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Detectors|24 Article(s)
High-performance 4H-SiC p-i-n ultraviolet avalanche photodiodes with large active area
Xingye Zhou, Xin Tan, Yuangang Wang, Xubo Song, Tingting Han, Jia Li, Weili Lu, Guodong Gu, Shixiong Liang, Yuanjie Lü, and Zhihong Feng
Ultraviolet (UV) detectors with large photosensitive areas are more advantageous in low-level UV detection applications. In this Letter, high-performance 4H-SiC p-i-n avalanche photodiodes (APDs) with large active area (800 μm diameter) are reported. With the optimized epitaxial structure and device fabrication process, a high multiplication gain of 1.4 × 106 is obtained for the devices at room temperature, and the dark current is as low as ～10 pA at low reverse voltages. In addition, record external quantum efficiency of 85.5% at 274 nm is achieved, which is the highest value for the reported SiC APDs. Furthermore, the rejection ratio of UV to visible light reaches about 104. The excellent performance of our devices indicates a tremendous improvement for large-area SiC APD-based UV detectors. Finally, the UV imaging performance of our fabricated 4H-SiC p-i-n APDs is also demonstrated for system-level applications. Ultraviolet (UV) detectors with large photosensitive areas are more advantageous in low-level UV detection applications. In this Letter, high-performance 4H-SiC p-i-n avalanche photodiodes (APDs) with large active area (800 μm diameter) are reported. With the optimized epitaxial structure and device fabrication process, a high multiplication gain of 1.4 × 106 is obtained for the devices at room temperature, and the dark current is as low as ～10 pA at low reverse voltages. In addition, record external quantum efficiency of 85.5% at 274 nm is achieved, which is the highest value for the reported SiC APDs. Furthermore, the rejection ratio of UV to visible light reaches about 104. The excellent performance of our devices indicates a tremendous improvement for large-area SiC APD-based UV detectors. Finally, the UV imaging performance of our fabricated 4H-SiC p-i-n APDs is also demonstrated for system-level applications.
Chinese Optics Letters
- Publication Date: Sep. 10, 2019
- Vol. 17, Issue 9, 090401 (2019)
Ultra-compact four-lane hybrid-integrated ROSA based on three-dimensional microwave circuit design|On the Cover
Zeping Zhao, Jiaojiao Wang, Xueyan Han, Zhike Zhang, and Jianguo Liu
An ultra-compact hybrid-integration receiver optical subassembly (ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar lightwave circuit (PLC) arrayed waveguide grating (AWG) chip, a top-illuminated positive-intrinsic-negative photodetector array chip, and a three-dimensional microwave circuit that is specially designed for compact packaging. For each transmission lane, the 3 dB bandwidth of the ROSA is up to 20 GHz, and the maximum responsivity is up to 0.53 A/W. The proposed package structure can be used for smaller package sizes and would be an easy assembling solution for 100 GbE optical communication devices. An ultra-compact hybrid-integration receiver optical subassembly (ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar lightwave circuit (PLC) arrayed waveguide grating (AWG) chip, a top-illuminated positive-intrinsic-negative photodetector array chip, and a three-dimensional microwave circuit that is specially designed for compact packaging. For each transmission lane, the 3 dB bandwidth of the ROSA is up to 20 GHz, and the maximum responsivity is up to 0.53 A/W. The proposed package structure can be used for smaller package sizes and would be an easy assembling solution for 100 GbE optical communication devices.
