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Microwave Photonics|31 Article(s)
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)
Demonstration of radar-aided flexible communication in a photonics-based W-band distributed integrated sensing and communication system for 6G
Junlian Jia, Boyu Dong, Li Tao, Jianyang Shi, Nan Chi, and Junwen Zhang
This paper experimentally demonstrates a distributed photonics-based W-band integrated sensing and communication (ISAC) system, in which radar sensing can aid the communication links in alignment and data rate estimation. As a proof-of-concept, the ISAC system locates the users, guides the alignment, and sets a communication link with the estimated highest data rate. A peak net data rate of 68.6 Gbit/s and a target sensing with a less-than-1-cm error and a sub-2-cm resolution have been tested over a 10-km fiber and a 1.15-m free space transmission in the photonics-based W-band ISAC system. The achievable net data rates of the users at different locations estimated by sensing are experimentally verified. This paper experimentally demonstrates a distributed photonics-based W-band integrated sensing and communication (ISAC) system, in which radar sensing can aid the communication links in alignment and data rate estimation. As a proof-of-concept, the ISAC system locates the users, guides the alignment, and sets a communication link with the estimated highest data rate. A peak net data rate of 68.6 Gbit/s and a target sensing with a less-than-1-cm error and a sub-2-cm resolution have been tested over a 10-km fiber and a 1.15-m free space transmission in the photonics-based W-band ISAC system. The achievable net data rates of the users at different locations estimated by sensing are experimentally verified.
Chinese Optics Letters
- Publication Date: Apr. 17, 2024
- Vol. 22, Issue 4, 043901 (2024)
Highly efficient conversion from classical guided waves to topological chiral edge states|Editors' Pick
Jianfei Han, Feng Liang, Yulin Zhao, Xiao Ding, Xiangru Wang, Deshuang Zhao, and Bing-Zhong Wang
Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and defects. However, the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world applications. In this paper, a highly efficient conversion structure between a classical rectangular waveguide and a topological one-way waveguide is proposed and demonstrated at the microwave frequency, which efficiently converts classical guided waves to topological one-way edge states. A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge states. With the conversion structure, the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling efficiency, which can ensure high transmission of the whole system (i.e., from the source and the receiver). Simulation and measurement results demonstrate the proposed method. This investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems. Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and defects. However, the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world applications. In this paper, a highly efficient conversion structure between a classical rectangular waveguide and a topological one-way waveguide is proposed and demonstrated at the microwave frequency, which efficiently converts classical guided waves to topological one-way edge states. A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge states. With the conversion structure, the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling efficiency, which can ensure high transmission of the whole system (i.e., from the source and the receiver). Simulation and measurement results demonstrate the proposed method. This investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems.
Chinese Optics Letters
- Publication Date: Feb. 27, 2024
- Vol. 22, Issue 2, 023902 (2024)
Programmable photonic RF filters based on an integrated Fabry–Pérot laser with a saturable absorber
Zhenzhen Xu, Yitong Liu, Jiahui Liu, Ling Wang, Wentao Sun, Zhenxing Sun, and Xiangfei Chen
We propose and experimentally demonstrate the programmable photonic radio frequency (RF) filters based on an integrated Fabry–Pérot laser with a saturable absorber (FP-SA). Owing to the high output power and the relative flatness spectrum of the FP-SA laser, only a waveshaper and an erbium-doped fiber amplifier (EDFA) were needed, which can greatly reduce the complexity of the system. The sinc filter employed 87 taps, representing a record-high tap number and resulting in a 3-dB bandwidth of 0.27 GHz and a quality factor of 148. Furthermore, Gaussian apodization enabled the out-of-band rejection of the filter to reach 34 dB and the center frequency to be finely tuned over a wide range, spanning from 4 to 14 GHz. These results indicate that the proposed scheme could provide a promising guideline for the photonic RF filters that demand both high reconfigurability and greatly reduced size and complexity. We propose and experimentally demonstrate the programmable photonic radio frequency (RF) filters based on an integrated Fabry–Pérot laser with a saturable absorber (FP-SA). Owing to the high output power and the relative flatness spectrum of the FP-SA laser, only a waveshaper and an erbium-doped fiber amplifier (EDFA) were needed, which can greatly reduce the complexity of the system. The sinc filter employed 87 taps, representing a record-high tap number and resulting in a 3-dB bandwidth of 0.27 GHz and a quality factor of 148. Furthermore, Gaussian apodization enabled the out-of-band rejection of the filter to reach 34 dB and the center frequency to be finely tuned over a wide range, spanning from 4 to 14 GHz. These results indicate that the proposed scheme could provide a promising guideline for the photonic RF filters that demand both high reconfigurability and greatly reduced size and complexity.
Chinese Optics Letters
- Publication Date: Feb. 22, 2024
- Vol. 22, Issue 2, 023901 (2024)
Fifth-generation new radio signal transmission over a transparent fiber-wireless-fiber seamless system in the 75–110 GHz band
Xiang Liu, Jiao Zhang, Min Zhu, Qing Zhong, Weidong Tong, Zhigang Xin, Yunwu Wang, Bingchang Hua, Yuancheng Cai, Mingzheng Lei, Junjie Ding, Xingyu Chen, and Jianjun Yu
In this Letter, we demonstrate the transmission of fifth-generation new radio (5G NR) signals over a fiber-millimeter-wave (mmWave)-fiber mobile fronthaul system in the 75–110 GHz band for an ultra-dense small cell network. The system employs a simple all-optical conversion technology, including mmWave signal generation using an optical heterodyne and a photonics-enabled receiver based on different modulator schemes. As a proof-of-concept demonstration, we successfully transmit 400 MHz 64QAM/256QAM at 3.5 and 4.9 GHz. The proposed system can provide a simple solution for facilitating the deployment of ultra-dense small cells in high-frequency bands for 5G mmWave/intermediate-frequency-over-fiber networks. In this Letter, we demonstrate the transmission of fifth-generation new radio (5G NR) signals over a fiber-millimeter-wave (mmWave)-fiber mobile fronthaul system in the 75–110 GHz band for an ultra-dense small cell network. The system employs a simple all-optical conversion technology, including mmWave signal generation using an optical heterodyne and a photonics-enabled receiver based on different modulator schemes. As a proof-of-concept demonstration, we successfully transmit 400 MHz 64QAM/256QAM at 3.5 and 4.9 GHz. The proposed system can provide a simple solution for facilitating the deployment of ultra-dense small cells in high-frequency bands for 5G mmWave/intermediate-frequency-over-fiber networks.
Chinese Optics Letters
- Publication Date: Dec. 24, 2024
- Vol. 22, Issue 12, 123901 (2024)
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