Design of Pattern Reconfigurable Microstrip Array Antenna in Terahertz Band
Ying Wang, Chunshu Li, and Xiang Yan
A graphene-based reconfigurable microstrip array antenna suitable for the terahertz band was designed in this study. The design combined the unique advantages of grapheme for impedance matching and electrical controllability in the terahertz band and the characteristics of high radiation efficiency of the reconfigurable microstrip array antenna. The array antenna unit embedded a graphene patch in the radiant patch as a switch and changed the switch's on-off and off-off states by adjusting the applied bias voltage of graphene. The antenna unit and the array antenna have an operating frequency of 5.012 THz. The antenna unit exhibits strong gain characteristics and anti-interference performance, and can realize the pattern of adjustment to 12°?24° at the working frequency. The 2×2 microstrip array antenna composed of the antenna unit can realize the pattern reconfiguration function of 0°?13°. The simulation results show that the maximum gain of the array antenna is 12.5 dBi and the maximum beam width is 51.4°. In addition, the array antenna exhibits good directivity and anti-interference ability.A graphene-based reconfigurable microstrip array antenna suitable for the terahertz band was designed in this study. The design combined the unique advantages of grapheme for impedance matching and electrical controllability in the terahertz band and the characteristics of high radiation efficiency of the reconfigurable microstrip array antenna. The array antenna unit embedded a graphene patch in the radiant patch as a switch and changed the switch's on-off and off-off states by adjusting the applied bias voltage of graphene. The antenna unit and the array antenna have an operating frequency of 5.012 THz. The antenna unit exhibits strong gain characteristics and anti-interference performance, and can realize the pattern of adjustment to 12°?24° at the working frequency. The 2×2 microstrip array antenna composed of the antenna unit can realize the pattern reconfiguration function of 0°?13°. The simulation results show that the maximum gain of the array antenna is 12.5 dBi and the maximum beam width is 51.4°. In addition, the array antenna exhibits good directivity and anti-interference ability.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906002 (2024)
- DOI：10.3788/LOP231190
Vortex Mode Amplification Based on Ring-Core Fiber Doped with PbSe Quantum Dots
Hengfei Guo, Huimei Wei, Na Chen, Yanhua Dong, Jianxiang Wen, Yana Shang, Zhenyi Chen, and Fufei Pang
The PbSe quantum dot-doped ring-core fiber is successfully prepared using a modified chemical vapor deposition method. The fiber has a double-clad structure, with a refractive index difference of approximately 2.2% between the ring core and the inner cladding. The types and contents of elements in the fiber are verified via electron probe microanalysis. The crystal structure of PbSe quantum dots is examined using a high-resolution transmission electron microscope, and the Raman spectrum is measured. The results proved that PbSe quantum dots were doped successfully into the ring-core fiber. This provides an important reference value for preparing semiconductor quantum dot-doped fiber. The PbSe quantum dot-doped ring-core fiber is the foundation for the vortex mode amplification system. The first- to third-order vortex amplifying modes are realized at 1550 nm. When the pump power is 634 mW, the on-off gains of all modes are greater than 13 dB, and the differential mode gains are less than 2.45 dB. This experimental system is expected to promote further research on vortex mode broadband amplification.The PbSe quantum dot-doped ring-core fiber is successfully prepared using a modified chemical vapor deposition method. The fiber has a double-clad structure, with a refractive index difference of approximately 2.2% between the ring core and the inner cladding. The types and contents of elements in the fiber are verified via electron probe microanalysis. The crystal structure of PbSe quantum dots is examined using a high-resolution transmission electron microscope, and the Raman spectrum is measured. The results proved that PbSe quantum dots were doped successfully into the ring-core fiber. This provides an important reference value for preparing semiconductor quantum dot-doped fiber. The PbSe quantum dot-doped ring-core fiber is the foundation for the vortex mode amplification system. The first- to third-order vortex amplifying modes are realized at 1550 nm. When the pump power is 634 mW, the on-off gains of all modes are greater than 13 dB, and the differential mode gains are less than 2.45 dB. This experimental system is expected to promote further research on vortex mode broadband amplification.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906001 (2024)
