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Optoelectronics|53 Article(s)
Photonic analog signal processing and neuromorphic computing [Invited]
James Garofolo, and Ben Wu
In this review paper, we discuss the properties and applications of photonic computing and analog signal processing. Photonic computational circuits have large operation bandwidth, low power consumption, and fine frequency control, enabling a wide range of application-specific computational techniques that are impossible to implement using traditional electrical and digital hardware alone. These advantages are illustrated in the elegant implementation of optical steganography, the real-time blind separation of signals in the same bandwidth, and the efficient acceleration of artificial neural network inference. The working principles and use of photonic circuits for analog signal processing and neuromorphic computing are reviewed and notable demonstrated applications are highlighted. In this review paper, we discuss the properties and applications of photonic computing and analog signal processing. Photonic computational circuits have large operation bandwidth, low power consumption, and fine frequency control, enabling a wide range of application-specific computational techniques that are impossible to implement using traditional electrical and digital hardware alone. These advantages are illustrated in the elegant implementation of optical steganography, the real-time blind separation of signals in the same bandwidth, and the efficient acceleration of artificial neural network inference. The working principles and use of photonic circuits for analog signal processing and neuromorphic computing are reviewed and notable demonstrated applications are highlighted.
Chinese Optics Letters
- Publication Date: Mar. 21, 2024
- Vol. 22, Issue 3, 032501 (2024)
High-response formamidine bromide lead hybrid cadmium sulfide photodetector
Yao Liu, Lei Liu, Ruifeng Zhang, Weiye Yang, and Yingkai Liu
Organic–inorganic hybrid perovskite formamidinium lead bromide nanosheet (FAPbBr3 NS) is regarded as a superior substance used to construct optoelectronic devices. However, its uncontrollable stability seriously affects its application in the field of photodetectors. In this paper, FAPbBr3 is combined with cadmium sulfide nanobelt (CdS NB) to construct a hybrid device that greatly improves the stability and performance of the photodetector. The response of the FAPbBr3 NS/CdS NB detector under 490 nm light illumination reaches 5712 A/W, while the response of the FAPbBr3 photodetector under equivalent conditions is only 25.45 A/W. The photocurrent of the FAPbBr3 NS/CdS NB photodetector is nearly 80.25% of the initial device after exposure to air for 60 days. The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method. It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance. This paper presents a new possibility for high stability, fast response photodetectors. Organic–inorganic hybrid perovskite formamidinium lead bromide nanosheet (FAPbBr3 NS) is regarded as a superior substance used to construct optoelectronic devices. However, its uncontrollable stability seriously affects its application in the field of photodetectors. In this paper, FAPbBr3 is combined with cadmium sulfide nanobelt (CdS NB) to construct a hybrid device that greatly improves the stability and performance of the photodetector. The response of the FAPbBr3 NS/CdS NB detector under 490 nm light illumination reaches 5712 A/W, while the response of the FAPbBr3 photodetector under equivalent conditions is only 25.45 A/W. The photocurrent of the FAPbBr3 NS/CdS NB photodetector is nearly 80.25% of the initial device after exposure to air for 60 days. The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method. It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance. This paper presents a new possibility for high stability, fast response photodetectors.
Chinese Optics Letters
- Publication Date: Feb. 22, 2024
- Vol. 22, Issue 2, 022502 (2024)
Carrier transport barrier in AlGaN-based deep ultraviolet LEDs on offcut sapphire substrates
Qiushuang Chen, Li Chen, Cong Chen, Ge Gao, Wei Guo, and Jichun Ye
AlGaN-based light-emitting diodes (LEDs) on offcut substrates enhance radiative emission via forming carrier localization centers in multiple quantum wells (MQWs). This study introduces the carrier transport barrier concept, accessing its impact on the quantum efficiency of LEDs grown on different offcut sapphire substrates. A significantly enhanced internal quantum efficiency (IQE) of 83.1% is obtained from MQWs on the 1° offcut sapphire, almost twice that of the controlled 0.2° offcut sample. Yet, 1° offcut LEDs have higher turn-on voltage and weaker electroluminescence than 0.2° ones. Theoretical calculations demonstrate the existence of a potential barrier on the current path around the step-induced Ga-rich stripes. Ga-rich stripes reduce the turn-on voltage but restrict sufficient driving current, impacting LED performance. AlGaN-based light-emitting diodes (LEDs) on offcut substrates enhance radiative emission via forming carrier localization centers in multiple quantum wells (MQWs). This study introduces the carrier transport barrier concept, accessing its impact on the quantum efficiency of LEDs grown on different offcut sapphire substrates. A significantly enhanced internal quantum efficiency (IQE) of 83.1% is obtained from MQWs on the 1° offcut sapphire, almost twice that of the controlled 0.2° offcut sample. Yet, 1° offcut LEDs have higher turn-on voltage and weaker electroluminescence than 0.2° ones. Theoretical calculations demonstrate the existence of a potential barrier on the current path around the step-induced Ga-rich stripes. Ga-rich stripes reduce the turn-on voltage but restrict sufficient driving current, impacting LED performance.