Chinese Optics Letters
- Publication Date: Mar. 10, 2019
- Vol. 17, Issue 3, 030401 (2019)
Impulse response of Ge2Sb2Te5-based ultrafast photodetector integrated with SOI waveguide
Vibhu Srivastava, Prateek Mishra, and Sunny
The impulse response for a phase-change material Ge2Sb2Te5 (GST)-based photodetector integrated with a silicon-on-insulator (SOI) waveguide is simulated using finite difference time domain method. The current is calculated by solving the drift-diffusion model for short pulse (～10 fs) excitation for both of the stable phases. Full width at half-maximum values of less than 1 ps are found in the investigation. The crystalline GST has higher 3 dB bandwidth than the amorphous GST at a 1550 nm wavelength with responsivities of 21 A/W and 18.5 A/W, respectively, for a 150 nm thick GST layer biased at 2 V. A broad spectrum can be utilized by tuning the device using the phase-change property of material in the near infrared region. The impulse response for a phase-change material Ge2Sb2Te5 (GST)-based photodetector integrated with a silicon-on-insulator (SOI) waveguide is simulated using finite difference time domain method. The current is calculated by solving the drift-diffusion model for short pulse (～10 fs) excitation for both of the stable phases. Full width at half-maximum values of less than 1 ps are found in the investigation. The crystalline GST has higher 3 dB bandwidth than the amorphous GST at a 1550 nm wavelength with responsivities of 21 A/W and 18.5 A/W, respectively, for a 150 nm thick GST layer biased at 2 V. A broad spectrum can be utilized by tuning the device using the phase-change property of material in the near infrared region.
Chinese Optics Letters
- Publication Date: Oct. 10, 2019
- Vol. 17, Issue 10, 100401 (2019)
A proposed approach for detecting terahertz pulses by using double few-cycle laser pulses with opposite carrier envelope phases
Kejia Wang, Xinyang Gu, Zhenwei Zhang, Zhengang Yang, Jinsong Liu, and Shenglie Wang
Previous research shows that few-cycle laser (FCL) pulses with low energy and without a bias field can be used to coherently detect terahertz (THz) pulses. As we know, it is very difficult to stabilize the carrier envelope phase (CEP) of FCL pulses, i.e., there are some random fluctuations for the CEP. Here we theoretically investigate the influence of such instability on the accuracy of THz detection. Our results show that although there is an optimum CEP for THz detection, the fluctuations of the CEP will lead to terrible thorns on the detected THz waveform. In order to solve this problem, we propose an approach using two few-cycle laser pulses with opposite CEPs, i.e., their CEPs are differed by π. Previous research shows that few-cycle laser (FCL) pulses with low energy and without a bias field can be used to coherently detect terahertz (THz) pulses. As we know, it is very difficult to stabilize the carrier envelope phase (CEP) of FCL pulses, i.e., there are some random fluctuations for the CEP. Here we theoretically investigate the influence of such instability on the accuracy of THz detection. Our results show that although there is an optimum CEP for THz detection, the fluctuations of the CEP will lead to terrible thorns on the detected THz waveform. In order to solve this problem, we propose an approach using two few-cycle laser pulses with opposite CEPs, i.e., their CEPs are differed by π.
Chinese Optics Letters
- Publication Date: Sep. 10, 2018
- Vol. 16, Issue 9, 090401 (2018)
Large-area 4H-SiC avalanche photodiodes with high gain and low dark current for visible-blind ultraviolet detection
Xingye Zhou, Jia Li, Weili Lu, Yuangang Wang, Xubo Song, Shunzheng Yin, Xin Tan, Yuanjie Lü, Hongyu Guo, Guodong Gu, and Zhihong Feng
In this Letter, we report large-area (600 μm diameter) 4H-SiC avalanche photodiodes (APDs) with high gain and low dark current for visible-blind ultraviolet detection. Based on the separate absorption and multiplication structure, 4H-SiC APDs passivated with SiNx instead of SiO2 are demonstrated for the first time, to the best of our knowledge. Benefitting from the SiNx passivation, the surface leakage current is effectively suppressed. At room temperature, high multiplication gain of 6.5×105 and low dark current density of 0.88 μA/cm2 at the gain of 1000 are achieved for our devices, which are comparable to the previously reported small-area SiC APDs. In this Letter, we report large-area (600 μm diameter) 4H-SiC avalanche photodiodes (APDs) with high gain and low dark current for visible-blind ultraviolet detection. Based on the separate absorption and multiplication structure, 4H-SiC APDs passivated with SiNx instead of SiO2 are demonstrated for the first time, to the best of our knowledge. Benefitting from the SiNx passivation, the surface leakage current is effectively suppressed. At room temperature, high multiplication gain of 6.5×105 and low dark current density of 0.88 μA/cm2 at the gain of 1000 are achieved for our devices, which are comparable to the previously reported small-area SiC APDs.
