Study on characteristics of acoustic modes via stimulated Brillouin scattering in photonic crystal fiber

Abstract

The effects of optical fiber parameters, pump wavelength and the fiber core refractive index in small-core photonic crystal fibers on characteristics of acoustic modes and the dependency of the acoustic modes coupling are investigated by the effective index method. The results indicate that both the mixed longitudinal acoustic mode and transverse acoustic mode jointly produce the acoustic fields, and their coupling forms the mixed acoustic mode; the propagation constant of acoustic mode can be changed by tailoring the pump wavelength or the PCF core refractive index in the process of SBS; the acoustic mode coupling increase and the phase velocity of the acoustic mode decreases with the increase of the PCF core diameter, and there is also a growing trend of the number of the acoustic modes at the same propagation constant. The velocity decreases with the increase of the frequency of the pump wave.