Fig. 1. Schematic diagram of laser pulse transmission in WFBG array

Fig. 2. Δφ₁ signals received by 1th fiber with sounds waves in different directions under L=λ_sound/2

Fig. 3. Δφ₁ signals received by 1th fiber with sounds waves with high frequencies under θ₀=π/3，L=50m

Fig. 4. Δφ₁ signals received by 1th fiber with sounds waves with low frequencies under θ₀=π/3，L=50m

Fig. 5. Schematic diagram of WFBG hydrophone towed linear array

Fig. 6. Picture of secondary coating worksite of WFBG array

Fig. 7. 309-WFBG array coated with liquid crystal resin with 0.9 mm diameter

Fig. 8. Time domain reflected light intensity of WFBG arrays

Fig. 9. Reflected spectra of uncoated and coated WFBGs

Fig. 10. Picture of the worksite with optical cable for loose tube central bundle type with secondary coating of high density polyethylene

Fig. 11. Optical cable for loose tube central bundle type with secondary coating of high density polyethylene

Fig. 12. Phase-sound pressure sensitivity of hydrophone unit of towed line array testing system

Fig. 13. 5 Hz signal detected by hydrophone unit of towed line array

Fig. 14. 7.5 Hz signal detected by hydrophone unit of towed line array

Fig. 15. 10 Hz signal detected by hydrophone unit of towed line array

Fig. 16. Wavenumuber-frequency spectrum of Carpentermodel

Fig. 17. Sound pressure transfer function curve of the sheath based on Lindemann model

Fig. 18. Self noise power spectrum with the hydrophone of towed line array