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OPTOELECTRONICS|215 Article(s)
Spintronic Terahertz Emission Spectroscopy Based on Ultrafast Terahertz Scattering Scanning Near-Field Optical Microscope (Invited)
Jiaqi Wang, Mingcong Dai, Yihang Ma, Youwei Wang, Zijian Zhang, Jiahua Cai, Peng Chen, Caihua Wan, Xiufeng Han, and Xiaojun Wu
Spintronic terahertz (THz) emitters offer distinct advantages such as high efficiency, ultrabroadband capability, low cost, and easy integration. These emitters find applications not only in THz time-domain spectrometers driven by high-repetition-rate laser oscillators but also in the generation of intense THz electromagnetic pulses powered by high-energy femtosecond laser amplifiers. They have proven valuable in THz spectroscopy imaging and the exploration of strong-field THz physics. However, previous research on spintronic THz radiation mechanisms and device development relies primarily on far-field THz time-domain spectroscopy. The results of this approach present average THz emission information for the laser-pumped spot areas, which does not provide any insights into ultrafast spin currents and THz emission properties for the materials at micro- and nano-scales. In this study, we employ ultrafast THz scattering scanning near-field optical microscopy, driven by a femtosecond fiber laser oscillator, to investigate the spintronic terahertz emission properties of the ferromagnetic heterojunction material W/CoFeB/Pt at nanoscale. The utilization of this technology enables the detection of high signal-to-noise ratio spintronic THz emission at transverse scales as small as hundreds nanometers. This novel approach explores the generation, detection, and manipulation of ultrafast spin currents at THz frequencies with nano-spatial resolution. This study may inspire innovative ideas for the advancement of ultrafast THz spin optoelectronics. Spintronic terahertz (THz) emitters offer distinct advantages such as high efficiency, ultrabroadband capability, low cost, and easy integration. These emitters find applications not only in THz time-domain spectrometers driven by high-repetition-rate laser oscillators but also in the generation of intense THz electromagnetic pulses powered by high-energy femtosecond laser amplifiers. They have proven valuable in THz spectroscopy imaging and the exploration of strong-field THz physics. However, previous research on spintronic THz radiation mechanisms and device development relies primarily on far-field THz time-domain spectroscopy. The results of this approach present average THz emission information for the laser-pumped spot areas, which does not provide any insights into ultrafast spin currents and THz emission properties for the materials at micro- and nano-scales. In this study, we employ ultrafast THz scattering scanning near-field optical microscopy, driven by a femtosecond fiber laser oscillator, to investigate the spintronic terahertz emission properties of the ferromagnetic heterojunction material W/CoFeB/Pt at nanoscale. The utilization of this technology enables the detection of high signal-to-noise ratio spintronic THz emission at transverse scales as small as hundreds nanometers. This novel approach explores the generation, detection, and manipulation of ultrafast spin currents at THz frequencies with nano-spatial resolution. This study may inspire innovative ideas for the advancement of ultrafast THz spin optoelectronics.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0325001 (2024)
Research Progress in Full-Color Display of Micro-Light-Emitting Diode (Invited)
Lixiang Huang, Bing Han, Long Yan, Xiangjie Zhao, Youliang Zhu, Xiao Lin, Ziwei Li, and Anlian Pan
Display technology that uses light-emitting diodes is extensively used in devices such as televisions, computers, and mobile phones. Compared to traditional liquid crystal displays and organic light-emitting diode screens, the micro-light-emitting diode (Micro-LED) displays offer notable benefits in size, performance, power efficiency, and lifespan. We provide an overview of the technology types and application scenarios of full-color Micro-LED displays, describe the latest research in creating full-color displays using Micro-LED, including massive transfer technology, color conversion layer integration technology, and epitaxial chip monolithic integration technology. Furthermore, we compare the strengths and weaknesses of these technologies and look ahead the future evolution of Micro-LED-based full-color display technology. Display technology that uses light-emitting diodes is extensively used in devices such as televisions, computers, and mobile phones. Compared to traditional liquid crystal displays and organic light-emitting diode screens, the micro-light-emitting diode (Micro-LED) displays offer notable benefits in size, performance, power efficiency, and lifespan. We provide an overview of the technology types and application scenarios of full-color Micro-LED displays, describe the latest research in creating full-color displays using Micro-LED, including massive transfer technology, color conversion layer integration technology, and epitaxial chip monolithic integration technology. Furthermore, we compare the strengths and weaknesses of these technologies and look ahead the future evolution of Micro-LED-based full-color display technology.
