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Microwave Photonics|35 Article(s)
Target position estimation using frequency-hopping signals based on microwave photonic subsampling
Xiaohu Tang, Cong Ma, Kunlin Shao, Yuxiang Cai, Ping Li, Yamei Zhang, and Shilong Pan
A microwave photonic subsampling digital receiver (MPSDR) is proposed and experimentally demonstrated for target detection with a sampling rate of 10 MSa/s. Stepped and pseudo-random frequency-hopping signals with frequencies across the K band are both used for target detection and can be captured by the MPSDR. The range profiles of the targets are then derived using a compressed sensing algorithm, and precise target position estimation is achieved by changing the measurement position of the antenna pair. The results demonstrate that the estimation accuracy remains comparable even when the pseudo-random frequency-hopping signal utilizes only 12.5% of the frequency points required by the stepped frequency-hopping signal. This highlights the efficiency and potential of the proposed MPSDR in processing complex signals while maintaining high accuracy. A microwave photonic subsampling digital receiver (MPSDR) is proposed and experimentally demonstrated for target detection with a sampling rate of 10 MSa/s. Stepped and pseudo-random frequency-hopping signals with frequencies across the K band are both used for target detection and can be captured by the MPSDR. The range profiles of the targets are then derived using a compressed sensing algorithm, and precise target position estimation is achieved by changing the measurement position of the antenna pair. The results demonstrate that the estimation accuracy remains comparable even when the pseudo-random frequency-hopping signal utilizes only 12.5% of the frequency points required by the stepped frequency-hopping signal. This highlights the efficiency and potential of the proposed MPSDR in processing complex signals while maintaining high accuracy.
Chinese Optics Letters
- Publication Date: Jun. 05, 2025
- Vol. 23, Issue 7, 073902 (2025)
Improving accuracy through double acousto-optic modulators in photonics-assisted mmWave heterodyne interferometric sensing
Yiwen Lu, Tong Yang, Qizhuang Cen, Xinpeng Wang, Chong Liu, Feifei Yin, Kun Xu, Ming Li, and Yitang Dai
The acousto-optic modulator (AOM) plays an important role in heterodyne interferometric sensing, and it is always regarded as an ideal optical frequency shifter. In this paper, we compare the effects of its residual zero-order diffraction in different AOM configurations. The theory shows that using double AOMs can effectively solve the same frequency crosstalk problem caused by zero-order perturbation without worsening the noise floor. The interferometer employs a photonics-assisted mmWave composed of two comb lines from an electro-optical frequency comb as the optical source, which results in the laser frequency noise cancellation in the difference. Experimentally, a dither with a peak-to-peak value of 0.15 ps in the single AOM configuration can be effectively suppressed to below the noise floor through double AOMs, which shows the potential to achieve high sensing accuracy. The acousto-optic modulator (AOM) plays an important role in heterodyne interferometric sensing, and it is always regarded as an ideal optical frequency shifter. In this paper, we compare the effects of its residual zero-order diffraction in different AOM configurations. The theory shows that using double AOMs can effectively solve the same frequency crosstalk problem caused by zero-order perturbation without worsening the noise floor. The interferometer employs a photonics-assisted mmWave composed of two comb lines from an electro-optical frequency comb as the optical source, which results in the laser frequency noise cancellation in the difference. Experimentally, a dither with a peak-to-peak value of 0.15 ps in the single AOM configuration can be effectively suppressed to below the noise floor through double AOMs, which shows the potential to achieve high sensing accuracy.
Chinese Optics Letters
- Publication Date: Jun. 04, 2025
- Vol. 23, Issue 7, 073901 (2025)
Photonics-enabled broadband continuous-wave terahertz computed tomography
Zuomin Yang, Lu Zhang, Zhidong Lü, Xing Fang, and Xianbin Yu
In this paper, we propose a photonic terahertz (THz) continuous-wave computed tomography (CT) system employing an optical frequency comb and specialized imaging algorithms. Our work leverages the system to offer unique advantages in detecting and analyzing samples that are challenging for traditional 2D scanning systems. Our experimental results, operating at 330 GHz, reach an exceptionally low amplitude standard deviation of 0.016 mV. Additionally, the proposed system performs nondestructive CT detection with a 0.5 mm error margin and obtains enhanced image quality, showing its great promise for implementing THz-CT imaging with high robustness and resolution. In this paper, we propose a photonic terahertz (THz) continuous-wave computed tomography (CT) system employing an optical frequency comb and specialized imaging algorithms. Our work leverages the system to offer unique advantages in detecting and analyzing samples that are challenging for traditional 2D scanning systems. Our experimental results, operating at 330 GHz, reach an exceptionally low amplitude standard deviation of 0.016 mV. Additionally, the proposed system performs nondestructive CT detection with a 0.5 mm error margin and obtains enhanced image quality, showing its great promise for implementing THz-CT imaging with high robustness and resolution.
