Analysis of effect of divergence of laser beam on prism-based inscription of fiber Bragg gratings over a wide wavelength range

Abstract

In this report, we present analysis of an inscription method for fiber Bragg gratings (FBGs) that uses diverging laser beam and a biprism. We analyze the effect of divergence on inscription characteristics of FBGs. We show that the method allows inscription of a number of FBGs, each with a different Bragg wavelength in a section of optical fiber by using a single biprism. We discuss how such tuning affects other crucial parameters of the FBGs, such as bandwidth, reflectivity, and chirp. We show that the current method allows one to control the tuning range, and tuning sensitivity, by a mere change in the divergence of the laser beam during inscription. We also show that the method can be optimized to inscribe highly chirped tilted FBGs.