Determination of the Mueller matrix of UV-inscribed long-period fiber grating

Abstract

An explicit method for determination of the Mueller matrix elements of a commercial long-period fiber grating inscribed with ultraviolet CW laser irradiation (UV-LPFG) is presented. From the Mueller matrix obtained for such UV-LPFG, the full polarimetric response of the grating was found. Our polarimetric analysis was focused mainly on the polarization-dependent loss and other polarimetric properties, such as the polarizance, the depolarization index, and the diattenuation parameters. The full polarimetric analysis allows us to obtain more complete information than the usually reported ones, in which only two orthogonal linear polarizations are considered; for example, with our analysis, we prove that a small depolarization effect is inherent in UV-LPFG and that attenuation depends on the polarization state. This additional polarimetric information could be useful to control the output LPFG signal, for instance, for the realization of wavelength switchable or Q-switched fiber lasers, among other applications.