- DOI：10.3788/LOP231164
First Arrival Time Pickup Method of Vibration Signals for Distributed Acoustic Sensing Systems
Liang Huang, Lei Liang, Ke Jiang, and Shangming Du
Two-dimensional (2D) spatial position of a vibration source in an optical distributed acoustic sensing (DAS) system can be determined based on a phase-sensitive optical time-domain reflectometer. However, due to interference and noise, this approach may acquire inaccurate arrival time information of the first arrival wave of the vibration source at different positions of the optical cable, resulting in large positioning errors. In this study, we propose a method of estimating the first arrival wave of the vibration source in a DAS system based on bilateral filtered edge detection. First, the spatio-temporal 2D signals collected by the DAS system were converted into a gray-scale map, and then the bilateral filtering method was used to reduce the noise. The edge features in the gray-scale image were extracted using a Canny operator-based edge detection method to obtain the first arrival time of the source. The proposed method can simultaneously consider the overall temporal and spatial characteristics of spatio-temporal 2D data and improve the accuracy of low signal-to-noise ratio signal of first arrival time pickup. Results show that for low signal-to-noise ratio signals affected by interference and system noise, the average error for pickup arrival time does not exceed 3 ms, pickup accuracy is higher than that of the traditional method; the algorithm takes only 0.1 s on average, and pickup time consumption is low.Two-dimensional (2D) spatial position of a vibration source in an optical distributed acoustic sensing (DAS) system can be determined based on a phase-sensitive optical time-domain reflectometer. However, due to interference and noise, this approach may acquire inaccurate arrival time information of the first arrival wave of the vibration source at different positions of the optical cable, resulting in large positioning errors. In this study, we propose a method of estimating the first arrival wave of the vibration source in a DAS system based on bilateral filtered edge detection. First, the spatio-temporal 2D signals collected by the DAS system were converted into a gray-scale map, and then the bilateral filtering method was used to reduce the noise. The edge features in the gray-scale image were extracted using a Canny operator-based edge detection method to obtain the first arrival time of the source. The proposed method can simultaneously consider the overall temporal and spatial characteristics of spatio-temporal 2D data and improve the accuracy of low signal-to-noise ratio signal of first arrival time pickup. Results show that for low signal-to-noise ratio signals affected by interference and system noise, the average error for pickup arrival time does not exceed 3 ms, pickup accuracy is higher than that of the traditional method; the algorithm takes only 0.1 s on average, and pickup time consumption is low.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906009 (2024)
- DOI：10.3788/LOP223443
Preparation of panda-shaped photonic crystal fibers with and without silver wire
Junbo Lou, Yonghui Yang, Qiang Qu, and Shuguang Li
A method of preparing panda-shaped photonic crystal fibers (PCFs) based on secondary drawing technology is proposed in this paper. The secondary drawing can not only reduce fiber diameter but also reduce core size by adding a glass sleeve. Silver-filled and non-silver-filled panda PCFs are prepared. The two ends of silver-filled panda PCF are connected with a broadband light source and a spectrometer, respectively, and the surface plasmon resonance phenomenon is detected. The secondary drawing technology provides a meaningful reference for the preparation of PCF in the future, and the prepared silver-filled panda PCF can be prepared into an optical fiber filter.A method of preparing panda-shaped photonic crystal fibers (PCFs) based on secondary drawing technology is proposed in this paper. The secondary drawing can not only reduce fiber diameter but also reduce core size by adding a glass sleeve. Silver-filled and non-silver-filled panda PCFs are prepared. The two ends of silver-filled panda PCF are connected with a broadband light source and a spectrometer, respectively, and the surface plasmon resonance phenomenon is detected. The secondary drawing technology provides a meaningful reference for the preparation of PCF in the future, and the prepared silver-filled panda PCF can be prepared into an optical fiber filter.
