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Linewidth narrowing in self-injection-locked on-chip lasers

Light(Science & Applications) 2023年第10期12卷 2074-2083页

作者： Emad Alkhazraji Weng W.Chow Frédéric Grillot John E.Bowers Yating Wan Integrated Photonics Lab King Abdullah University of Science and TechnologyThuwal 23955Saudi Arabia Sandia National Laboratories AlbuquerqueNM 87185-1086USA LTCI Télécom ParisInstitut Polytechnique de Paris91120 PalaiseauFrance Department of Electronic and Computer Engineering University of California-Santa BarbaraSanta BarbaraCA 93106USA

Stable laser emission with narrow linewidth is of critical importance in many applications,including coherent communications,LIDAR,and remote *** this work,the physics underlying spectral narrowing of self-injection-locked on-chip lasers to Hz-level lasing linewidth is investigated using a composite-cavity *** integrated III–v/SiN lasers operating with quantum-dot and quantum-well active regions are analyzed with a focus on the effects of carrier quantum *** intrinsic differences are associated with gain saturation and carrier-induced refractive index,which are directly connected with 0-and 2-dimensional carrier densities of *** from parametric studies are presented for tradeoffs involved with tailoring the linewidth,output power,and injection current for different device *** both quantum-well and quantum-dot devices show similar linewidth-narrowing capabilities,the former emits at a higher optical power in the self-injection-locked state,while the latter is more ***,a multi-objective optimization analysis is provided to optimize the operation and design *** the quantum-well laser,minimizing the number of quantum-well layers is found to decrease the threshold current without significantly reducing the output *** the quantum-dot laser,increasing the quantum-dot layers or density in each layer increases the output power without significantly increasing the threshold *** findings serve to guide more detailed parametric studies to produce timely results for engineering design.

关键词： narrowing injection quantum

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Ultrafast Plasmonics for All-optical Switching and Pulsed Lasers

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Ultrafast Science 2024年第4期4卷 29-61页

作者： Muhammad Aamir Iqbal Wang Lin Wang Pengyun Jianrong Qiu Xiaofeng Liu School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China State Key Lab of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

Surface plasmon resonances(SPRs)are often regarded as the collective oscillations of charge carriers localized at the dielectric–metal interface that display an ultrafast response upon light *** recent developments in the fabrication and characterization of plasmonic nanostructures have stimulated continuous effects in the search for their potential applications in the photonic *** on the role of plasmonics in photonics,this review covers recent advances in ultrafast plasmonic materials with a prime focus on all-optical *** phenomena of plasmonic light–matter interaction and plasmon dynamics are discussed by elaborating on the ultrafast processes unraveled by both experimental and theoretical methods,along with a comprehensive illustration of leveraging ultrafast plasmonics for all-optical switching and pulse laser generation with a focus on device design and *** review is concluded with a brief highlight of the current progress and the potential future directions in ultrafast plasmonics.

关键词： Switching collective illustration

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design optimization of a 1-D array of stemless plastic scintillation detectors

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MEDICAL PHYSICS 2025年第4期52卷 2560-2569页

作者： Aynehband, Samaneh Hill, Ian G. Syme, Alasdair Dalhousie Univ Dept Phys & Atmospher Sci 5820 Univ AveDickson BldgRm 3030 Halifax NS B3H 1V7 Canada Dalhousie Univ Dept Radiat Oncol Halifax NS Canada Nova Scotia Hlth Author QEII Hlth Sci Ctr Dept Med Phys Halifax NS Canada