Chinese Optics Letters
- Publication Date: May. 16, 2025
- Vol. 23, Issue 6, 063901 (2025)
Demonstration of 123.72-Gbps D-band fiber–THz–fiber system based on full photonic conversion technology with broadband optoelectronic devices
Yaxuan Li, Yuxin Tian, Boyu Dong, Yinjun Liu, Zhe Feng, Junwen Zhang, Bing Xiong, Nan Chi, and Yi Luo
We demonstrated a fiber–terahertz (THz)–fiber communication system at the D-band based on full photonic conversions, exploiting a modified unitraveling-carrier photodiode (MUTC-PD) module to achieve optical-to-THz conversion at the transmitter end and an ultrabroadband packaged thin-film lithium niobate Mach–Zehnder modulator (MZM) to convert the THz signal to the optical signal at the receiver end. This system successfully realized the transmission of 33-Gbaud 16-quadrature amplitude modulation (QAM) and 31-Gbaud probabilistic shaping-64-QAM signals through 10-km standard single-mode fiber (SSMF), 0.6-m wireless distance, and the subsequent 5-km SSMF, achieving net data rates of 116.03 and 123.72 Gbps, respectively. We demonstrated a fiber–terahertz (THz)–fiber communication system at the D-band based on full photonic conversions, exploiting a modified unitraveling-carrier photodiode (MUTC-PD) module to achieve optical-to-THz conversion at the transmitter end and an ultrabroadband packaged thin-film lithium niobate Mach–Zehnder modulator (MZM) to convert the THz signal to the optical signal at the receiver end. This system successfully realized the transmission of 33-Gbaud 16-quadrature amplitude modulation (QAM) and 31-Gbaud probabilistic shaping-64-QAM signals through 10-km standard single-mode fiber (SSMF), 0.6-m wireless distance, and the subsequent 5-km SSMF, achieving net data rates of 116.03 and 123.72 Gbps, respectively.
Chinese Optics Letters
- Publication Date: May. 06, 2025
- Vol. 23, Issue 5, 053901 (2025)
Automatic phase-matching technique for cascaded electro-optic frequency combs|Editors' Pick
Jin Wang, Feifei Yin, Zikai Yin, Zheng Wang, Haoyan Xu, Yitang Dai, and Kun Xu
We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electro-optic modulators. By analyzing the power changes of different spectral lines, our method enables real-time monitoring and dynamic adjustment to achieve precise phase matching. Experiments have confirmed the fast phase matching and the adjustable spacing of a flat electro-optic frequency comb and its long-term stability. This method provides flexible and efficient light source solutions for optical communications, spectral analysis, and optical measurements. We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electro-optic modulators. By analyzing the power changes of different spectral lines, our method enables real-time monitoring and dynamic adjustment to achieve precise phase matching. Experiments have confirmed the fast phase matching and the adjustable spacing of a flat electro-optic frequency comb and its long-term stability. This method provides flexible and efficient light source solutions for optical communications, spectral analysis, and optical measurements.
