We report on the fabrication of GaSb-based type-I quantum well distributed Bragg reflector (DBR) lasers operating in the 2-μm region. Second-order metallic gratings of chromium are patterned by electron beam lithography. The fabricated DBR lasers emit a single-mode continuous wave at 2.04 μm. The side mode suppression ratio (SMSR) is as high as 35dB with a narrow line-width of 37MHz. The devices show a stable single mode operation with current tuning rate of 0.006nm/mA.
We report the optimum growth parameters of InAs/AlSb superlattices (SLs) for interband cascade lasers (ICL) grown by the solid-source molecular beam epitaxy(MBE). The InAs/AlSb superlattices samples were grown on GaSb substrate at different temperatures and characterized by high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and photoluminescence (PL). By changing the group-Ⅴ flux ratio during the SLs growth, the InAs/AlSb superlattices matched to GaSb substrate were obtained. Subsequently, the SLs were grown at different growth temperature. By photoluminescence we found the highest PL intensity was obtained when the SLs samples were grown at 458°C and the PL wavelength is at 1730 nm. From 10 × 10 μm2 AFM image, we found the root mean square (RMS) of the sample grown at 458°C was 1.96 Å which indicates the low surface roughness and god surface morphology.
Special processing of rapid thermal annealing on the cavity coating films for 1950 nm wavelength antimonide quantum well Laser diodes are studied. The maximum output power of the laser is greatly improved by RTA process on cavity facet films from around 610mW to above 700mW. The power conversion efficiency is further improved by the simple process by 23.2% than that of the laser coated. And the laser devices become more reliable and have extended service life after the process.
The semiconductor epitaxial design and lasing characteristics of an optically barrier-pumped GaSb -based semiconductor disk laser (SDL) emitting at 2.0 μm optimized for resonant optical barrier pumping around 1470 nm are presented. Compared to conventional barrier-pumped devices with pump wavelength of 980nm, the novel barrier-pumped device with the smaller quantum deficit reaches a significantly higher power efficiency, and thus a higher output power at a given pump power, due to the lesser internal heat generation. Using an intracavity SiC heat spreader, a cw output power in excess of 300 mW has been achieved at a heat sink temperature of +15 °C, and still more than 500 mW at +10 °C.
We report the wavelength tuning of type-II “W” quantum well of interband cascade laser. By changing the thickness of the InAs electron well, the wavelength of the active region is adjusted. We found that the whole 3-4 μm spectra can be realized and the intensity was basically the same by measuring the photoluminescence (PL) of the active region. It showed that the type-II “W” quantum well of interband cascade laser can achieve 3-4 μm range without attenuation. In addition, we calculated the wavelength of quantum well of different InAs thickness by the 8-band k·p method. And we found that the wavelength of the active region varies with the thickness of the InAs electron well, which is consistent with the theory. In addition, the measured wavelength was different from the theoretical wavelength, which may be due to the As incorporation. The incorporation of As into the InGaSb layer will lead to blue shift in the wavelength.