[1] [1] DANDRIDGE A. Fiber optic interferometric sensors at sea [J]. Optics and Photonics News, 2019, 30（6）: 34-44.

[2] [2] TOKY A, SINGH R P, DAS S. Localization schemes for underwater acoustic sensor networks-a review [J]. Computer Science Review, 2020, 37: 100241-1-100241-18.

[4] [4] GUO Y, MARIN J M, ASHRY I, et al. Submarine optical fiber commu-nication provides an unrealized deep-sea observation network [J]. Scientific Reports, 2023, 13（1）: 15412-1-15412-10.

[6] [6] HE X G, WU X M, WANG L, et al. Distributed optical fiber acoustic sensor for in situ monitoring of marine natural gas hydrates production for the first time in the Shenhu Area, China [J]. China Geology, 2022, 5（2）: 322-329.

[7] [7] MARTINS H F, MARTIN-LOPEZ S, CORREDERA P, et al. Coherent noise reduction in high visibility phase-sensitive optical time domain reflec-tometer for distributed sensing of ultrasonic waves [J]. Journal of Lightwave Technology, 2013, 31（23）: 3631-3637.

[8] [8] WANG Z, ZHANG L, WANG S, et al. Coherent Φ-OTDR based on I/Q demodulation and homodyne detection [J]. Optics Express, 2016, 24（2）: 853-858.

[9] [9] SORIANO-AMAT M, MARTINS H F, DURAN V, et al. Time-expand-ed phase-sensitive optical time-domain reflectometry[J]. Light: Science & Applications, 2021, 10（3）: 443-454.

[10] [10] LU B, WU B, GU J, et al. Distributed optical fiber hydrophone based on Φ-OTDR and its field test [J]. Optics Express, 2021, 29（3）: 3147-3162.

[11] [11] ALMUDEVAR A, SEVILLANO P, VICENTE L, et al. Unsupervised anomaly detection applied to Φ-OTDR [EB/OL]. [2023-06-29]. https://doi.org/10.3390/s22176515.

[12] [12] ZINSOU R, LIU X, WANG Y, et al. Recent progress in the performan-ce enhancement of phase-sensitive OTDR vibration sensing systems [EB/OL]. [2023-06-29]. https://www.xueshufan.com/publication/2918977909.

[13] [13] QIN Z, CHEN L, BAO X. Wavelet denoising method for improving detection performance of distributed vibration sensor[J]. IEEE Photonics Technology Letters, 2012, 24（7）: 542-544.

[14] [14] SHI Y, FENG H, ZENG Z. A long distance phase-sensitive optical time domain reflectometer with simple structure and high locating accuracy [J]. Sensors （Basel, Switzerland）, 2015, 15: 21957-21970.

[15] [15] QIN Z, CHEN H, CHANG J. Detection performance improvement of distributed vibration sensor based on curvelet denoising method [EB/OL]. [2023-06-29]. https://www.xueshufan.com/publication/2626843635.

[16] [16] LI D, LOU S, XIN Q, et al. SNR enhancement of far-end disturbances on distributed sensor based on phase-sensitive optical time-domain reflecto-metry [J]. IEEE Sensors Journal, 2021, 21（2）: 1957-1964.

[17] [17] MUANENDA Y, OTON C J, FARALLI S, et al. A cost-effective distri-buted acoustic sensor using a commercial off-the-shelf DFB laser and direct detection phase-OTDR [J]. IEEE Photonics Journal, 2016, 8: 1-10.

[18] [18] WANG Z-N, ZHANG B, XIONG J, et al. Distributed acoustic sensing based on pulse-coding phase-sensitive OTDR [J]. IEEE Internet of Things Journal, 2019, 6: 6117-6124.

[19] [19] SORIANO-AMAT M, MARTINS H F, DURAN V, et al. Quadratic phase coding for SNR improvement in time-expanded phase-sensitive OT-DR [J]. Optics Letters, 2021, 46（17）: 4406-4409.

[20] [20] MARTINS H F, MARTIN-LOPEZ S, CORREDERA P, et al. Distri-buted vibration sensing over 125 km with enhanced SNR using phi-OTDR over a URFL cavity [J]. Journal of Lightwave Technology, 2015, 33: 2628-2632.

[21] [21] CHOI K N, TAYLOR H F. Spectrally stable Er-fiber laser for applic-ation in phase-sensitive optical time-domain reflectometry [J]. IEEE Photo-nics Technology Letters, 2003, 15（3）: 386-388.

[22] [22] QIAN H, LUO B, HE H, et al. Phase demodulation based on DCM algorithm in Φ-OTDR with self-interference balance detection [J]. IEEE Photonics Technology Letters, 2020, 32: 473-476.

[23] [23] CHEN Y, MAO B M, ZHOU B, et al. Improving the SNR of the phase-OTDR by controlling the carrier in the SOA [J]. Journal of Modern Optics, 2020, 67: 1241-1246.

[24] [24] MARTINS H F, MARTIN-LOPEZ S, CORREDERA P, et al. Phase-sensitive optical time domain reflectometer assisted by first-order Raman amplification for distributed vibration sensing over>100 km [J]. Journal of Lightwave Technology, 2014, 32: 1510-1518.

[25] [25] ZULKIFLI M Z, HASSAN N A, AWANG N A, et al. Multi-wavelength fiber laser in the S-band region using a Sagnac loop mirror as a comb generator in an SOA gain medium [J]. Laser Physics Letters, 2010, 7（9）: 673-676.

[26] [26] HE X, XIE S, LIU F, et al. Multi-event waveform-retrieved distributed optical fiber acoustic sensor using dual-pulse heterodyne phase-sensitive OTDR[J]. Optics Letters, 2017, 42（3）: 442-445.

[27] [27] MUANENDA Y. Recent advances in distributed acoustic sensing based on phase-sensitive optical time domain reflectometry [J]. Journal of Sensors, 2018, 22: 1-16.

[28] [28] MADRIGAL J, FRAILE-PELAEZ F J, ZHENG D, et al. Characterization of a FBG sensor interrogation system based on a mode-locked laser scheme [J]. Optics Express, 2017, 25（20）: 24650-24657.

[29] [29] GAO X, HU W, DOU Z, et al. A method on vibration positioning of Φ-OTDR system based on compressed sensing [J]. IEEE Sensors Journal, 2022, 22（16）: 16422-16429.