Stimulated emission from ZnO thin films with high optical gain and low loss

TL;DR

This paper reports on the high optical gain and low loss in ZnO thin films, demonstrating low-threshold stimulated emission suitable for optoelectronic applications.

Contribution

It provides the first measurement of the highest gain and lowest loss in ZnO films, using novel measurement techniques for stimulated emission.

Findings

Lasing thresholds of 0.32 MW/cm2 (surface) and 0.5 MW/cm2 (edge)

Gain of 1369 cm-1 for N-band emission

Losses of approximately 6.2 cm-1 and 6.3 cm-1 for N- and P-bands

Abstract

Stimulated surface- and edge-emission were investigated for ZnO thin films grown epitaxially by pulsed laser deposition. The lasing threshold was 0.32 MW/cm2 for surface pumping and 0.5 MW/cm2 for edge pumping, which is significantly lower than thresholds observed previously. A modified variable stripe length method was used to measure the gain, which was 1369 cm-1 for N-band emission. Losses were measured using the shifting excitation spot method and values of 6.2 cm-1 and 6.3 cm-1 were found for the N-band and P-band, respectively. The measured gain and loss were the highest and lowest (respectively) ever reported for ZnO films.