Application of PM-EDF ring laser with cascaded-chirped LPG to intensity-modulation-based acoustic sensing

We have proposed EDF laser sensors using cascaded chirped long-period optical fiber gratings (C-CLPGs) as wavelength selection elements and sensing devices, and have been investigating their high performance. In particular, we demonstrated that a σ-cavity EDF laser with a double-pass C-CLPG configuration assisted by a Faraday-rotation-mirror (FRM), enabling round-trip transmission through the C-CLPG within the cavity (EDFσL) achieves a birefringence compensation effect in the C-CLPGs, which enables stable oscillation even during sensing operations. Furthermore, we previously proposed a novel polarization-maintaining EDFσ laser (PM-EDFσL) using a polarization-maintaining EDFA (PM-EDFA) to realize a high-precision laser-type sensor with enhanced oscillation stability. In this study, we achieved highly stable oscillation output in the PM-EDFσL and explored its application to intensity-modulated acoustic sensing. Experimental results successfully demonstrate the detection of mechanical vibrations.