samples supported by nickel and copper can act differently through the additional Cs/O deposition processes, while the surface barrier heights of both samples are further decreased.

Rare-earth-ion-doped materials provide many opportunities for on-chip amplifiers and light sources, which are important to silicon photonics. Here, we report an erbium-doped waveguide amplifier using atomic layer deposition. Method optimization yields erbium-doped Al2O3 films with excellent optical properties, which are showcased by the high-performance photoresist-erbium-doped Al2O3 hybrid amplifiers. We demonstrate signal enhancements (SE) of 30.4 dB and 16 dB at 1531.6 nm and 1550 nm in a 3.55-cm-long amplifier, respectively, corresponding to net gains of 8.4 dB and 5 dB. Furthermore, SE and gain increase with waveguide length under sufficient pumping, suggesting the potential for achieving greater gains for longer erbium-doped waveguide amplifiers. This work represents an important step towards high-gain rare-earth-ion-doped amplifiers and the integration of active devices on silicon platforms.

A single-mode Nd-doped solid-core anti-resonant fiber with core diameter of 27 μm was designed for high-power 900 nm laser generation. The simulated result of the designed fiber shows that in the 870~900 nm band, the fundamental mode loss is less than 0.1 dB/m while all the higher-order mode losses are higher than 10 dB/m. More importantly, the loss of all the modes in the 1060 nm band is greater than 100 dB/m, which can guarantee high-power laser generation at 900 nm while suppressing the parasitic lasing around 1060 nm. Based on the designed Nd-doped fiber, a 900 nm fiber amplifier was simulated, which reveals that the amplified spontaneous emission around 1060 nm can be effectively suppressed and a laser slope efficiency up to 54% can be obtained from 0.5 m gain fiber with 100 mW of laser seed.

Fiber scrambling is important in high-precision calibration systems for radial velocity measurement for searching for exoplanets. As for laser frequency combs, the modal noise of significant laser speckles can occur due to the strong coherence of the light source, which can be effectively suppressed by vibrating the fiber. However, the fibers used for scientific target detection are coupled with polychromatic light from the celestial body. This study focuses on the fiber mode noise and length dependency under white light conditions, and proposes a new fiber scrambling method of combining different types of fiber to achieve high scrambling gain. The results show that the fiber mode noise increases with decreasing length, and that there is also significant mode noise when the fiber is less than 2m, resulting in a speckle-like pattern as the modal pattern in the near field. The combination of non-circular fibers and graded index fibers can effectively reduce mode noise and improve the scrambling gain.

In this work, a novel microwave photonic approach is applied to generate an arbitrary chirp microwave waveform in the Ku band that possesses a high chirp rate. Chirp microwave signals can be produced in a variety of ways, the most common of which is the shaping of the temporal pulse and the mapping of the wavelength to the time. The usage of Kuband frequencies is widespread in modern radar applications, such as high-resolution mapping and satellite altimetry. The range-Doppler resolution of a radar system can be enhanced by improving its chirp rate, time-bandwidth product, and center frequency. The proposed approach in this work is based on the direct modulated Laser source and polarization controller. The theoretical and simulation analysis has been done to generate a dual linear chirp microwave signal in the Ku band with a center frequency of 12 GHz.

High precision alignment between the fiber core in the focal plane and the image of the target star is of great significance for the observation of multi-target telescopes. In this work, we propose and demonstrate a Special-shaped Micro-lens Aimer for Real-time Targeting, namely SMART, combining a special-shaped microlens and a fiber bundle to realize online alignment and improve the coupling efficiency of fibers. The platform in the center of the microlens transmits the starlight to the science fiber of the fiber bundle without changes in focal ratio. Six side micro-lenses couple leakage light to six feedback fibers and return misalignment signals. The structural parameters of SMART are well designed. Fresnel diffraction theory is applied to build a model for simulating the performance of SMART. In the SMART measurement, a pinhole with a diameter of 200 μm is used to imitate the effect of atmospheric turbulence during astronomical observations. Experimental results indicate that when the image spot is offset relative to the science fiber, the misaligned direction and displacement distance are identified by the signal of feedback fibers in SMART with a resolution of 0.02 mm and a detection range of 0.08 mm to 0.26 mm.

We can achieve a high frequency with a low-phase-noise microwave photonics signal with the help of an optoelectronic oscillator (OEO). In this paper, we propose an OEO based on an external modulator and a dispersive component that provides frequency selection properties similar to those of the photonic filter, i.e. π phase-shifted fiber Bragg grating (π PS-FBG), which has a fixed center frequency of 1550nm. By changing the wavelength of an optical carrier signal, we can tune the oscillating frequency of the OEO. The π PS-FBG reflected signal was passed through parallelly connected single-mode fibers of 0.1 Km, 0.2 Km, and 0.4 Km length. An extra delay in the loop is provided for locking the oscillating frequency. we use π PS-FBG filters designed for the wavelengths 1550 nm to 1555 nm and the corresponding frequency of oscillation was observed between 4.63 GHz and 40.17 GHz. We make observations of the oscillating frequency. With the help of simulated results, the overall model has been theoretically analyzed and verified.