Chinese Optics Letters
- Publication Date: Jun. 10, 2018
- Vol. 16, Issue 6, 060401 (2018)
Terahertz wave generation via pre-ionized air plasma
Kai Kang, Liangliang Zhang, Tong Wu, Kai Li, and Cunlin Zhang
We report the terahertz (THz) wave generation from a single-color scheme modulated by pre-ionized air plasma via an orthogonal pumping geometry. It is found that the amplitude of the THz signal generated by the pump beam tends to decrease gradually with the increase of the modulation power. We believe that the ponderomotive force plays an important role in the process of the interaction between the pump beam and the pre-ionization beam. The hydrostatic state of the electrostatic separation field caused by the modulation beam will directly affect the generation efficiency of the THz wave. Our results contribute to further understanding of the theoretical mechanism and expanding of the practical applications of THz wave generation and modulation. We report the terahertz (THz) wave generation from a single-color scheme modulated by pre-ionized air plasma via an orthogonal pumping geometry. It is found that the amplitude of the THz signal generated by the pump beam tends to decrease gradually with the increase of the modulation power. We believe that the ponderomotive force plays an important role in the process of the interaction between the pump beam and the pre-ionization beam. The hydrostatic state of the electrostatic separation field caused by the modulation beam will directly affect the generation efficiency of the THz wave. Our results contribute to further understanding of the theoretical mechanism and expanding of the practical applications of THz wave generation and modulation.
Chinese Optics Letters
- Publication Date: Nov. 10, 2018
- Vol. 16, Issue 11, 110401 (2018)
External quantum efficiency-enhanced PtSi Schottky-barrier detector utilizing plasmonic ZnO:Al nanoparticles and subwavelength gratings
Bingxin Kang, Yi Cai, and Lingxue Wang
A infrared light trapping structure combining front subwavelength gratings and rear ZnO:Al nanoparticles for a PtSi Schottky-barrier detector over a 3–5 μm waveband is theoretically investigated. By selecting the proper plasmonic material and optimizing the parameters for the proposed structure, the absorption of the PtSi layer is dramatically improved. The theoretical results show that this improvement eventually translates into an equivalent external quantum efficiency (EQE) enhancement of 2.46 times at 3–3.6 μm and 2.38 times at 3.6–5 μm compared to conventional structures. This improvement in the EQE mainly lies in the increase of light path lengths within the PtSi layer by the subwavelength grating diffraction and nanoparticle-scattering effects. A infrared light trapping structure combining front subwavelength gratings and rear ZnO:Al nanoparticles for a PtSi Schottky-barrier detector over a 3–5 μm waveband is theoretically investigated. By selecting the proper plasmonic material and optimizing the parameters for the proposed structure, the absorption of the PtSi layer is dramatically improved. The theoretical results show that this improvement eventually translates into an equivalent external quantum efficiency (EQE) enhancement of 2.46 times at 3–3.6 μm and 2.38 times at 3.6–5 μm compared to conventional structures. This improvement in the EQE mainly lies in the increase of light path lengths within the PtSi layer by the subwavelength grating diffraction and nanoparticle-scattering effects.
