[1] Tang B, Meng D, Huang J B. Sound pressure sensitivity frequency response of polyurethane end surface pulling fiber laser hydrophone[J]. Chinese Journal of Lasers, 46, 1010004(2019).

[2] Li R Z. Research on key technology of DFB fiber laser hydrophone[D](2014).

[3] Todd M D, Seaver M, Bucholtz F. Improved, operationally-passive interferometric demodulation method using 3×3 coupler[J]. Electronics Letters, 38, 784-786(2002).

[4] Kersey A D, Berkoff T A, Morey W W. High-resolution fibre-grating based strain sensor with interferometric wavelength-shift detection[J]. Electronics Letters, 28, 236-238(1992).

[5] Brown D A. A symmetric 3×3 coupler based demodulator for fiber optic interferometric sensors[J]. Proceedings of SPIE, 1584, 328(1991).

[6] Jing S Q, Huang L, Dong W H et al. Positive and negative feedback judgment and high-frequency vibration detection by interferometer based on 3×3 coupler[J]. Acta Optica Sinica, 39, 0712001(2019).

[7] Zhang X J, Kang C, Sun J H. Demodulation method based on the 3×3 optical fiber coupler[J]. Chinese Journal of Luminescence, 34, 665-671(2013).

[8] Mao X, Huang J B, Gu H C. Demodulation technology of distributed feedback fiber laser sensor based on 3×3 coupler[J]. Chinese Journal of Luminescence, 38, 395-401(2017).

[9] Feng L, Xiao H, Zhang S W et al. Improvement of wavelength interrogation for fiber Bragg grating laser sensor system based on 3×3 couplers[J]. Chinese Journal of Lasers, 35, 1522-1527(2008).

[10] Todd M D, Johnson G A, Chang C C. Passive, light intensity-independent interferometric method for fibre Bragg grating interrogation[J]. Electronics Letters, 35, 1970-1971(1999).

[11] Zhao Z Q, Demokan M S. MacAlpine M. Improved demodulation scheme for fiber optic interferometers using an asymmetric 3×3 coupler[J]. Journal of Lightwave Technology, 15, 2059-2068(1997).

[12] Schliep F. Nonideal behaviour of single mode fibre-optic 3×3 directional couplers[J]. Electronics Letters, 31, 1496-1498(1995).

[13] Liu T T, Cui J, Chen D S et al. A new demodulation technique for optical fiber interferometric sensors with[3×3]directional couplers[J]. Chinese Optics Letters, 6, 12-15(2008).

[14] Wang W, Tang Y, Zhang X X et al. Elliptical-fitting cavity length demodulation algorithm for compound fiber-optic Fabry-Perot pressure sensor with short cavity[J]. Acta Optica Sinica, 39, 0606001(2019).

[15] Gu H C, Huang J B, Yuan B C et al. Fiber laser acoustic pressure sensing system based on interferometric demodulation technique[J]. Opto-Electronic Engineering, 35, 73-77, 81(2008).

[16] Cao J N, Yu X Z, Zhu X F et al. Study of AGC in PGC detection in interferometric fiber optic sensors[J]. Journal of Harbin Engineering University, 28, 930-934(2007).