In this paper, we present the operation of an optoelectronic oscillator. We look at the evaluation of the uncertainty associated with the measurement of the phase noise of the signal emitted by this oscillator. Uncertainty on the phase noise measured for a low phase noise compact optical delay line optoelectronic oscillator is evaluated as ±1.5 dB at 2 σ.

This study provides a novel two-dimensional beam steering mechanism that takes advantage of wireless optical power systems utilizing diverging angular dispersion laser beams and the resonant beam charging technique. The system exhibits significant improvements compared to conventional systems that utilize pencil beams. These enhancements include reducing scanning time, capable of mitigating inherent errors, and increasing the ability to charge resonant cavities continuously. Specifically, our system exhibits scanning times that are 1.2 times faster than traditional systems. This opens the pathway for practical deployments of beam steering for RBC-based WOPT, enabling real-time charging and communication.

The ability to manipulate light propagation is crucial for the development of optical communication and information processing systems. Photonic integrated circuits have gained significant attention due to their ability to integrate a large volume of components and operate at high speeds, making them ideal for handling the increasing data capacity and rate. In this study, we proposed and experimentally demonstrated a novel method for beam steering using waveguide arrays with specific distributed spacing profiles. By analyzing the diffraction and coherence properties, we discovered that a single waveguide array can perform imaging and phase transformation functions, which are typically achieved using optical lenses. To further enhance this capability, we fabricated corresponding devices on a silicon nitride waveguide platform and investigated the light propagation process through the arrayed waveguide. We successfully achieved various forms of beam steering, including focusing, expansion, and collimation. This beam control method holds great potential for on-chip optical routing, ranging, sensing, and other applications. It offers high integration density and scalability, making it a promising solution for the development of advanced optical systems.

Optical array antennas have diverse applications in optical communication, remote sensing, imaging, and astronomy, supporting a broad range of optical and photonics-based technologies. Traditional square phased array antennas require a half-wavelength emitter spacing to prevent secondary orders of emission (aliasing). However, achieving such small distances in optics is impractical. To break this limitation irregularly-placed arrays has been proposed. This study focuses on the alias-free spiral array, which allows for high level of sidelobe suppression. Using standard Huygens–Fresnel principle approach to calculate the emission pattern, we identify key parameters of the spiral and consider their influence on the result. We perform multi-parametric optimisation of the spiral array for maximum suppression of sidelobes, enhancing its performance by dB compared to previously suggested bio-inspired design. This research provides insights into overcoming aliasing challenges and improving the efficiency of optical array antennas.

This article conducts an experimental investigation into the impact of laser polarization and angle of incidence on the efficiency of a liquid crystal enabled 0-180° phase shifting delay line operating at the X band. According to measurement results, the polarization of the laser beam with regard to the rubbing direction and the liquid crystal filling direction has a significant impact on the tuning efficacy of the delay line. The possible phase shift is increased when the laser beam is polarized parallel to both the liquid crystal filling direction and the rubbing direction. Furthermore, the effectiveness of the delay line's phase shifting is non-linearly influenced by the angle of incidence, as evidenced by another two experiments that were carried out with the laser source rotated at the same and diverse planes relative to the fixed rubbing alignment direction, respectively.

Accurate time-domain simulation is crucial for designing large and complex photonic integrated circuits (PICs). Passive devices and circuits, such as Mach-Zehnder interferometers and all kinds of wavelength filters, play important roles in PICs, with their input and output characteristics typically described using S-parameters. However, their practical application in the time domain is limited by the fact that they are usually band-limited. Applying the inverse fast Fourier transform (IFFT) directly to these band-limited S-parameters can result in impulse responses that violate causality significantly. To address this issue, this paper proposes a novel method for extrapolating S-parameters of photonic circuits in order to obtain causal and accurate impulse responses.

According to the requirement of aircraft test mission, a set of radiant heat simulation system which can be used in complex extreme environment is developed in this paper. The system is mainly composed of optical subsystem, mechanical structure, cooling subsystem and control subsystem. The design process of this system mainly includes optical system design, mechanical structure design, cooling system design, control system design and environmental adaptability design. The radiant heat simulation system needs to ensure the normal operation under the extreme environment of low pressure (5kPa), high humidity (90%RH), high temperature (75°C) and low temperature (-20°C). In order to solve this difficulty, the system developed a special light source protection cabin. The protection chamber can provide normal temperature, normal pressure and low humidity working environment for the light source. With the help of cooling system and control system, the environment adaptability of radiant heat simulation system is ensured effectively. After the development of the radiant heat simulation system, six indexes including irradiance, spectrum, illumination area, irradiation uniformity, irradiation stability and environmental adaptability were evaluated according to the test standards. At present, the radiant heat simulation system has been involved in part of the aircraft test, the effect has been recognized by the test department.