Chinese Optics Letters
- Publication Date: Jul. 10, 2016
- Vol. 14, Issue 7, 070401 (2016)
Enhanced solar-blind ultraviolet single-photon detection with a Geiger-mode silicon avalanche photodiode
Yafan Shi, Zhaohui Li, Baicheng Feng, Peiqin Yan, Bingcheng Du, Hui Zhou, Haifeng Pan, and Guang Wu
Solar-blind ultraviolet detection is of great importance in astronomy and industrial and military applications. Here, we report enhanced solar-blind ultraviolet single-photon detection by a normal silicon avalanche photodiode (Si APD) single-photon detector with a specially designed photon-collecting device. By re-focusing the reflected photon from the Si chip surface on the detection area by the aluminum-coated hemisphere, the detection efficiency of the Si APD at 280 nm can be improved to 4.62%. This system has the potential for high-efficiency photon detection in the solar-blind ultraviolet regime with low noise. Solar-blind ultraviolet detection is of great importance in astronomy and industrial and military applications. Here, we report enhanced solar-blind ultraviolet single-photon detection by a normal silicon avalanche photodiode (Si APD) single-photon detector with a specially designed photon-collecting device. By re-focusing the reflected photon from the Si chip surface on the detection area by the aluminum-coated hemisphere, the detection efficiency of the Si APD at 280 nm can be improved to 4.62%. This system has the potential for high-efficiency photon detection in the solar-blind ultraviolet regime with low noise.
Chinese Optics Letters
- Publication Date: Mar. 10, 2016
- Vol. 14, Issue 3, 030401 (2016)
Experimental investigation of the startup time difference between high-speed cameras
Yanyan Cao, Chao Wang, Qinwei Ma, and Shaopeng Ma
High-speed cameras are widely used in experimental research and industrial measurement. Although multiple cameras are commonly used, whether the cameras are triggered at the same time is typically overlooked. This study measures the startup time difference between two high-speed cameras employing a proposed measuring system. A series of comparative experiments was conducted to consider the complex factors that can lead to a time difference. The system recorded the startup time differences for different combinations of two cameras at different frame rates, and thus acquired the dependence of the time difference on these factors. Suggestions are made on the basis of the experimental results. High-speed cameras are widely used in experimental research and industrial measurement. Although multiple cameras are commonly used, whether the cameras are triggered at the same time is typically overlooked. This study measures the startup time difference between two high-speed cameras employing a proposed measuring system. A series of comparative experiments was conducted to consider the complex factors that can lead to a time difference. The system recorded the startup time differences for different combinations of two cameras at different frame rates, and thus acquired the dependence of the time difference on these factors. Suggestions are made on the basis of the experimental results.
Chinese Optics Letters
- Publication Date: Jul. 10, 2015
- Vol. 13, Issue 7, 070401 (2015)
Light source system for high-precision flat-field correction and the calibration of an array detector
Fugui Yang, Qiushi Wang, and Ming Li
Signal distortion due to the non-uniform response of the detector degrades the measurement accuracy of most metrology instruments. In this Letter, we report a newly developed calibration source system for reference-based non-uniformity correction using a laser source, a fiber, and a diffusive module. By applying the Monte Carlo simulation, we show that the transmittance of the system highly depends on the cavity reflection of the diffusive module. We also demonstrate the use of this system to achieve a flat field at a very low non-uniformity (less than 0.2%) with proper illumination intensity, which most costly commercial integrating sphere systems traditionally cannot provide. Signal distortion due to the non-uniform response of the detector degrades the measurement accuracy of most metrology instruments. In this Letter, we report a newly developed calibration source system for reference-based non-uniformity correction using a laser source, a fiber, and a diffusive module. By applying the Monte Carlo simulation, we show that the transmittance of the system highly depends on the cavity reflection of the diffusive module. We also demonstrate the use of this system to achieve a flat field at a very low non-uniformity (less than 0.2%) with proper illumination intensity, which most costly commercial integrating sphere systems traditionally cannot provide.
Chinese Optics Letters
- Publication Date: Apr. 10, 2015
- Vol. 13, Issue 4, 040402 (2015)
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