Laser & Optoelectronics Progress
- Publication Date: Jan. 10, 2024
- Vol. 61, Issue 1, 0125001 (2024)
Multiple Fano Resonances and Optical Sensing Based on C3-Symmetry-Breaking
Jingzhao Zhang, Xiaoqing Luo, Xiaofeng Xu, Youlin Luo, Weihua Zhu, Zhiyong Chen, and Xinlin Wang
In this study, we numerically investigate surface plasmonic triple Fano resonances and optical sensing in the near-infrared band using a hybrid metasurface consisting of concentric C3-hole and circular-ring-aperture unit cells. The results reveal that by changing the symmetry breaking of the C3 unit cells, we can not only induce a tunable multi Fano resonance effect but also enable self-reference optical sensing. In addition, a radiation monitoring sensing capability, which depends on the depth of the Fano dips, can be realized by varying the inner radius of the circular-ring-aperture unit cells. Our results provide a new perspective for the design of compact and tunable Fano resonance photonic devices and enable the incorporation of periodic subwavelength metal nanostructures into relevant biosensing and optical communication applications. In this study, we numerically investigate surface plasmonic triple Fano resonances and optical sensing in the near-infrared band using a hybrid metasurface consisting of concentric C3-hole and circular-ring-aperture unit cells. The results reveal that by changing the symmetry breaking of the C3 unit cells, we can not only induce a tunable multi Fano resonance effect but also enable self-reference optical sensing. In addition, a radiation monitoring sensing capability, which depends on the depth of the Fano dips, can be realized by varying the inner radius of the circular-ring-aperture unit cells. Our results provide a new perspective for the design of compact and tunable Fano resonance photonic devices and enable the incorporation of periodic subwavelength metal nanostructures into relevant biosensing and optical communication applications.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2023
- Vol. 60, Issue 9, 0925001 (2023)
Ultra-Short-Term Forecasting Method for Photovoltaic Power Based on Singular Spectrum Decomposition and Double Attention Mechanism
Xue Dong, Shengxiao Zhao, Yanyan Lu, Xiaofeng Chen, Yan Zhao, and Lei Liu
Accurate forecasting of photovoltaic power can effectively promote safe and efficient generation and utilization of photovoltaic power. Accordingly, an ultra-short-term photovoltaic power prediction method combining singular spectrum decomposition (SSD), double-attention mechanism, and bidirectional gating logic unit (BiGRU) time-series modeling is proposed to address the insufficient forecasting accuracy of existing methods. First, SSD is used to reduce the randomness and volatility of photovoltaic signals. A BiGRU network is then adopted to model the time series of the decomposed signals. Additionally, an attention module is designed to simultaneously learn the importance (weight) of the feature and time series by weighting the features extracted by the BiGRU network. The final forecast of photovoltaic power is obtained via the decision-making layer. The experimental results demonstrate that the SSD and attention mechanism can improve the accuracy of forecasts obtained from the deep time-series model. The proposed method is superior to several other conventional methods and is highly practical for different seasons and weather conditions. Accurate forecasting of photovoltaic power can effectively promote safe and efficient generation and utilization of photovoltaic power. Accordingly, an ultra-short-term photovoltaic power prediction method combining singular spectrum decomposition (SSD), double-attention mechanism, and bidirectional gating logic unit (BiGRU) time-series modeling is proposed to address the insufficient forecasting accuracy of existing methods. First, SSD is used to reduce the randomness and volatility of photovoltaic signals. A BiGRU network is then adopted to model the time series of the decomposed signals. Additionally, an attention module is designed to simultaneously learn the importance (weight) of the feature and time series by weighting the features extracted by the BiGRU network. The final forecast of photovoltaic power is obtained via the decision-making layer. The experimental results demonstrate that the SSD and attention mechanism can improve the accuracy of forecasts obtained from the deep time-series model. The proposed method is superior to several other conventional methods and is highly practical for different seasons and weather conditions.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2023
