Gain and tuning characteristics of mid-infrared InSb quantum dot diode lasers

There have been relatively few reports of lasing from InSb quantum dots (QDs). In this work, type II InSb/InAs QD laser diodes emitting in the mid-infrared at 3.1 μm have been demonstrated and characterized. The gain was determined to be 2.9 cm−1 per QD layer, and the waveguide loss was ∼15 cm−1 at 4 K. Spontaneous emission measurements below threshold revealed a blue shift of the peak wavelength with increasing current, indicating filling of ground state heavy hole levels in the QDs. The characteristic temperature, T0 = 101 K below 50 K, but decreased to 48 K at higher temperatures. The emission wavelength of these lasers showed first a blue shift followed by a red shift with increasing temperature. A hybrid structure was used to fabricate the laser by combining a liquid phase epitaxy grown p-InAs0.61Sb0.13P0.26 lower cladding layer and an upper n+ InAs plasmon cladding layer which resulted in a maximum operating temperature (Tmax) of 120 K in pulsed mode, which is the highest reported to date.