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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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