High-power, high-spectral-purity GaSb-based laterally coupled distributed feedback lasers with metal gratings emitting at 2  μ m

Abstract

We report on the fabrication of high-power, high-spectral-purity GaSb-based laterally coupled distributed feedback (LC-DFB) lasers emitting at 2 μm. Second-order Chromium-Bragg-gratings are fabricated alongside the ridge waveguide by lift off. Due to the introduction of gain coupling, the lasers exhibit a stable single mode operation [side-mode suppression ratio (SMSR) >40 dB] from 10 °C to 50 °C and the maximum SMSR is as high as 53 dB. At a heat-sink temperature of 10 °C, the lasers emit more than 40 mW continuous-wave in a single longitudinal mode. A high external quantum efficiency of 48% is obtained, resulting in a notable increase in power conversion efficiency peaking at 13%. The lasers achieve a comparable output power with that of the index-coupled LC-DFB lasers, while maintaining a better single mode performance. Thus, we prove the feasibility of the metal-grating LC-DFB structure to achieve high-power, frequency-stable semiconductor lasers through a simpler and much more convenient way.

InAs/GaAs quantum dot laterally coupled distributed feedback lasers at 1.3 μm

“…Au/Ge/Ni/Au metal contacts were applied for the back. The design of our LC-DFB lasers was based on coupled-wave theory, and the first-order grating is used [13][14][15] . Figure 1 shows the high resolution scanning electron microscope (SEM) images, where the cleaved facet of the laser is shown in Fig.…”

Watt-level antimony laser diodes emitting at 2 μm

“…While, our group has also made several exciting progress in improving the performance of antimony lasers in the past ten years, such as power, and stability. Particularly, we expert in singlemode GaSb-based lasers, increasing the spectral purity and power of laterally coupled distributed feedback laser with a single longitudinal mode 7 . What's more, there are several breakthroughs in a single transverse mode of the high spectral purity blazed grating external cavity laser 8 and how to improve the craft process and epitaxy stability with the purpose of mass production 9 .…”

Promotion of Specific Single-Transverse-Mode Beam Characteristics for GaSb-Based Narrow Ridge Waveguide Lasers via Customized Parameter Design

“…Semiconductor diode lasers operating in the mid-infrared (mid-IR) 2–4 m wavelength region are of considerable interest owing to their excellent inherent properties of small footprint and low cost, and broad application prospects in a variety of fields, such as laser spectroscopy, free-space communication, material processing, and medical therapy [ 1 – 3 ]. Among these mid-IR diode lasers, GaSb alloys are the most promising material systems [ 3 – 5 ]. In fact, GaSb-based broad area (BA) lasers operating in the 2 m wavelength region have been reported with a maximum output power near 2 W [ 1 , 6 , 7 ].…”

“…The potential for higher output power with simultaneously good beam quality makes GaSb-based single-transverse-mode narrow ridge waveguide (RW) lasers ideally suited light sources for various scientific and commercial applications, such as pumping rare-earth-doped fiber amplifiers and solid-state lasers [ 8 – 10 ], seeding external cavity lasers [ 11 , 12 ], and nonlinear frequency conversion [ 13 ]. In addition, narrow RW structure is also widely employed in various laser devices, such as distributed-feedback (DFB) lasers [ 3 , 14 ], distributed Bragg reflector (DBR) lasers [ 15 , 16 ], superluminescent diodes (SLD) [ 5 , 17 ], semiconductor optical amplifiers (SOA) [ 18 ], and tapered lasers [ 19 ], owing to its ability to guarantee high transverse mode purity and stability, which enables the use of simple and low-cost optics for the focusing and coupling of these devices for further utilization.…”

“…In contrast, pumping or coupling applications put higher emphasis on the promotion of optical output power and the compression of beam divergence [ 10 , 18 , 19 ]. Meanwhile, GaSb-based DFB, DBR, or SLD devices require relatively deep ridge etching to obtain a more substantial coupling effect of the grating or curved structure with the active layer [ 3 , 15 , 16 ]. However, these distinctive and even competing demands were often neglected in previous research using GaSb-based single-transverse-mode laser diodes, in which a 5 -m width RW was usually adopted without systematic investigation [ 2 , 4 , 5 , 17 ].…”