Frequency domain analysis of fiber bragg grating based phase modulation to intensity modulation conversion

Abstract

In this paper, optical phase modulation to intensity modulation by the use of a fiber Bragg grating (FBG) based frequency discriminator is proposed and experimentally demonstrated. In the proposed approach, the optical carrier frequency is placed at the quadrature point of the positive or negative slope of the reflection response of the FBG. The phase modulated light reflected from the two opposite slopes will have a π phase difference, which makes bipolar operation possible in an all-optical microwave signal processor or an optical code division multiple-access system. Both the frequency and phase responses of the FBG are taken into account to build a theoretical model in a frequency domain. Phase modulation to intensity modulation conversion based on a Gaussian apodized FBG is experimentally implemented. The results confirm the theoretical analysis.