Ultra-short pulse transmission in a passive white light cavity based on chirped Bragg gratings

TL;DR

This paper investigates the use of linearly chirped Bragg gratings to create a white light cavity capable of transmitting ultra-short pulses, highlighting the challenges due to multiple scattering effects that prevent simple realization.

Contribution

The study explores the dispersion-compensating properties of LCBGs for white light cavity construction and analyzes why simple configurations do not achieve the desired positive group delay.

Findings

Reflection in LCBGs occurs at multiple locations, not just where the Bragg condition is met.

Multiple scatterings inside LCBGs lead to a positive group delay.

Simple LCBG-based WLCs cannot be realized due to these scattering effects.

Abstract

It is widely accepted that Bragg reflection from linearly chirped Bragg gratings (LCBGs) can compensate for a chromatic dispersion by reflecting different wavelengths at different location along the axis of the gratings for ultra-short pulses. In this paper, we studied the possibility of making use of such a dispersion-compensating property to construct a white light cavity (WLC). A pair of LCBGs is suggested as the reflectors of the cavity. The analytical and numerical analysis shows that the reflection by a LCBG does not solely occur at the position where Bragg condition is reached. The accumulated effect of multiple scatterings at different locations inside the LCBG produces a positive group delay, preventing the WLC to be realized with simple LCBG.