BackgroundA stemless plastic scintillation detector (SPSD) is composed of an organic plastic scintillator coupled to an organic photodiode. Previous research has shown that SPSDs are ideally suited to challenging dosimetry measurements such as output factors and profiles in small fields. Lacking from the current literature is a systematic effort to optimize the performance of the photodiode component of the detector. An optimized detector could permit a reduction in detector element size, thus improving spatial resolution without degradation of the signal to noise ratio values seen *** use an organic photodiode coupled to a plastic scintillator to measure ionizing radiation fields. The design retains the benefits of plastic scintillation detectors (energy and dose rate independence, no perturbation factors, etc.) but avoids the challenges of optical fiber-based systems (Cerenkov radiation). In this work, the design of a 1-dimensional array of SPSDs is optimized to maximize the measured ***-covered PET was etched using hydrochloric acid, and the substrate was cleaned. PEDOT: PSS and P3HT: PCBM (different weight ratios) were then applied to the substrate using spin-coating. Finally, aluminum top electrodes were added using vacuum thermal evaporation to complete the fabrication process. The variables studied for the optimization included: spin coater's speed (i.e., film thickness), P3HT: PCBM ratio, solution concentration, and scintillator *** the film thickness from similar to 80 nm to similar to 138 nm increased the measured signal by a factor of approximately 7.7. Changing the ratio of P3HT to PCBM from (1:1) to (4:1) resulted in approximately 3.5 times higher signal. Additionally, increasing the total concentration of the solution from 2% to 4% by weight ratio increased the signal by roughly a factor of 2.5 for a P3HT: PCBM ratio of 2:1. However, for a P3HT: PCBM ratio of 4:1, increased solution concentration

关键词： organic detector radiation scintillator small-field dosimetry stemless plastic scintillation detector

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Optoelectronic co-optimization of high-performance dual-port Ge/Si lateral photodetector with side confinement trenches 2

Optoelectronic co-optimization of high-performance dual-port...

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2nd International Academic Conference on Optics and Photonics, IACOP 2024

作者： Cheng, Jialin Yan, Huimin Zhang, Shuojian Liu, Biaohan He, Jian-Jun State Key Laboratory of Extreme Photonics and Instrumentation Centre for Integrated Optoelectronics College of Optical Science and Engineering Zhejiang University Hangzhou310027 China

ISBN: (数字)9781510688827

ISBN: (纸本)9781510688810

Photodetectors, which convert optical signals into electrical signals, are critical components in integrated silicon photonic platforms. This paper introduces a high-performance Ge/Si lateral photodetector design with dual-port incidence and confinement trenches on both sides. Compared to one-port incidence, the dual-port design significantly improves the light field and the distribution of photogenerated carriers in the Ge region. The confinement trenches in the Si layer on both sides of the Ge focus light more effectively into the Ge region, enhancing absorption efficiency and boosting responsivity. Following optoelectronic co-optimization, the 64-PD array, fabricated through MPW service, demonstrates high performance: dark current below 3 nA, O-band responsivity above 0.92 A/W, and small-signal bandwidth over 34 GHz at 3 v bias. The large-signal eye diagram test achieves a rate above 36 Gbps, limited by the 40 Gbps test system. The PD array exhibits consistent performance, making it highly suitable for applications in optical interconnects and optical computing. © 2025 SPIE.

关键词： Silicon photonics

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Illumination uniformity control of EPE using PvG on AR waveguide design 5

Illumination uniformity control of EPE using PVG on AR waveg...

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optical Architectures for Displays and Sensing in Augmented, virtual, and Mixed Reality (AR, vR, MR) v 2024

作者： Chiang, Nien-Jung Huang, Ting-Wei Zhang, Bo-Kai Sheng, Ji-Ping Hung, Wen-Chang Cheng, Yu-Chieh Department of Electro-Optical Engineering Taipei Tech No. 1 Sec. 3 Zhongxiao E. Rd. Da'an Dist. Taipei10608 Taiwan ASUSTeK COMPUTER INC No. 115 Li-De Rd. Beitou Dist. Taipei112019 Taiwan

ISBN: (纸本)9781510670860

current augmented reality (AR) waveguide display technology faces a challenging trade-off between essential factors such as eyebox, efficiency, and image uniformity. Surface relief grating has been a commonly used exit pupil expander (EPE) in waveguides, but it exhibits limitations in efficiency and uniformity. To overcome these shortcomings, polarized volume grating (PvG) with ultra-wide angular bandwidth and high efficiency has been employed as an EPE to enhance efficiency and uniformity. However, the challenge arises when attempting to achieve high uniformity within the eyebox using nematic liquid crystal for controlling each expansion, as the polarization changes of diffracted light contribute to varying diffraction efficiencies, which affects the maintenance of uniformity across the entire field of view. This article introduces an innovative approach by incorporating high-low cover-layers on top of PvG to effectively control the path difference between light rays at various angles. This design modification mitigates unnecessary out-coupling and ensures a remarkably high level of uniformity in the entire AR system, providing a more efficient and uniform expanded eyebox. © 2024 SPIE.