Due to the wave nature of light and the influence of optical material properties, the design and performance of photonic circuits can be relatively complex. While computer-aided software tools such as CAD can improve the efficiency of photonic circuit development, they still face challenges in handling large-scale photonic integrated circuit (PIC) designs. In this paper, we develop a photonics design automation tool, called GT Photonics, which provides a flexible development environment capable of handling large-scale PIC designs. The GT Photonics platform integrates multiple high-performance photonic devices, including passive and active components, and allows users to freely develop and adjust the parameters of individual photonic devices. To enhance development efficiency, the platform offers various design methods, modular development, parameter unit reuse, customizability, and intelligent routing capabilities. These features streamline the development of complex photonic integrated circuits. To facilitate development, the platform defines a netlist view to record photonic device information and employs visual design methods for circuit visualization. Once the design is completed, the photonic circuit can be exported as a Graphic Data System version 2 (GDSII) file for performance simulation and validation. This article presents a case study involving the design of an optical phased array (OPA) using the GT Photonics platform. The case study encompasses the design process, design outcomes, and various design details. Photonic design automation holds significant importance for engineering and research endeavors.

With the development of Internet of Things (IoT) technology, there is an increasing demand for integrated optoelectronic systems. Multiple quantum well (MQW) diodes can transmit and receive information through visible light, serving as both light-emitting diodes (LEDs) and photodetectors. Furthermore, the overlap of emission-detection spectra in III-nitride MQW diodes provides an interesting capability of detecting and modulating their own emitted light. In this study, we have experimentally demonstrated the coexistence of emission-detection in III-nitride MQW diodes and established an optical-based wireless audio communication system. When the bias voltage is greater than the turn-on voltage and the device is simultaneously illuminated, III-nitride MQW diodes can achieve both light emission and detection. This work paves the way for developing versatile III-nitride MQW diodes for device-to-device data communication in smart displays.

Silicon-organic hybrid (SOH) modulators are promising as they have large bandwidth, high modulation efficiency and low optical loss. In this paper, we present the optical and electrical design and simulation of a high-speed travelling wave SOH modulator with multiple interplay parameters. We also implement the electro-optical co-optimization to delve into the influence of the key design parameters and propose the design guideline. The results demonstrate a modulator with 3 dB bandwidth of 72 GHz, modulation efficiency of 1.26 Vmm and optical loss less than 1 dB.

The management of polarization state is crucial for silicon photonics, however, it is often compromised by weak light-matter interactions, leading to the need for extending footprints of on-chip devices and huge power cost. In this paper, we propose a tunable silicon photonic polarizer designed to separate and manipulate polarization states based on selective silicon asymmetric directional couplers (ADCs) assisted with phase change material (PCM)[4]. The proposed polarizer includes a polarized beam splitter, a TE mode selective ADC assisted with PCM, a TM mode selective ADC assisted with PCM and a polarized light combiner. By tuning the GST of the TE/TM light selective ADC into crystalline state, phase matching occurs in the directional coupler between the hybrid waveguide and the bus waveguide, then the TE/TM modes can be efficiently excluded from the polarizer. On the other hand, by tuning the GST of the TE/TM light selective ADC into amorphous state, there is a phase mismatch between the hybrid waveguide and the bus waveguide, then the TE/TM light can pass through the bus waveguide and output from the polarized beam combiner. Simulation results indicate that this selective silicon photonic polarizer has a high extinction ratio over 37 dB for the TM mode and over 31 dB for the TE mode, with a minimal insertion loss of 1.2 dB for the input light.

O-band edge couplers exhibit significant promise in silicon-based optoelectronic chips, particularly for applications within data centers. However, the task of designing a low-loss O-band silicon edge coupler with a wider minimum width, capable of interfacing with standard single mode fibers (SMF), presents greater challenges compared to its C-band counterpart. In this work, we propose, design and simulate a three-etching silicon edge coupler devoid of a cantilever structure, leveraging a 130 nm CMOS process. By incorporating a silicon oxide cladding with a refractive index 0.007 greater than that of the buried oxide, we successfully mitigate silicon leakage losses, particularly for the TM mode. Furthermore, we introduce a novel taper shape design methodology rooted in mode analysis. Within this designed taper shape, the effective refractive index or area of the supported mode experiences an equal rate of change as the taper width increases. Thanks to these innovative designs, our simulations reveal a minimum loss of 0.82/1.68 dB and a loss range of 0.69/0.38 dB for TE/TM modes in the O band when interfacing with standard SMF. Most notably, our edge coupler, featuring the designed taper shape, demonstrates an average coupling loss improvement of 1.23/0.44 dB for TE/TM modes compared to the parabolic counterpart. This work introduces a novel taper shape design approach for compact and low-loss edge couplers, offering a practical solution for achieving low-loss SMF-chip coupling within the O band.

