A time domain beam propagation method for chirped signals

Abstract

Chirped pulses are used in time stretch analog to digital converters to stretch high speed electric signals so that they can be measured with conventional detectors. Here a time domain beam propagation method for strongly chirped signals propagating along a specified direction is presented. By examining the propagation of chirped pulses in waveguides we derive a phase factor which captures the rapidly oscillating part of the chirped pulse. We then solve for the slowly varying envelope with respect to this phase factor in a time window moving with the pulse. The new method is applied to simulation of electro-optical modulators for chirped pulses with promising results.