The Study Of Brillouin Scattering In Optical Fiber With Micro Structure

Brillouin scattering in optical fiber is an important nonlinear effect. It is caused by the interaction between photon and acoustic phonon. Such a nonlinear effect has been widely used in structural health monitor, narrow bandwidth Brillouin laser, Brillouin optical amplifier, Brillouin filter, and slow light and so on. Because photonic crystal fiber has a multiplex structure, many new scattering characteristics are produced, study of which is valuable for the deep understanding of Brillouin scattering effect and developing new functional devices.In this article, we investigate the Brillouin characteristics in the fiber with micro‐structures, i.e., a holey fiber and an all‐solid photonic bandgap fiber, since they have relatively complicated light/acoustic guided modes which may produce many interesting scattering phenomena. Some new results are achieved. When a microstructured fiber is fusion spliced to the single‐mode fiber with a mismatch distance between the cores, the waveguide modes can be excited in the both the core and the cladding regions so that the study is enabled.The Brillouin scattering from a fiber microstructure such as multiple air holes or high‐index pillars shows a multi‐peak feature. Both the Brillouin frequency and intensity can be influenced by the environmental parameters, including the strain and temperature. For example, in the holey fiber, when the environments are changed, the main peak corresponds to a larger variation in frequency and intensity than those sub‐peaks, enabling the possibility for the device to be used as the sensors for simultaneous strain and temperature measurement.