Very high-resolution optical spectral analysis based on Brillouin dynamic gratings

Abstract

In this paper, a novel method for an ultrahigh resolution optical spectrometry based on Brillouin dynamic gratings (BDGs) is proposed and demonstrated. A coherent acoustic wave is generated in an optical fiber through stimulated Brillouin scattering, and the acoustic wave modulated the fiber refractive index forming a BDG. An ultra-narrow bandwidth optical filter is constructed by operating a BDG in a long single-mode fiber (SMF), and the optical spectrometry is performed by sweeping the center wavelength of the BDG-based filter through a swept-tuned laser. In the experiment, a 4-fm (0.5 MHz) spectral resolution is achieved by operating a BDG in a 400-m SMF.