Chinese Optics Letters
- Publication Date: Jan. 27, 2025
- Vol. 23, Issue 1, 013901 (2025)
Optical multipath self-interference cancellation for a wideband in-band full-duplex system using a silicon photonic modulator chip
Xiao Yu, Jia Ye, Lianshan Yan, Tao Zhou, Yue Zhu, Peng Li, Xihua Zou, and Wei Pan
We propose and experimentally demonstrate a photonic method for wideband multipath self-interference cancellation using a silicon photonic modulator chip. The chip generates phase-inverted reference signals by leveraging the opposite phase between optical sidebands. Effectively managing amplitude and phase imbalances between self-interference and reference signals, the approach rectifies discrepancies through consistent chip manufacturing and packaging processes. Employing photonic multi-dimensional multiplexing, including wavelength and polarization, enables the acquisition of multiple reference signals. Experimental results show multipath cancellation depths of 25.53 dB and 23.81 dB for bandwidths of 500 MHz and 1 GHz, achieved by superimposing 2-path reference signals. We propose and experimentally demonstrate a photonic method for wideband multipath self-interference cancellation using a silicon photonic modulator chip. The chip generates phase-inverted reference signals by leveraging the opposite phase between optical sidebands. Effectively managing amplitude and phase imbalances between self-interference and reference signals, the approach rectifies discrepancies through consistent chip manufacturing and packaging processes. Employing photonic multi-dimensional multiplexing, including wavelength and polarization, enables the acquisition of multiple reference signals. Experimental results show multipath cancellation depths of 25.53 dB and 23.81 dB for bandwidths of 500 MHz and 1 GHz, achieved by superimposing 2-path reference signals.
Chinese Optics Letters
- Publication Date: Jul. 05, 2024
- Vol. 22, Issue 7, 073901 (2024)
Photonics-assisted joint radar jamming and secure communication in the millimeter-wave band based on CE-LFM-OFDM
Dongju Du, Yanyi Wang, Yingxiong Song, Nan Ye, Zhengxuan Li, Qianwu Zhang, Junjie Zhang, Jian Chen, Bingyao Cao, and Jianjun Yu
This paper reports a photonics-assisted millimeter-wave (mm-wave) joint radar jamming and secure communication system constructed through a photonic upconversion technique. In the experiments, a 30 GHz constant envelope linear frequency-modulated orthogonal frequency division modulation (CE-LFM-OFDM) signal with an instantaneous bandwidth of 1 GHz is synthesized by encoding 1 GBaud encrypted 16-quadrature amplitude modulation (16-QAM) OFDM signal. The velocity deception jamming is achieved with a spurious suppression ratio over 30 dB. Furthermore, we efficiently execute range deception jamming with a time shift of 10 ns. Simultaneously, the encrypted 16-QAM OFDM signal is successfully transmitted over a 1.2 m wireless link, with a data rate of 4 Gbit/s. This paper reports a photonics-assisted millimeter-wave (mm-wave) joint radar jamming and secure communication system constructed through a photonic upconversion technique. In the experiments, a 30 GHz constant envelope linear frequency-modulated orthogonal frequency division modulation (CE-LFM-OFDM) signal with an instantaneous bandwidth of 1 GHz is synthesized by encoding 1 GBaud encrypted 16-quadrature amplitude modulation (16-QAM) OFDM signal. The velocity deception jamming is achieved with a spurious suppression ratio over 30 dB. Furthermore, we efficiently execute range deception jamming with a time shift of 10 ns. Simultaneously, the encrypted 16-QAM OFDM signal is successfully transmitted over a 1.2 m wireless link, with a data rate of 4 Gbit/s.
