High-repetition-rate soliton-train generation using fiber Bragg gratings

We propose a high-repetition-rate soliton-train source based on adiabatic c ompression of a dual-frequency optical signal in nonuniform fiber Bragg gra tings. As the signal propagates through the grating, it is reshaped into a train of Bragg solitons whose repetition rate is predetermined by the frequ ency of initial sinusoidal modulation. We develop an approximate analytical model to predict the width of compressed soliton-like pulses and to provid e conditions for adiabatic compression. We demonstrate numerically the form ation of a 40-GHz train of 2.6-ps pulses and find that the numerical result s are in good agreement with the predictions of our analytical model. The s cheme relies on the dispersion provided by the grating, which can be up to six orders of magnitude larger than of fiber and makes it possible to reduc e the fiber length significantly. (C) 1998 Optical Society of America.