- Vol. 60, Issue 5, 0525001 (2023)
Properties of Surface Plasmon Coupling Based on Far-Field Spectroscopy
Baiyi Chen, Qifen Zhu, Na Gao, Penggang Li, Kai Huang, Yaping Wu, and Junyong Kang
In this work, we fabricate silver nanoparticle arrays with a small size, high density, and controllable surface densities in a specific range using a rapid thermal annealing method. Based on the far-field optical reflection and transmission spectra of the silver nanoparticle arrays that are experimentally measured and according to a theoretical numerical conversion, the absorption, scattering, and extinction properties of the silver nanoparticle arrays are investigated. The results show that the resonance wavelength derived from the localized surface plasmon tends to redshift with an increase in surface density of the silver nanoparticle arrays (i.e., decreased nanoparticle spacing). In addition, the redshift is more pronounced for stronger coupling interactions between neighboring nanoparticles. This method provides a helpful reference for analyzing localized surface plasmon properties, primarily for small high-density metal nanoparticle arrays with non-negligible inter-particle coupling interactions. In this work, we fabricate silver nanoparticle arrays with a small size, high density, and controllable surface densities in a specific range using a rapid thermal annealing method. Based on the far-field optical reflection and transmission spectra of the silver nanoparticle arrays that are experimentally measured and according to a theoretical numerical conversion, the absorption, scattering, and extinction properties of the silver nanoparticle arrays are investigated. The results show that the resonance wavelength derived from the localized surface plasmon tends to redshift with an increase in surface density of the silver nanoparticle arrays (i.e., decreased nanoparticle spacing). In addition, the redshift is more pronounced for stronger coupling interactions between neighboring nanoparticles. This method provides a helpful reference for analyzing localized surface plasmon properties, primarily for small high-density metal nanoparticle arrays with non-negligible inter-particle coupling interactions.
Laser & Optoelectronics Progress
- Publication Date: Dec. 10, 2023
- Vol. 60, Issue 23, 2325001 (2023)
Simulation and Analysis of Extinction Properties of Rh Nanostructures
Rui Jiang, Fang Chen, Zhaohui Zheng, Shaoying Ke, Jinrong Zhou, Guanzhou Liu, and Zhiwei Huang
Recently, Rh nanostructures have attracted significant research attention because of their strong localized surface plasmon resonance (LSPR) at ultraviolet wavelengths and stable physical and chemical properties. In this study, the extinction properties and electric field intensity distribution of cylindrical Rh nanostructures in 200?400 nm wavebands are systematically simulated and analyzed using the finite-difference time-domain method to examine the LSPR of Rh nanostructures. The results show that the LSPR properties of Rh nanostructures are significantly correlated with the diameter, height, spacing, and peripheral refractive index. The LSPR resonance wavebands of Rh nanostructures can be effectively modulated by varying the structural parameters. This study provides a reference for applying the LSPR of Rh nanostructures in areas such as ultraviolet absorption and optical detectors. Recently, Rh nanostructures have attracted significant research attention because of their strong localized surface plasmon resonance (LSPR) at ultraviolet wavelengths and stable physical and chemical properties. In this study, the extinction properties and electric field intensity distribution of cylindrical Rh nanostructures in 200?400 nm wavebands are systematically simulated and analyzed using the finite-difference time-domain method to examine the LSPR of Rh nanostructures. The results show that the LSPR properties of Rh nanostructures are significantly correlated with the diameter, height, spacing, and peripheral refractive index. The LSPR resonance wavebands of Rh nanostructures can be effectively modulated by varying the structural parameters. This study provides a reference for applying the LSPR of Rh nanostructures in areas such as ultraviolet absorption and optical detectors.
