Coherent Optical Fiber Sensing Based on a Frequency Shifting Loop

Billault, Vincent; Arpison, Guillaume; Crozatier, V.; Kemlin, Vincent; Morvan, Loïc; Dolfi, Daniel; Chatellus, Hugues Guillet de

doi:10.1109/jlt.2021.3060105

Cited by 10 publications

(1 citation statement)

References 26 publications

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“…Notably, the demonstrated system successfully reconstructed ISAR images of the objects without distinguishable differences from those based on the AWG. It should be noted that a minor frequency step (∆f ) can be achieved by cascading two AOMs with the opposite frequency shift (e.g., a frequency shift from -10 to +10 MHz has been demonstrated in [20]) to achieve an unambiguous range over 100 meters, which is comparable to the 120 meters unambiguous range window (1.25 MHz frequency shift) from the CARABAS system -a very early airborne synthetic aperture radar that employed SF signals -mounted on an aircraft [21].…”

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confidence: 99%

Photonic Generation of Radar Signals with 30 GHz Bandwidth and Ultra-High Time-Frequency Linearity

Zhang¹,

Yang²,

Eggleton³

2021

Preprint

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Photonic generation of radio-frequency signals has shown significant advantages over the electronic counterparts, allowing the high precision generation of radio-frequency carriers up to the terahertz-wave region with flexible bandwidth for radar applications. Great progress has been made in photonics-based radio-frequency waveform generation. However, the approaches that rely on sophisticated benchtop digital microwave components, such as synthesizers and digital-to-analog converters have limited achievable bandwidth and thus resolution for radar detections. Methods based on voltage-controlled analog oscillators exhibit high time-frequency non-linearity, causing degraded sensing precision. Here, we demonstrate, for the first time, a photonic stepped-frequency (SF) waveform generation scheme enabled by MHz electronics with a tunable bandwidth exceeding 30 GHz and intrinsic time-frequency linearity. The ultra-wideband radio-frequency signal generation is enabled by using a polarization-stabilized optical cavity to suppress intra-cavity polarization-dependent instability; meanwhile, the signal's high-linearity is achieved via consecutive MHz acousto-optic frequency-shifting modulation without the necessity of using electro-optic modulators that have bias-drifting issues. We systematically evaluate the system's signal quality and imaging performance in comparison with conventional photonic radar schemes that use high-speed digital electronics, confirming its feasibility and excellent performance for high-resolution radar applications.

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confidence: 99%

Photonic Generation of Radar Signals with 30 GHz Bandwidth and Ultra-High Time-Frequency Linearity

Zhang¹,

Yang²,

Eggleton³

2021

Preprint

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Photonic Generation of 30 GHz Bandwidth Stepped-Frequency Signals for Radar Applications

Zhang

Liu

Eggleton

2022

J. Lightwave Technol.

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Wideband microwave signals with high timefrequency linearity for high-resolution radar applications can be optically generated using high-speed electronic waveform generators. Frequency-shifting modulation in an optical cavity provides an attractive approach to generate broadband microwave signals with reduced complexity requiring only MHz-level electronics. However, the in-loop signal instability and inter-pulse interference usually cause amplitude fluctuations, leading to limited signal-to-noise ratio and signal bandwidth. Here, we overcome these challenges and demonstrate, for the first time, the photonic generation of 30-GHz-wide stepped-frequency (SF) signals with 100 MHz frequency steps defined by an MHz-level electrical oscillator. We achieved this performance by mitigating the in-loop polarization scrambling and inter-pulse interference using a polarization-maintaining cavity and a high-extinction optical switch. This allows stable consecutive acousto-optic frequency-shifting modulation that significantly improves the signal-to-noise ratio. While achieving a bandwidth surpassing the state-of-the-art demonstrations based on wideband electronics, our approach alleviates the necessity for high-speed signal generators or wideband tunable lasers. To exemplify the utility, we systematically evaluate the signal quality and show its applications in radar imaging compared to those using electrical waveform generators.

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A Frequency-Scanned Φ-OTDR Implemented by a Frequency Shifting Loop Used for Distributed Strain Sensing

Hu,

Zhang,

Yang

et al. 2024

J. Lightwave Technol.

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Coherent Optical Fiber Sensing Based on a Frequency Shifting Loop

Cited by 10 publications

References 26 publications

Photonic Generation of Radar Signals with 30 GHz Bandwidth and Ultra-High Time-Frequency Linearity

Photonic Generation of Radar Signals with 30 GHz Bandwidth and Ultra-High Time-Frequency Linearity

Photonic Generation of 30 GHz Bandwidth Stepped-Frequency Signals for Radar Applications

A Frequency-Scanned Φ-OTDR Implemented by a Frequency Shifting Loop Used for Distributed Strain Sensing

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