Slow Light of an Amplitude Modulated Gaussian Pulse in Cesium Vapor

TL;DR

This paper demonstrates slow light of an amplitude modulated Gaussian pulse in cesium vapor, analyzes distortion effects, and proposes an all-optical post-processing method for pulse recovery, applicable to various slow light systems.

Contribution

It introduces a novel amplitude modulation technique to expand bandwidth utilization and a post-processing method for pulse recovery in slow light systems.

Findings

AMG pulse experiences distortion due to frequency-dependent transmission.

Spectral distribution causes simultaneous slow and fast light effects.

Proposed all-optical recovery method effectively restores the pulse.

Abstract

Slow light of an amplitude modulated Gaussian (AMG) pulse in cesium vapor is demonstrated and studied, as an appropriate amplitude modulation to a single pulse can expand its spectrum and thus increase the utilization efficiency of the bandwidth of a slow light system. In a single-$\Lambda$ type electromagnetically induced transparency (EIT) system, the slowed AMG pulse experiences severe distortion, mainly owing to the frequency dependent transmission of medium. Additionally, due to its spectral distribution, the frequency dependent dispersion of the medium causes simultaneous slow and fast light of different spectral components and thus a certain dispersive distortion of the AMG pulse. Further, a post-processing method is proposed to recover the slowed (distorted) pulse, which indicates that by introducing a linear optical system with a desired gain spectrum we can recover the pulse in an "all-optical" way. Finally, we discuss the limitations during this compensation procedure in detail. Although it is demonstrated in the cesium vapor using EIT, this method should be applicable to a wide range of slow light systems.