We demonstrate a high-efficiency silicon nitride grating coupler for perfectly vertical coupling. The directionality of the diffraction process is improved with the help of the bottom mirror and Bragg reflectors introduced in the design, leading to the minimal coupling loss of -0.52 dB at 1315.6 nm.

In this paper, we propose an all optical JK flip-flop system consisting of three vertical-cavity surface-emitting lasers with embedded saturable absorber (VCSEL-SAs) is proposed and numerically simulated. Also, the effects of injection intensity, delay and noise on the JK flip-flop are numerically analyzed. The results show that, based on the spiking dynamics of excited VCSEL-SA, the proposed all-optical JK flip-flop model can perform all the fundamental functions of conventional JK flip-flop under suitable bias current, injection intensity and perturbation delay between two trigger signals. Moreover, the noise has a little effect on the performance of JK flip-flop, but the proposed system has good robustness to the noise. The results provide a feasibility for the application of VCSEL-SA devices in the future ultrafast neuromorphic computing systems.

To meet the requirements of high dynamic range applications of LiDAR, this paper designs the silicon avalanche photodetector (Si APD) with large linear gain, which can reduce the difficulty of subsequent APD circuits and improve the accuracy of laser ranging. In this paper, a planar n+-p-π-p+ avalanche photodetector (APD) is formed by ion implantation and annealing process, based on a silicon intrinsic substrate wafer. And the device structure is optimized to improve the maximum gain value in linear mode. Based on this, a new trench with an ion implantation type guard ring is designed to enhance the linear gain range. The simulation results show that the device operates in the wavelength range of 400~1100 nm and reaches the peak response at 700 nm. The breakdown voltage is 153 V, and the dark current at 90% breakdown voltage is 1.47 nA. The gain range is 2~101 under 32~138 V bias, with a large gain dynamic range and good linearity of gain, which is beneficial for the subsequent amplification circuit. Meanwhile, the calculation shows that the input optical power of APD device corresponding to the optical current compression degree of -1 dB is -16 dBm, which has good linearity in the range of -70~-16 dBm, which is beneficial to improve the overall performance of LIDAR.

In this paper, a hyperbolic-graded topological nanophotonic resonator is proposed to excite topologically protected edge states (TES). The index grading is introduced to modify the dispersion characteristics and enhance the mode field confinement of TES. The optimized structure leads to the excitation of a TES at a 1521nm operating wavelength. Further, the structural capability of the refractive index sensor is demonstrated. The analytical results demonstrate a sensitivity of 1806 nm/RIU (with a refractive index range from 1.35 to 1.40). Thus, showing its potential to detect and sense various biochemical analytes accurately.

Nature has implanted chirality in many organic molecules of living organisms that have made man think about exploiting this handedness property of the objects and coming up with exciting applications through synthetic chiral structures. In this connection, several chiral metasurface designs have been proposed with interesting optoelectronic applications, such as chiral sensing of a molecule at the zeptomole level, circularly polarized luminescence, circular dichroism, chiro-spintronics, and nonlinear optics. The perovskites' unique chirality features have led to the emerging perovskite optoelectronic area. In this regard, exploiting the novel chiral perovskite materials for optoelectronic functionalities becomes vitally important. This area of research is at a pre-mature stage. The present issues associated with perovskite semiconductors are toxicity, reproducibility, and instability. However, the expertise from physics, chemistry, and device engineering from the perovskite research community has been focusing on the basic material properties, fabrication, and characterization methods while simultaneously mitigating the present issues to get to successful commercialization. Future research opportunities related to chiral perovskite nanocrystals are versatile and intend to rationalize the exceptional potential of these low-cost materials for complicated optoelectronics applications.

We have fabricated a phototransistor based on multilayer MoTe2 and investigated its optical response. Under dark, the transistor exhibits ambipolar behavior with an on-off ratio of around 1000 for hole transport. The photocurrent of the transistor is modulated by illuminating the transistor with laser light and varying its power and the electrostatic gate voltage. We investigated the correlation between the laser power and the on/off ratio, photocurrent, and maximum current of the device. Finally, we analyzed the regions in the transfer curve that are least sensitive and most sensitive to incident laser light.