关键词： Augmented reality

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Sensitive Inter-turn Fault Detection Approach for Induction Motor Under various Operating Conditions

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ARABIAN JOURNAL FOR SCIENCE AND engineering 2023年第8期48卷 10787-10801页

作者： Gundewar, Swapnil K. Kane, Prasad v. Visvesvaraya Natl Inst Technol Dept Mech Engn Nagpur 440010 Maharashtra India

Induction motor fault diagnosis and condition monitoring are on the anvil of researchers, who have reported many studies and developments in the literature. However, the reported technique requires intervention to interpret the frequency and time-frequency domain analysis results. Intelligent systems have been reported to overcome these limitations;however, time delays and additional costs are incurred owing to the need for expert interpretation. Hence, this work proposes a methodology based on motor current signal processing in image format to automatically diagnose and classify the inter-turn fault of the three-phase induction motor. The motor current sampled in the time domain by shortening the inter turns in the winding for different load conditions is expressed as three-color monotonous images for each phase. These obtained images are applied for training and testing of convolution neural network, which can classify the faults according to their severity and identify the phase in which the fault prevails. Furthermore, efforts have been made to design the convolution neural network architecture, i.e., selecting hyperparameters such as learning rate, batch size, number of epochs, and momentum rate, and average classification accuracy of 99.38% is obtained. The proposed technique with monotonous coloured images of current signal as an input to CNN is found to be effective in terms of computational time, robustness to identify the faults even in the presence of noise and fault classification accuracy when compared to other published literature.

关键词： Stator fault Fault detection Convolution neural network Hyperparameters

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design of a low noise avalanche photodiode with integrated dark pixel

Design of a low noise avalanche photodiode with integrated d...

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2024 Asia Communications and Photonics Conference, ACP 2024 and International Conference on Information Photonics and optical Communications, IPOC 2024

作者： Pang, Xin Tong, Xuanke Zhu, Rongjie Zou, Yi Deng, Shijie School of Optoelectronic Engineering Guilin University of Electronic Technology Guilin China Guilin University of Electronic Technology Guilin China

ISBN: (纸本)9798350379266

This paper proposes a novel structure for the silicon avalanche photodiode. The structure uses an integrated dark pixel to offset the dark current of the avalanche photodiode, effectively reducing the output noise. The device structure is simulated by software to extract the relevant electrical and optical properties. The results show that the breakdown voltage of the avalanche photodiode is 33.6 v at 300 K, the breakdown current is less than 1×10-10 A, and the output current values under light and dark conditions at different temperatures differ by at least 5 orders of magnitude. Under 0 v bias voltage, the device exhibits the highest quantum efficiency of 35%, and it has a high response in the wavelength range of 400 ~ 800 nm, with a peak responsivity of 0.14 A/W at 540 nm. In addition, under 6.4v overbias, the avalanche probability in the light-receiving region is the same as that within the integrated dark pixel, the maximum avalanche breakdown probability reaches 83%, and the peak electric field is about 4.6×105 v/cm. © 2024 IEEE.

关键词： Avalanche photodiodes

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design and implementation of LED driver circuit applied to fluorescent optical fiber temperature sensor 9

Design and implementation of LED driver circuit applied to f...

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9th International Conference on Electromechanical Control Technology and Transportation, ICECTT 2024

作者： Liu, Qing Wang, Yang Pan, Xuan School of Physics and Optoelectronics Xiangtan University Xiangtan411105 China

ISBN: (纸本)9781510682399

The 0.18 um CMOS process is used to develop a high-precision power-adjustable LED driver circuit for the hardware circuit of a fluorescent fiber-optic temperature sensor. The driver circuit uses the microcontroller system's vDAC conversion output voltage to create a controlled constant-current source, and it is based on the operational amplifier to create the topology of current series negative feedback. The conversion output voltage vDAC is adaptively adjusted to display the fluorescent signal produced by the fluorescent material excited by the LED driver circuit, correctly. The accurate temperature value can be output by the sensor. This circuit has finished the tape out and testing. The findings indicate that the output current may attain a current regulation range of 12 mA under various supply voltage changes, with vDAC varying from 0 to 3.3 v. The output current is barely impacted by temperature, and the change in output current with vDAC at various temperatures is investigated at 4.5 v supply voltage. The circuit shutdown time at 20 Hz frequency is 21.35 us. Good circuit performance makes it suitable for use in fluorescent fiber-optic temperature sensors. © 2024 SPIE.