- May. 08, 2024
- Chinese Optics Letters
- Vol. 22, Issue 5, 050603 (2024)
- DOI：10.3788/COL202422.050603
High-Sensitivity Liquid Level Sensor Based on Seven Core Fiber
Min Shao, Hanping Li, Xue Zhao, Dakuan Yu, and Xueguang Qiao
A liquid level sensor based on a single mode-peanut-seven core-peanut-single mode fiber structure is developed. The sensor uses the "peanut structure" as a fiber coupler to improve the coupling efficiency of the single-mode fiber and seven-core fiber. The first fiber "peanut structure" is used to excite the cladding mode, and the second fiber "peanut structure" couples the cladding mode with the core mode to produce interference. Because a phase difference between the cladding and core-based modes appears as they transmit through the seven-core fiber, when the liquid level of the environmental solution changes, the phase difference changes, eventually changing the transmission spectrum. In this study, the liquid level and temperature response characteristics of the sensors with seven-core fiber lengths of 24, 28, and 32 mm were experimentally studied. The experimental results show that with the increase of the liquid level, the transmission spectrum of the sensor shows a blue shift. The liquid level sensitivities of the three sensors are -0.4069, -0.2739, and -0.1653 nm/mm, and their liquid level measurement ranges are 24, 28, and 32 mm, respectively. In the water temperature range of 35?90 ℃, the transmission spectrum of the sensor shows a red shift with an increase in temperature. The temperature sensitivities of the three sensors are 0.0885, 0.0740, and 0.0879 nm/℃. The experiment shows that the sensor has the characteristics of high sensitivity, low cost, and simple fabrication, indicating that it has a good application prospect in the petrochemical industry and other fields.A liquid level sensor based on a single mode-peanut-seven core-peanut-single mode fiber structure is developed. The sensor uses the "peanut structure" as a fiber coupler to improve the coupling efficiency of the single-mode fiber and seven-core fiber. The first fiber "peanut structure" is used to excite the cladding mode, and the second fiber "peanut structure" couples the cladding mode with the core mode to produce interference. Because a phase difference between the cladding and core-based modes appears as they transmit through the seven-core fiber, when the liquid level of the environmental solution changes, the phase difference changes, eventually changing the transmission spectrum. In this study, the liquid level and temperature response characteristics of the sensors with seven-core fiber lengths of 24, 28, and 32 mm were experimentally studied. The experimental results show that with the increase of the liquid level, the transmission spectrum of the sensor shows a blue shift. The liquid level sensitivities of the three sensors are -0.4069, -0.2739, and -0.1653 nm/mm, and their liquid level measurement ranges are 24, 28, and 32 mm, respectively. In the water temperature range of 35?90 ℃, the transmission spectrum of the sensor shows a red shift with an increase in temperature. The temperature sensitivities of the three sensors are 0.0885, 0.0740, and 0.0879 nm/℃. The experiment shows that the sensor has the characteristics of high sensitivity, low cost, and simple fabrication, indicating that it has a good application prospect in the petrochemical industry and other fields.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906008 (2024)
- DOI：10.3788/LOP223168
Research on Φ-OTDR Perimeter Security Monitoring Based on GAF-HorNet
Sheng Hu, Xinmin Hu, Shasha Li, Lü Puchu, Haixin Qin, Can Zhao, Minghu Wu, and Cong Liu
Phase-sensitive optical time-domain reflection (Φ-OTDR) technology is a distributed fiber-optic sensing technique with the advantage of high-precision vibration monitoring. It can be used to detect disturbance events in the field of perimeter security. Traditional recognition methods require the manual extraction of vibration signal features and cannot retain a time correlation, leading to information loss. To solve this problem, a disturbance event recognition method based on GAF-HorNet, which does not require a feature extraction step, is developed. A one-dimensional vibration signal is converted into a two-dimensional image through a Gramian angular field (GAF), and HorNet is used to train the model and perform recognition and classification. To verify the performance of the algorithm, four classical algorithms are selected to train the model for comparative experiments. The experimental results demonstrate that the average accuracy of the proposed algorithm is 93.56% for six types of signal: background noise, stone knocking, stone stroking, branch stroking, pulling, and climbing. Compared with previous methods, the method proposed has better recognition rate and false alarm rate performances.Phase-sensitive optical time-domain reflection (Φ-OTDR) technology is a distributed fiber-optic sensing technique with the advantage of high-precision vibration monitoring. It can be used to detect disturbance events in the field of perimeter security. Traditional recognition methods require the manual extraction of vibration signal features and cannot retain a time correlation, leading to information loss. To solve this problem, a disturbance event recognition method based on GAF-HorNet, which does not require a feature extraction step, is developed. A one-dimensional vibration signal is converted into a two-dimensional image through a Gramian angular field (GAF), and HorNet is used to train the model and perform recognition and classification. To verify the performance of the algorithm, four classical algorithms are selected to train the model for comparative experiments. The experimental results demonstrate that the average accuracy of the proposed algorithm is 93.56% for six types of signal: background noise, stone knocking, stone stroking, branch stroking, pulling, and climbing. Compared with previous methods, the method proposed has better recognition rate and false alarm rate performances.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906005 (2024)
- DOI：10.3788/LOP231499
Damage Detection Method for Wind Turbine Blade Based on Optical Frequency Domain Reflectometry
Junchao Dong, Mingming Luo, Jianfei Liu, and Wenrong Yang
A new wind turbine blade damage detection method is proposed to address the challenges surrounding imprecise positioning and the inability to monitor the turbine under operating conditions, which is a shortcoming of traditional wind turbine blade damage detection. The proposed method uses optical frequency domain reflectometry(OFDR) to measure the surface strain of the wind turbine blade. Subsequently, fast Fourier transform is taken for the strain value and its fundamental frequency amplitude is taken to obtain the blade surface strain distribution. On this basis, the position, length and width of the blade damage are calculated. According to the relationship between the strain and damage degree, the damage degree judgment formula is fitted, and the blade damage degree is identified. Based on OFDR, a cantilever beam damage detection experiment is designed to simulate the instantaneous state of the cantilever beam vibration, and the damage location is identified according to the strain distribution, which verifies the feasibility of the proposed damage identification method.A new wind turbine blade damage detection method is proposed to address the challenges surrounding imprecise positioning and the inability to monitor the turbine under operating conditions, which is a shortcoming of traditional wind turbine blade damage detection. The proposed method uses optical frequency domain reflectometry(OFDR) to measure the surface strain of the wind turbine blade. Subsequently, fast Fourier transform is taken for the strain value and its fundamental frequency amplitude is taken to obtain the blade surface strain distribution. On this basis, the position, length and width of the blade damage are calculated. According to the relationship between the strain and damage degree, the damage degree judgment formula is fitted, and the blade damage degree is identified. Based on OFDR, a cantilever beam damage detection experiment is designed to simulate the instantaneous state of the cantilever beam vibration, and the damage location is identified according to the strain distribution, which verifies the feasibility of the proposed damage identification method.
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906004 (2024)
- DOI：10.3788/LOP231432
Coherent Optical Communication Speed Measurement Method Based on Modulated Code Element Doppler Frequency Measurement
Quan Zhang, Qingchen Xu, Xiong Hu, Xiaocheng Wu, and Junfeng Yang
High precision inter-satellite velocity measurement technology is one of the key technologies for realizing integration of satellite laser communication measurements and autonomous navigation. We propose an inter-satellite coherent optical communication link velocity measurement method based on modulated code element Doppler measurement. The method adopts a one-way unidirectional approach to obtain phase-continuous code element Doppler signals by using the phase and symbol information of code element symbol synchronization and verdict at the receiver side and by removing the phase modulation information in the baseband sampling data. This can aid in realizing the real-time high accuracy of satellite relative motion velocity while completing inter-satellite communication. The simulation results verify that this method can achieve the relative velocity measurement from 0 to 11.625 km/s at a communication rate of 1 Gbit/s and bit error rate (BER) of 10-9. Furthermore, the velocity measurement uncertainty exceeds 10.00 mm/s.High precision inter-satellite velocity measurement technology is