Electro-optically modulated lasers: pulse energy and contrast enhancement derived from theoretical spectrum

TL;DR

This paper presents an analytical method to optimize pulsed laser spectra generated by phase and intensity modulation, significantly improving pulse peak power and contrast, with applications in high-rate optical communication.

Contribution

It introduces a theoretical spectrum analysis that enhances pulse energy and contrast in electro-optically modulated lasers, enabling better spectrum correction and high-rate signal multiplication.

Findings

Up to 75% increase in peak power for given average power

Contrast ratio improved by at least three orders of magnitude

Facilitates large-factor rate multiplication with minimal signal degradation

Abstract

In this article, we derive analytically the complex optical spectrum of a pulsed laser source obtained when a frequency comb generated by phase modulation is input into a synchronized intensity modulator. We then show how this knowledge of the spectrum may help to achieve unprecedented accuracy during the experimental spectrum correction step usually carried out with an optical spectrum processor. In numerical examples, for a given average power we present up to a 75 % increase in peak power and an enhancement of the extinction ratio by at least three orders of magnitude. This method also enables large-factor rate-multiplications of these versatile coherent sources using the Talbot effect with negligible degradation of the signal.