关键词： Light emitting diodes

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developments toward monolithic III-N microLEDs: red InGaN active region and tunnel junctions grown by MOCvD 29

Developments toward monolithic III-N microLEDs: red InGaN ac...

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Light-Emitting Devices, Materials, and Applications XXIX 2025

作者： Wong, Matthew S. Tak, Tanay Quevedo, Alejandro Li, Panpan Smith, Jordan M. Ewing, Jacob J. Rienzi, vincent Nakamura, Shuji Speck, James S. DenBaars, Steven P. Materials Department University of California Santa BarbaraCA93106 United States Department of Electrical and Computer Engineering University of California Santa BarbaraCA93106 United States

ISBN: (纸本)9781510685208

As the display technology is expanding rapidly into wearable and near-eye displays, different novel approaches are being developed to enable the emerging display applications. III-nitride microLEDs have been considered as a potential solution that reveals the possibility of high-resolution displays with ultrahigh brightness and outstanding operating lifespan. Among different methods to realize full-color microLED displays, monolithic microLEDs offer advantages in mass transfer, device fabrication, and integration processes. The monolithic microLED approach takes advantage of the wavelength tunability within the visible spectrum covering red, green, and blue (RGB) emission by controlling the indium incorporation in the active region. The concept of monolithic InGaN RGB LEDs have been demonstrated in the literature, but the electrical efficiency is low because of the inefficient injection efficiency in long-wavelength active region and the voltage penalty from tunnel junctions (TJs). For the long-wavelength active region, the method is to intentionally control the v-defect formation by opening and filling up the v-defects by growth conditions. The use of v-defect engineering in the active region has shown to promote injection efficiency especially in the green and red LEDs. On the other hand, a fabrication method is discussed that results in low voltage penalty by enhancing the efficacy of sidewall activation of the TJs in microLEDs. The two methods present in this work will enhance the electrical efficiency in the long-wavelength active region and the TJ performance that can be applied in the monolithic LED design. © 2025 SPIE.

关键词： Light emitting diodes

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Inferring the solution space of microscope objective lenses using deep learning

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OPTICS EXPRESS 2022年第5期30卷 6531-6545页

作者： Cote, Geoffroi Zhang, Yueqian Menke, Christoph Lalonde, Jean-Francois Thibault, Simon Univ Laval Quebec City PQ G1V 0A6 Canada Carl Zeiss D-07745 Jena Germany Carl Zeiss D-73446 Oberkochen Germany

Lens design extrapolation (LDE) is a data-driven approach to optical design that aims to generate new optical systems inspired by reference designs. Here, we build on a deep learning-enabled LDE framework with the aim of generating a significant variety of microscope objective lenses (MOLs) that are similar in structure to the reference MOLs, but with varied sequences-defined as a particular arrangement of glass elements, air gaps, and aperture stop placement. We first formulate LDE as a one-to-many problem-specifically, generating varied lenses for any set of specifications and lens sequence. Next, by quantifying the structure of a MOL from the slopes of its marginal ray, we improve the training objective to capture the structures of the reference MOLs (e.g., Double-Gauss, Lister, retrotbcus, etc.). From only 34 reference MOLs, we generate designs across 7432 lens sequences and show that the inferred designs accurately capture the structural diversity and performance of the dataset. Our contribution answers two current challenges of the LDE framework: incorporating a meaningful one-to-many mapping, and successfully extrapolating to lens sequences unseen in the dataset-a problem much harder than the one of extrapolating to new specifications. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Geometric optics Image quality Lens design optical design optical design software optical systems

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