Chinese Optics Letters
- Publication Date: Mar. 01, 2024
- Vol. 22, Issue 2, 022501 (2024)
Mid-wavelength nBn photodetector with high operating temperature and low dark current based on InAs/InAsSb superlattice absorber
Peng Cao, Tiancai Wang, Hongling Peng, Zhanguo Li, Qiandong Zhuang, and Wanhua Zheng
In this paper, we demonstrate nBn InAs/InAsSb type II superlattice (T2SL) photodetectors with AlAsSb as the barrier that targets mid-wavelength infrared (MWIR) detection. To improve operating temperature and suppress dark current, a specific Sb soaking technique was employed to improve the interface abruptness of the superlattice with device passivation using a SiO2 layer. These result in ultralow dark current density of 6.28×10-6 A/cm2 and 0.31 A/cm2 under -600 mV at 97 K and 297 K, respectively, which is lower than most reported InAs/InAsSb-based MWIR photodetectors. Corresponding resistance area product values of 3.20×104 Ω ·cm2 and 1.32 Ω ·cm2 were obtained at 97 K and 297 K. A peak responsivity of 0.39 A/W with a cutoff wavelength around 5.5 µm and a peak detectivity of 2.1×109 cm·Hz1/2/W were obtained at a high operating temperature up to 237 K. In this paper, we demonstrate nBn InAs/InAsSb type II superlattice (T2SL) photodetectors with AlAsSb as the barrier that targets mid-wavelength infrared (MWIR) detection. To improve operating temperature and suppress dark current, a specific Sb soaking technique was employed to improve the interface abruptness of the superlattice with device passivation using a SiO2 layer. These result in ultralow dark current density of 6.28×10-6 A/cm2 and 0.31 A/cm2 under -600 mV at 97 K and 297 K, respectively, which is lower than most reported InAs/InAsSb-based MWIR photodetectors. Corresponding resistance area product values of 3.20×104 Ω ·cm2 and 1.32 Ω ·cm2 were obtained at 97 K and 297 K. A peak responsivity of 0.39 A/W with a cutoff wavelength around 5.5 µm and a peak detectivity of 2.1×109 cm·Hz1/2/W were obtained at a high operating temperature up to 237 K.
Chinese Optics Letters
- Publication Date: Jan. 18, 2024
- Vol. 22, Issue 1, 012502 (2024)
Recent progress of parameter-adjustable high-power photonic microwave generation based on wide-bandgap photoconductive semiconductors
Tao Xun, Xinyue Niu, Langning Wang, Bin Zhang, Jinmei Yao, Yimu Yu, Hanwu Yang, Jing Hou, Jinliang Liu, and Jiande Zhang
Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability. Over the past several years, benefitting from the sustainable innovations in laser technology and the significant progress in materials technology, megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices. Here, we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode, including the mechanism, system architecture, critical technology, and experimental demonstration of the proposed high-power photonic microwave sources. The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed. Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability. Over the past several years, benefitting from the sustainable innovations in laser technology and the significant progress in materials technology, megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices. Here, we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode, including the mechanism, system architecture, critical technology, and experimental demonstration of the proposed high-power photonic microwave sources. The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.
