Ratiometric wavelength monitor based on singlemode‐multimode‐singlemode fiber structure

An all‐fiber ratiometric wavelength monitor for optical wavelength measurement is proposed and investigated theoretically as well as experimentally. Two edge filters with opposite slope spectral responses based on the singlemode‐multimode‐singlemode (SMS) fiber structures are developed. A ratiometric wavelength measurement system employing the developed SMS edge filters demonstrates a high discrimination range of 20.41 dB and a potential wavelength measurement resolution of 10 pm over a wavelength range from 1530 to 1560 nm.