Laser & Optoelectronics Progress
- Publication Date: Oct. 10, 2023
- Vol. 60, Issue 19, 1925001 (2023)
Analysis of On-Orbit Performance of Solar Cells for Sun Vector Determination
Xiwang Xia, Han Du, and Keke Zhang
Solar cells can be used as coarse sun sensors, and sun vectors can be determined for the entire sky by combining several coarse sun sensors of the same specification. The accuracy of the sun vector is determined based on the on-orbit performance of the coarse sun sensors. On the basis of a large amount of on-orbit data of TZ-1 (TianZhi-1) satellite over an extended period, this study analyzed the angle error between sun vectors determined using coarse sun sensors and differential sun sensor. The output of the coarse sensors was inverted, and the installation angle error and performance attenuation of the coarse sensors were analyzed. The Kelly cosine curve corresponding to the triple junction GaAs solar cell was fitted by combining the output of the multiple coarse sensors. The analysis results show that the installation error of the coarse sensor is slight, the obtained sun vector error is smaller than 5°, and the performance attenuation rate is approximately 0.0621 V/a. The proposed sensor can achieve the all-sky acquisition of the sun vector within a specific accuracy range. Solar cells can be used as coarse sun sensors, and sun vectors can be determined for the entire sky by combining several coarse sun sensors of the same specification. The accuracy of the sun vector is determined based on the on-orbit performance of the coarse sun sensors. On the basis of a large amount of on-orbit data of TZ-1 (TianZhi-1) satellite over an extended period, this study analyzed the angle error between sun vectors determined using coarse sun sensors and differential sun sensor. The output of the coarse sensors was inverted, and the installation angle error and performance attenuation of the coarse sensors were analyzed. The Kelly cosine curve corresponding to the triple junction GaAs solar cell was fitted by combining the output of the multiple coarse sensors. The analysis results show that the installation error of the coarse sensor is slight, the obtained sun vector error is smaller than 5°, and the performance attenuation rate is approximately 0.0621 V/a. The proposed sensor can achieve the all-sky acquisition of the sun vector within a specific accuracy range.
Laser & Optoelectronics Progress
- Publication Date: Sep. 10, 2023
- Vol. 60, Issue 17, 1725001 (2023)
Light Source Homogenization Method for Large-Area LED Array Based on Microlens Array
Juan Nie, Jialin Du, Fanxing Li, Simo Wang, Fan Yang, Qingrong Chen, Bo Qi, and Wei Yan
LED array light sources are widely used in medicine, micro-nano processing, optical imaging, and other fields due to their high brightness, long life, energy savings, and environmental protection. However, their homogenization system has issues such as difficult light collimation and small achievable illumination spot area, making them difficult to be widely used in the optical field that requires uniform illumination. To address this issue, this paper proposes a microlens array based large-area LED array light source homogenization method. First, the theoretical analysis is performed by matrix optics and near-axis optics theory, and then the system design and simulation experiments are conducted by using light tools software. Finally, a large-area of the uniform spot is achieved on the image surface.Compared with the previous homogenization system, which can achieve up to 50 mm×50 mm, the homogenization system can achieve a uniform spot of 104 mm×104 mm, and uniformity of 87.375% of the large-area rule. This method is of great significance systems that require large-area uniform illumination in the fields of medicine, infrared night vision, projection display, and aerial lighting. LED array light sources are widely used in medicine, micro-nano processing, optical imaging, and other fields due to their high brightness, long life, energy savings, and environmental protection. However, their homogenization system has issues such as difficult light collimation and small achievable illumination spot area, making them difficult to be widely used in the optical field that requires uniform illumination. To address this issue, this paper proposes a microlens array based large-area LED array light source homogenization method. First, the theoretical analysis is performed by matrix optics and near-axis optics theory, and then the system design and simulation experiments are conducted by using light tools software. Finally, a large-area of the uniform spot is achieved on the image surface.Compared with the previous homogenization system, which can achieve up to 50 mm×50 mm, the homogenization system can achieve a uniform spot of 104 mm×104 mm, and uniformity of 87.375% of the large-area rule. This method is of great significance systems that require large-area uniform illumination in the fields of medicine, infrared night vision, projection display, and aerial lighting.
