High-power GaSb-based microstripe broad-area lasers

Significance 

Presently, the demand for high-power, high-efficiency diodes lasers emitting at 2 µm atmospheric transmission windows is high for applications such as light detection and ranging, gas and liquid sensing, direct optical communications and medical treatments. Recently, researchers have demonstrated GaSb-based Type-I quantum well diode lasers under continuous wave operation at room temperature in a specific spectral range where optimal epitaxy structures have been used to improve the efficiency, threshold current and vertical far-field performance of diode lasers. The use of such broad-area waveguide has proven to be one of the most effective ways of realizing a high output power. Unfortunately, the carrier diffusion in the broad-area waveguide results in carrier leakage and accumulation at the ridge edges, thereby deteriorating the far-field performance. This issue is known far and wide and several approaches have already been put forward, however, they also possess some limitations. Therefore, in the common good, there is need for a detailed study that will help elucidate and clear the air regarding this issue once and for all.

Recently, a team of researchers led by professor Cunzhu Tong from the State Key Laboratory of Luminescence and Application, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China, proposed a study whose main objective was to develop a simple and effective approach based on the micro-stripe broad-area structure. Tong and colleagues hoped to demonstrate a high-efficiency and high-power mid-infrared GaSb-based quantum well lasers based on their proposed approach. Their work is currently published in the research journal, Applied Physics Express.

The research method undertaken involved commenced with the demonstration of the effectiveness of a broad-area waveguide with an etched micro-stripe structure in improving the carrier leakage, accumulation, and thermal behavior of GaSb-based broad-area lasers. Next, they investigated the considerably improved threshold characteristics, output power, quantum efficiency, and single-lobed far-field of the GaSb-based broad-area lasers. Eventually, the temperature-dependent light–current–voltage curves and near-field and far-field performance characteristics were measured and analyzed so as to clarify and elucidate on the mechanism behind those improvements.

The authors observed that the micro-stripe broad-area structure could effectively suppress the lateral current leakage as well as improve the temperature behavior of GaSb lasers. A comparison between the proposed micro-stripe broad-area structure and the conventional broad-area structure showed that the former possessed a higher energy conversion efficiency, in fact, more than threefold, and the threshold current density decreased by half. In addition, high characteristic temperature and high beam quality were also realized.

In their paper, High-power GaSb-based micro-stripe broad-area lasers, professor Cunzhu Tong and colleagues demonstrated the fabrication of a high-power, high-efficiency GaSb-based diode lasers with the micro-stripe broad-area structure. It was shown that the micro-stripe broad-area structure possess the potential to considerably improve the current injection efficiency and hence reduce the carrier leakage and accumulation at the ridge edges. The characteristic temperatures of threshold and quantum efficiency were elevated. A more stable and higher beam quality was realized from the named study. Altogether, these results will contribute to the development of high-power and high-beam-quality GaSb-based diode devices.

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High-power GaSb-based microstripe broad-area lasers. Advances in Engineering
Fig. 1. The schematic diagram of GaSb based QW MSBA lasers, the inset shows the structure detail.

 

High-power GaSb-based microstripe broad-area lasers. Advances in Engineering
Fig. 2. (a) Temperature dependence of light-current characteristics. The Jth (b) and the ηd (c) of MSBA devices and BA devices as a function of temperature.

 

 

About the author

Zefeng Lu received his B.S. degree in electronic science and technology from University of Electronic Science and Technology of China, Chengdu, China, in 2012. He received his Ph.D. degree in condensed matter physics from Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China, in 2018, where he is currently working as a Research Associate. His current research interests include high brightness diode lasers and mid-infrared lasers.

About the author

Cunzhu Tong, received his B.S. and M.S. degrees in physics from Chongqing University, China, and the Ph.D. degree from the Institute of Semiconductors, Chinese Academy of Sciences (CAS). He was a research fellow with Nanyang Technological University (NTU), Singapore, from 2005 to 2009. After that he joined the University of Toronto, Canada, as a post-doctoral researcher.

He became the professor of Hundred Talents Program in CAS in 2010 and was with the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), CAS, Changchun, China. He was the distinguished elite professor of CAS and senior member of IEEE. He is the deputy director of State Key Lab of Luminescence and Applications, and also a reviewer of the National Key Research and Development Plan of China.

He won several awards including the Outstanding Young Scientist Award selected by SCIENTIFIC CHINESE, the Excellent Award for Hundred Talents Program of CAS and the Important Achievements in China Optics 2015 etc. He has authored and co-authored over 90 refereed journal papers and awarded 9 patents. His current research interests include the high brightness diode lasers, beam combining, and semiconductor disk lasers.

Reference

Zefeng Lu, Lijie Wang, Yu Zhang, Shili Shu, Sicong Tian, Cunzhu Tong, Guanyu Hou, Xiaoli Chai, Yingqiang Xu, Haiqiao Ni, Zhichuan Niu, Lijun Wang. High-power GaSb-based microstripe broad-area lasers. Applied Physics Express, volume 11, 032702 (2018)

Go To Applied Physics Express

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