Synchronous Characterization of Semiconductor Microcavity Laser Beam

TL;DR

This paper introduces a high-resolution imaging technique to map the intensity and frequency distribution of semiconductor microcavity laser beams, revealing inhomogeneities below threshold and homogeneity above threshold, with detailed spatial and temporal analysis.

Contribution

The study presents a novel synchronous imaging method for detailed spatial and temporal characterization of laser beams, including frequency and intensity distributions, with insights into beam homogeneity and fluctuations.

Findings

Laser frequency is inhomogeneous below threshold.

Laser frequency becomes homogeneous above threshold.

Beam deviations from Gaussian shape are linked to wavelength fluctuations.

Abstract

We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross-section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center and the defects-related spectrum can also be extracted from these high-resolution pictures.