Polarization insensitive microbend fiber gratings and devices using the same

摘要

A microbend-induced fiber grating is formed from a section of optical fiber configured to exhibit "splitting" between the resonant wavelengths supported by the TE and TM components of the LP_1m mode and the resonant wavelength supported by the odd/even HE_2m components of the LP_1m mode. Since only the TE and TM components are polarization dependent, by splitting and shifting the resonant wavelengths for these modes away from a system-desired wavelength(s) supported by the odd/even HE modes, a polarization insensitive microbend-induced fiber grating can be formed. A fiber core configuration including a central core region, trench and ring is formed to exhibit a large radial gradient in core refractive index profile, with a significantly steep transition between the ring index and the trench index, to provide the desired splitting between the (undesired, polarization sensitive) TE/TM modes and the HE mode.