Chinese Optics Letters
- Publication Date: Jan. 08, 2024
- Vol. 22, Issue 1, 012501 (2024)
Piezoelectric constant temperature dependence in strained [111]-oriented zinc-blende MQW-SOAs
Horacio Soto-Ortiz, and Gerson Torres-Miranda
Here, we present a study of the effective piezoelectric constant (e14e) temperature dependence in strained [111]-oriented zinc-blende quantum wells (QWs) embedded within a semiconductor optical amplifier (SOA). We determined e14e using a method that was insensitive to the segregation phenomenon and to the temperature dependence of the bandgap energy, which required neither fitting parameters nor temperature-dependent expressions for energy and out-of-plane effective masses of electrons and heavy holes. An e14e=-0.0534±0.0040 C · m-2 at 23°C was obtained for an SOA with 1.2 nm [111]-oriented strained In0.687Ga0.313As/In0.807Ga0.193As0.304P0.696 QWs. Unlike previously published research, where e14e magnitude increased as temperature rised, we extracted an e14e magnitude that decreased as temperature increased. Here, we present a study of the effective piezoelectric constant (e14e) temperature dependence in strained [111]-oriented zinc-blende quantum wells (QWs) embedded within a semiconductor optical amplifier (SOA). We determined e14e using a method that was insensitive to the segregation phenomenon and to the temperature dependence of the bandgap energy, which required neither fitting parameters nor temperature-dependent expressions for energy and out-of-plane effective masses of electrons and heavy holes. An e14e=-0.0534±0.0040 C · m-2 at 23°C was obtained for an SOA with 1.2 nm [111]-oriented strained In0.687Ga0.313As/In0.807Ga0.193As0.304P0.696 QWs. Unlike previously published research, where e14e magnitude increased as temperature rised, we extracted an e14e magnitude that decreased as temperature increased.
Chinese Optics Letters
- Publication Date: Aug. 22, 2023
- Vol. 21, Issue 9, 092501 (2023)
High-stability 4H-SiC avalanche photodiodes for UV detection at high temperatures
Xingye Zhou, Yuanjie Lü, Hongyu Guo, Xubo Song, Yuangang Wang, Shixiong Liang, Aimin Bu, and Zhihong Feng
In this work, high-stability 4H-SiC avalanche photodiodes (APDs) for ultraviolet (UV) detection at high temperatures are fabricated and investigated. With the temperature increasing from room temperature to 150°C, a very small temperature coefficient of 7.4 mV/°C is achieved for the avalanche breakdown voltage of devices. For the first time, the stability of 4H-SiC APDs is verified based on an accelerated aging test with harsh stress conditions. Three different stress conditions are selected with the temperatures and reverse currents of 175°C/100 µA, 200°C/100 µA, and 200°C/500 µA, respectively. The results show that our 4H-SiC APD exhibits robust high-temperature performance and can even endure more than 120 hours at the harsh aging condition of 200°C/500 µA, which indicates that 4H-SiC APDs are very stable and reliable for applications at high temperatures. In this work, high-stability 4H-SiC avalanche photodiodes (APDs) for ultraviolet (UV) detection at high temperatures are fabricated and investigated. With the temperature increasing from room temperature to 150°C, a very small temperature coefficient of 7.4 mV/°C is achieved for the avalanche breakdown voltage of devices. For the first time, the stability of 4H-SiC APDs is verified based on an accelerated aging test with harsh stress conditions. Three different stress conditions are selected with the temperatures and reverse currents of 175°C/100 µA, 200°C/100 µA, and 200°C/500 µA, respectively. The results show that our 4H-SiC APD exhibits robust high-temperature performance and can even endure more than 120 hours at the harsh aging condition of 200°C/500 µA, which indicates that 4H-SiC APDs are very stable and reliable for applications at high temperatures.
Chinese Optics Letters
- Publication Date: Oct. 28, 2022
- Vol. 21, Issue 3, 032502 (2023)
High-uniformity 2 × 64 silicon avalanche photodiode arrays with silicon multiple epitaxy technology
Tiancai Wang, Peng Cao, Hongling Peng, Chuanwang Xu, Haizhi Song, and Wanhua Zheng
In this paper, high-uniformity 2×64 silicon avalanche photodiode (APD) arrays are reported. Silicon multiple epitaxy technology was used, and the high performance APD arrays based on double-layer epiwafers are achieved for the first time, to the best of our knowledge. A high-uniformity breakdown voltage with a fluctuation of smaller than 3.5 V is obtained for the fabricated APD arrays. The dark currents are below 90 pA for all 128 pixels at unity gain voltage. The pixels in the APD arrays show a gain factor of larger than 300 and a peak responsivity of 0.53 A/W@M = 1 at 850 nm (corresponding to maximum external quantum efficiency of 81%) at room temperature. Quick optical pulse response time was measured, and a corresponding cutoff frequency up to 100 MHz was obtained. In this paper, high-uniformity 2×64 silicon avalanche photodiode (APD) arrays are reported. Silicon multiple epitaxy technology was used, and the high performance APD arrays based on double-layer epiwafers are achieved for the first time, to the best of our knowledge. A high-uniformity breakdown voltage with a fluctuation of smaller than 3.5 V is obtained for the fabricated APD arrays. The dark currents are below 90 pA for all 128 pixels at unity gain voltage. The pixels in the APD arrays show a gain factor of larger than 300 and a peak responsivity of 0.53 A/W@M = 1 at 850 nm (corresponding to maximum external quantum efficiency of 81%) at room temperature. Quick optical pulse response time was measured, and a corresponding cutoff frequency up to 100 MHz was obtained.
