Fig. 1. Physical image of the Virginia-Class Nuclear submarine^[7,67]

Fig. 2. Physical image of the FOH array^[27]

Fig. 3. Structure of a very low frequency interference FOH probe

Fig. 4. Frequency response of a very low frequency interferometric FOH

Fig. 5. Phase noise of a very low frequency interferometric FOH system

Fig. 6. Principle of the remote FOH array system^[81]

Fig. 7. Phase noise changes with modulation frequency^[93]

Fig. 8. Phase noises under different phase modulation indices^[93]

Fig. 9. Output spectrum when the input power is 400 mW^[98]

Fig. 10. Phase noises corresponding to different output lights^[98]

Fig. 11. Physical picture of the towed line array FOH^[102]

Fig. 12. Flow noise of the towed line array FOH^[102]

Fig. 13. Ultra short cavity BEFL based on pump pre-amplification^[115]

Fig. 14. Principle of the compact BEFL ^[116]

Fig. 15. Phase noise spectrum of the BEFL^[121]

Fig. 16. Target orientation results of the single primitive FOVH

Fig. 17. Target orientation result of 4-primitive FOVH horizontal array. (a) Orientation result of the sound pressure sub-array; (b) orientation result of the vector array

Fig. 18. Target orientation result of the FOVH vertical array. (a) Single primitive; (b) vector vertical array^[150]

Fig. 19. Structure of the FOVH

Fig. 20. Acceleration sensitivity of the FOVH

Fig. 21. Three-axis directivity of the FOVH. (a) x-axis; (b) y-axis; (c) z-axis

Fig. 22. Distributed FOH based on discrete sensitivity-enhanced structure

Fig. 23. Distributed FOH based on consecutive sensitivity-enhanced structure

Fig. 24. Structure of fading noise suppression based on frequency division multiplexing^[185]

Fig. 25. Fading noise suppression effect based on frequency division multiplexing. (a) Interference signal strength position-time domain diagram; (b) phase position-spectrogram; (c) suppressed phase position-spectrogram^[185]

Fig. 26. DAS system based on diversity reception and optimal weight averaging algorithm. (a) Structure diagram of the system; (b) experimental results