Simple guidelines to predict self-phase modulation patterns

TL;DR

This paper introduces a straightforward interference-based method to predict the spectral features caused by self-phase modulation in optical pulses, simplifying analysis and providing accurate peak position predictions.

Contribution

It develops a simple two- or three-wave interference model to accurately predict SPM spectral features for different pulse chirp conditions.

Findings

Two-wave model suffices for transform-limited and up-chirped pulses.

A three-wave model is needed for down-chirped pulses.

Analytical formulas accurately predict spectral peak positions.

Abstract

We present a simple approach to predict the main features of optical spectra affected by self-phase modulation (SPM), which is based on regarding the spectrum modification as an interference effect. A two-wave interference model is found sufficient to describe the SPM-broadened spectra of initially transform-limited or up-chirped pulses, whereas a third wave should be included in the model for initially down-chirped pulses. Simple analytical formulae are derived, which accurately predict the positions of the outermost peaks of the spectra.