Chinese Optics Letters
- Publication Date: Oct. 14, 2022
- Vol. 21, Issue 3, 032501 (2023)
Generation of Lommel beams through highly scattering media|Editors' Pick
Shijie Tu, Qiannan Lei, Yangjian Cai, and Qian Zhao
Lommel beams have been potential candidates for optical communication and optical manipulation, due to their adjustable symmetry of transverse intensity distribution and continuously variable orbital angular momentum. However, the wavefront of the Lommel beam is scrambled when it transmits through highly scattering media. Here, we explore the construction of Lommel beams through highly scattering media with a transmission matrix-based point spread function engineering method. Experimentally, various Lommel beams with different parameters were generated through a ZnO scattering layer by use of a digital micromirror device. The construction of Lommel beams under high scattering is expected to benefit the optical applications behind highly scattering media. Lommel beams have been potential candidates for optical communication and optical manipulation, due to their adjustable symmetry of transverse intensity distribution and continuously variable orbital angular momentum. However, the wavefront of the Lommel beam is scrambled when it transmits through highly scattering media. Here, we explore the construction of Lommel beams through highly scattering media with a transmission matrix-based point spread function engineering method. Experimentally, various Lommel beams with different parameters were generated through a ZnO scattering layer by use of a digital micromirror device. The construction of Lommel beams under high scattering is expected to benefit the optical applications behind highly scattering media.
Chinese Optics Letters
- Publication Date: Jun. 15, 2022
- Vol. 20, Issue 9, 092501 (2022)
Germanium-on-silicon avalanche photodiode for 1550 nm weak light signal detection at room temperature
Yuxuan Li, Xiaobin Liu, Xuetong Li, Lanxuan Zhang, Baisong Chen, Zihao Zhi, Xueyan Li, Guowei Zhang, Peng Ye, Guanzhong Huang, Deyong He, Wei Chen, Fengli Gao, Pengfei Guo, Xianshu Luo, Guoqiang Lo, and Junfeng Song
To optimize the dark current characteristic and detection efficiency of the 1550 nm weak light signal at room temperature, this work proposes a Ge-on-Si avalanche photodiode (APD) in Geiger mode, which could operate at 300 K. This lateral separate absorption charge multiplication APD shows a low breakdown voltage (Vbr) in Geiger mode of -7.42 V and low dark current of 0.096 nA at unity gain voltage (VGain=1 = -7.03 V). Combined with an RF amplifier module and counter, the detection system demonstrates a low dark count rate (DCR) of 1.1×106 counts per second and high detection efficiency η of 7.8% for 1550 nm weak coherent pulse detection at 300 K. The APD reported in this work weakens the dependence of the weak optical signal recognition on the low environment temperature and makes single-chip integration of the single-photon level detection system possible. To optimize the dark current characteristic and detection efficiency of the 1550 nm weak light signal at room temperature, this work proposes a Ge-on-Si avalanche photodiode (APD) in Geiger mode, which could operate at 300 K. This lateral separate absorption charge multiplication APD shows a low breakdown voltage (Vbr) in Geiger mode of -7.42 V and low dark current of 0.096 nA at unity gain voltage (VGain=1 = -7.03 V). Combined with an RF amplifier module and counter, the detection system demonstrates a low dark count rate (DCR) of 1.1×106 counts per second and high detection efficiency η of 7.8% for 1550 nm weak coherent pulse detection at 300 K. The APD reported in this work weakens the dependence of the weak optical signal recognition on the low environment temperature and makes single-chip integration of the single-photon level detection system possible.
Chinese Optics Letters
- Publication Date: Apr. 27, 2022
- Vol. 20, Issue 6, 062501 (2022)
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