one of the key technologies for realizing integration of satellite laser communication measurements and autonomous navigation. We propose an inter-satellite coherent optical communication link velocity measurement method based on modulated code element Doppler measurement. The method adopts a one-way unidirectional approach to obtain phase-continuous code element Doppler signals by using the phase and symbol information of code element symbol synchronization and verdict at the receiver side and by removing the phase modulation information in the baseband sampling data. This can aid in realizing the real-time high accuracy of satellite relative motion velocity while completing inter-satellite communication. The simulation results verify that this method can achieve the relative velocity measurement from 0 to 11.625 km/s at a communication rate of 1 Gbit/s and bit error rate (BER) of
- May. 10, 2024
- Laser & Optoelectronics Progress
- Vol. 61, Issue 9, 0906003 (2024)
- DOI：10.3788/LOP231276
High power cladding-pumped low quantum defect Raman fiber amplifier
Yang Zhang, Jiangming Xu, Junrui Liang, Sicheng Li, Jun Ye, Xiaoya Ma, Tianfu Yao, Zhiyong Pan, Jinyong Leng, and Pu Zhou
Heat generated by the quantum defect (QD) in optically pumped lasers can result in detrimental effects such as mode instability, frequency noise, and even catastrophic damage. Previously, we demonstrated that boson-peak-based Raman fiber lasers have great potential in low QD laser generation. But their power scalability and heat load characteristics have yet to be investigated. Here, we demonstrate a boson-peak-based Raman fiber amplifier (RFA) with 815 W output power and a QD of 1.3%. The low heat generation characteristics of this low QD RFA are demonstrated. Both experimental and simulation results show that at this power level, the heat load of the low QD RFA is significantly lower than that of the conventional RFA with a QD of 4.8%. Thanks to its low heat generation characteristics, the proposed phosphosilicate-fiber-based low QD RFA provides an effective solution for the intractable thermal issue in optically pumped lasers, which is of significance in reducing the laser’s noise, improving the laser’s stability and safety, and solving the challenge of heat removing.Heat generated by the quantum defect (QD) in optically pumped lasers can result in detrimental effects such as mode instability, frequency noise, and even catastrophic damage. Previously, we demonstrated that boson-peak-based Raman fiber lasers have great potential in low QD laser generation. But their power scalability and heat load characteristics have yet to be investigated. Here, we demonstrate a boson-peak-based Raman fiber amplifier (RFA) with 815 W output power and a QD of 1.3%. The low heat generation characteristics of this low QD RFA are demonstrated. Both experimental and simulation results show that at this power level, the heat load of the low QD RFA is significantly lower than that of the conventional RFA with a QD of 4.8%. Thanks to its low heat generation characteristics, the proposed phosphosilicate-fiber-based low QD RFA provides an effective solution for the intractable thermal issue in optically pumped lasers, which is of significance in reducing the laser’s noise, improving the laser’s stability and safety, and solving the challenge of heat removing.
- May. 01, 2024
- Photonics Research
- Vol. 12, Issue 5, 995 (2024)
- DOI：10.1364/PRJ.510057
High-security multi-constellation shaping modulation with asymmetric encryption
Lei Jiang, Bo Liu, Jianxin Ren, Xiangyu Wu, Rahat Ullah, Yaya Mao, Shuaidong Chen, Yilan Ma, Lilong Zhao, and Feng Tian
This Letter proposes a high-security modulation scheme for optical transmission systems. By using multi-constellation shaping and asymmetric encryption, the information security can be enhanced and quantum computer cracking can be effectively resisted. Three-dimensional (3D) carrier-less amplitude phase modulation is utilized to superposition and transmit 3D signals. Experimental verification is conducted using a seven-core weakly coupled fiber platform. The results demonstrate that the proposed scheme can effectively protect the system from any illegal attacker.This Letter proposes a high-security modulation scheme for optical transmission systems. By using multi-constellation shaping and asymmetric encryption, the information security can be enhanced and quantum computer cracking can be effectively resisted. Three-dimensional (3D) carrier-less amplitude phase modulation is utilized to superposition and transmit 3D signals. Experimental verification is conducted using a seven-core weakly coupled fiber platform. The results demonstrate that the proposed scheme can effectively protect the system from any illegal attacker.
- Apr. 26, 2024
- Chinese Optics Letters
- Vol. 22, Issue 4, 040602 (2024)
- DOI：10.3788/COL202422.040602
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