Strain-compensated AlAs/(In,Ga)As heterostructures for short-wavelength intersubband absorption and laser emission

We have investigated intersubband transitions in strain-compensated AlAs/(In,Ga)As heterostructures, demonstrating both absorption and quantum-cascade laser emission at short wavelengths. Short-wavelength optical transitions in such structures are associated with a number of challenges in both the growth and design, including managing the internal strain and designing around indirect valleys. We achieve absorption peaks at wavelengths as short as 1.7μm in fully strain-compensated AlAs/(In,Ga)As structures. Quantum cascade lasers based on similar heterojunctions exhibit laser emission as short as 3.7μm. These lasers exhibit low-temperature threshold current densities of 860A/cm2 in pulsed mode and output power as high as 6 W per facet (12 W total). At room temperature, the threshold current density is 4.5kA/cm2 and the maximum power 240 mW per facet.