Chinese Optics Letters
- Publication Date: Jun. 20, 2024
- Vol. 22, Issue 6, 063902 (2024)
High-efficiency and flexible photonic microwave harmonic down-converter based on self-oscillation optical frequency combs
Xin Zhang, Tao Pu, Huatao Zhu, Yunshan Zhang, Gengze Wu, Jin Li, and Jilin Zheng
Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this paper, a high-efficiency and flexible PMHDC is proposed and demonstrated. The properties of the OFC, such as the carrier-to-noise ratio (CNR), bandwidth and free spectral range (FSR), and the influence of optical injection, are investigated. The broadband OFC provides a frequency tunable and high-quality local oscillation (LO), which guarantees flexible down-conversion for the radio frequency (RF) signal. The sideband selective amplification (SSA) effect not only improves the conversion efficiency but also promotes single-sideband modulation. The conversion range can reach 100 GHz. The 12–40 GHz RF signal can be down-converted to intermediate frequency (IF) signals with a high conversion efficiency of 14.9 dB. The fixed 40-GHz RF signal is flexibly down-converted to an IF signal with the frequency from 55.4 to 2129.4 MHz. The phase noise of an IF signal at a frequency offset of 10 kHz is the same as that of the input RF signal. The PMHDC shows great performance and will find applications in radio-over-fiber (RoF) networks, electronic warfare receivers, avionics, and wireless communication systems. Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this paper, a high-efficiency and flexible PMHDC is proposed and demonstrated. The properties of the OFC, such as the carrier-to-noise ratio (CNR), bandwidth and free spectral range (FSR), and the influence of optical injection, are investigated. The broadband OFC provides a frequency tunable and high-quality local oscillation (LO), which guarantees flexible down-conversion for the radio frequency (RF) signal. The sideband selective amplification (SSA) effect not only improves the conversion efficiency but also promotes single-sideband modulation. The conversion range can reach 100 GHz. The 12–40 GHz RF signal can be down-converted to intermediate frequency (IF) signals with a high conversion efficiency of 14.9 dB. The fixed 40-GHz RF signal is flexibly down-converted to an IF signal with the frequency from 55.4 to 2129.4 MHz. The phase noise of an IF signal at a frequency offset of 10 kHz is the same as that of the input RF signal. The PMHDC shows great performance and will find applications in radio-over-fiber (RoF) networks, electronic warfare receivers, avionics, and wireless communication systems.
Chinese Optics Letters
- Publication Date: Jun. 13, 2024
- Vol. 22, Issue 6, 063901 (2024)
Stability-enhanced RF signal transmission over long fiber-optic links
Zhiqian Yin, Manhang Zheng, Chuanbo Zhang, Shijian Guan, Xin Zhou, Yitong Liu, Zeyu Gang, Jiaqiang Nie, Yunshan Zhang, Xingbang Zhu, Tao Fang, and Xiangfei Chen
We propose a method for optimizing the phase stability of microwave signal transmission over long distances. First, the design of the photon link was modified to reduce the radio frequency (RF) signal’s baseline noise and increase power. Second, a low-noise driver circuit was developed for a two-section distributed feedback (DFB) laser designed using reconstruction equivalent chirp (REC) technology to create an ultra-stable laser, and its performance was characterized through linewidth data. Test results indicate that the DFB laser achieved narrower linewidth, improving system phase stability. When an injection current (30 mA) is applied to the reflection section of the two-section DFB laser, the laser linewidth will be narrower (1.38 MHz), further enhancing the system’s phase transmission stability. At a 1 Hz offset frequency, a residual phase noise of -88.65 dBc/Hz is obtained. The short-term stability with an averaging time of 1 s is 1.60 × 10-14, and the long-term stability over a testing time of 60,000 s is 3.41 × 10-18. Even after incorporating temperature variations, the long-term stability reaches 8.37 × 10-18 at 22 h. We propose a method for optimizing the phase stability of microwave signal transmission over long distances. First, the design of the photon link was modified to reduce the radio frequency (RF) signal’s baseline noise and increase power. Second, a low-noise driver circuit was developed for a two-section distributed feedback (DFB) laser designed using reconstruction equivalent chirp (REC) technology to create an ultra-stable laser, and its performance was characterized through linewidth data. Test results indicate that the DFB laser achieved narrower linewidth, improving system phase stability. When an injection current (30 mA) is applied to the reflection section of the two-section DFB laser, the laser linewidth will be narrower (1.38 MHz), further enhancing the system’s phase transmission stability. At a 1 Hz offset frequency, a residual phase noise of -88.65 dBc/Hz is obtained. The short-term stability with an averaging time of 1 s is 1.60 × 10-14, and the long-term stability over a testing time of 60,000 s is 3.41 × 10-18. Even after incorporating temperature variations, the long-term stability reaches 8.37 × 10-18 at 22 h.
Chinese Optics Letters
- Publication Date: May. 14, 2024
- Vol. 22, Issue 5, 053901 (2024)
Optical pulse repetition rate division using an optoelectronic oscillator
Ping Li, Kunlin Shao, Yamei Zhang, and Shilong Pan
An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed. An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.
Chinese Optics Letters
- Publication Date: Apr. 25, 2024
- Vol. 22, Issue 4, 043902 (2024)
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