Title :
DFB FL Sensor Cross-Coupling Reduction
Author :
Tikhomirov, Alexei ; Foster, Scott
Author_Institution :
Maritime Operations Div., Defence Sci. & Technol. Organ., Edinburgh
Abstract :
The effect of weak external reflections on distributed feedback (DFB) fiber laser (FL) sensor frequency noise has been studied. For multiplexed DFB FL arrays, it was demonstrated that out-of-band reflections from DFB FL raise the noise level of adjacent lasers by up to 50 dB. It was further demonstrated that by incorporating a complex phase- and amplitude-apodized FL grating design with high sidelobe suppression, cross coupling due to out-of-band reflections can be reduced to negligible levels, and Rayleigh backscatter limited noise performance can be achieved. Practical limitations to acoustic sensitivity of DFB FL sensors due to increased laser frequency noise are discussed, and ways to reduce DFB FL sensitivity to external reflections are proposed
Keywords :
acoustic transducers; acoustic variables measurement; backscatter; diffraction gratings; distributed feedback lasers; fibre lasers; laser noise; light reflection; optical sensors; remote sensing by laser beam; Rayleigh backscatter; acoustic sensitivity; acoustic sensor; amplitude apodization; complex phase apodization; cross coupling; cross-coupling reduction; distributed feedback laser sensor; fiber laser grating design; fiber laser sensor; laser frequency noise; laser noise level; multiplexed laser arrays; out-of-band reflections; sensor frequency noise; sidelobe suppression; weak external reflections; Acoustic noise; Acoustic reflection; Distributed feedback devices; Fiber lasers; Frequency; Laser feedback; Laser noise; Noise level; Noise reduction; Optical reflection; Acoustic sensor; Bragg grating; distributed feedback (DFB) lasers; laser noise; multiplexing;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2006.889096