Laser & Optoelectronics Progress
- Publication Date: Aug. 10, 2023
- Vol. 60, Issue 15, 1525003 (2023)
Photonic-Plasmonic Hybrid Microcavity with Ultra-High Quality Factor Regulated by Bowtie Plasmonic Nanoantenna
Na Ma, Ping Jiang, Nianqi Kuang, Songze Li, and Xianfeng Xu
Ultra-high quality factor optical microcavities are key components for constructing various integrated photonic devices. Hybrid microcavities based on the photonic crystal microcavities provide a novel platform for realizing a strong light-matter interaction that possesses extensive application prospects in many fields, including cavity quantum electrodynamics, integrated single photon sources, and quantum computing. In this paper, we theoretically propose a novel photonic-plasmonic hybrid microcavity functioning in the visible light band based on the basic double heterostructure photonic crystal cavity with a gold bowtie plasmonic nanoantenna. Here, the structural parameters of the bowtie plasmonic nanostructures (i.e., gap, angle, length, thickness, and relative position) were adjusted to investigate the regulation effects on the quality factor Q, effective mode volume V, and figure of merit Q/V of the cavity using a three-dimensional finite-difference time-domain method. The simulation results reveal that the effective mode volume and the figure of merit of the hybrid microcavity are stable on the order of 10-6 (λ/n)3 and 108 (λ/n)-3, respectively. Moreover, we achieved the highest Q/V value of 5.730689×108 (λ/n)-3, depicting a value much better than that of other microcavities. Ultra-high quality factor optical microcavities are key components for constructing various integrated photonic devices. Hybrid microcavities based on the photonic crystal microcavities provide a novel platform for realizing a strong light-matter interaction that possesses extensive application prospects in many fields, including cavity quantum electrodynamics, integrated single photon sources, and quantum computing. In this paper, we theoretically propose a novel photonic-plasmonic hybrid microcavity functioning in the visible light band based on the basic double heterostructure photonic crystal cavity with a gold bowtie plasmonic nanoantenna. Here, the structural parameters of the bowtie plasmonic nanostructures (i.e., gap, angle, length, thickness, and relative position) were adjusted to investigate the regulation effects on the quality factor Q, effective mode volume V, and figure of merit Q/V of the cavity using a three-dimensional finite-difference time-domain method. The simulation results reveal that the effective mode volume and the figure of merit of the hybrid microcavity are stable on the order of 10-6 (λ/n)3 and 108 (λ/n)-3, respectively. Moreover, we achieved the highest Q/V value of 5.730689×108 (λ/n)-3, depicting a value much better than that of other microcavities.
Laser & Optoelectronics Progress
- Publication Date: Aug. 10, 2023
- Vol. 60, Issue 15, 1525002 (2023)
Performance Enhancement of Algan-Based Deep Ultraviolet Laser Diodes with Step Superlattice Electron Blocking Layer and Wedge-Shaped Hole Blocking Layer
Aoxiang Zhang, Bingyang Ren, Fang Wang, Juin. J. Liou, and Yuhuai Liu
The step superlattice (SSL) electron blocking layer (EBL) and wedge-shaped (WS) hole blocking layer (HBL) are proposed to improve the carrier injection efficiency, and optimize the performance of the deep ultraviolet laser diodes (DUV LDs). The Crosslight software is used to simulate the DUV LDs with rectangular EBL and HBL, rectangular superlattice (RSL) EBL and tower-shaped (TS) HBL, and SSL EBL and WS HBL, respectively. The simulation results indicate that SSL EBL and WS HBL increase the carrier injection in the quantum wells (QWs), reduce the carrier leakage in the non-active regions, increase radiation recombination rate, reduce the threshold voltage and threshold current, and increase the output power and the electro-optical conversion efficiency of DUV LDs more effectively. The step superlattice (SSL) electron blocking layer (EBL) and wedge-shaped (WS) hole blocking layer (HBL) are proposed to improve the carrier injection efficiency, and optimize the performance of the deep ultraviolet laser diodes (DUV LDs). The Crosslight software is used to simulate the DUV LDs with rectangular EBL and HBL, rectangular superlattice (RSL) EBL and tower-shaped (TS) HBL, and SSL EBL and WS HBL, respectively. The simulation results indicate that SSL EBL and WS HBL increase the carrier injection in the quantum wells (QWs), reduce the carrier leakage in the non-active regions, increase radiation recombination rate, reduce the threshold voltage and threshold current, and increase the output power and the electro-optical conversion efficiency of DUV LDs more effectively.
Laser & Optoelectronics Progress
- Publication Date: Aug. 10, 2023
- Vol. 60, Issue 15, 1525001 (2023)
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