Gain spectroscopy of a type-II VECSEL chip

TL;DR

This study investigates the gain dynamics of a type-II VECSEL chip using optical spectroscopy, confirming theoretical predictions and revealing slower gain buildup due to reduced electron-hole scattering.

Contribution

It provides the first experimental validation of microscopic gain predictions for a type-II VECSEL structure at room temperature.

Findings

Gain at 1170 nm confirmed experimentally.

Slower gain buildup compared to type-I chips.

Reduced electron-hole scattering causes delayed gain dynamics.

Abstract

Using optical pump-white light probe spectroscopy the gain dynamics is investigated for a VECSEL chip which is based on a type-II heterostructure. The active region the chip consists of a GaAs/(GaIn)As/Ga(AsSb)/(GaIn)As/GaAs multiple quantum well. For this structure, a fully microscopic theory predicts a modal room temperature gain at a wavelength of 1170 nm, which is confirmed by experimental spectra. The results show a gain buildup on the type-II chip which is delayed relative to that of a type-I chip. This slower gain dynamics is attributed to a diminished cooling rate arising from reduced electron-hole scattering.