Near-infrared two-color intersubband transitions in AlN/GaN coupled double quantum wells

A study on a four-energy-level system in asymmetric AlN/GaN coupled double quantum wells has been performed by solving Schrodinger and Poisson equations self-consistently. It is found that the transition selection rule is recovered when the first two subband pairs resonate in the four-energy-level system. The anticrossing gap between the second excited state (2(odd)) and the third excited state (2(even)) can be up to 135 meV when the Al composition of the central barrier is 0.80. The absorption coefficient of intersubband transition (ISBT) between the ground state (1(odd)) and the 2(even) subband is approximately equal to that between the first excited state (1(even)) and the 2(odd) subband. The wavelengths of the 1(odd)-2(even) and the 1(even)-2(odd) ISBTs are 1.31 and 1.55 mu m, respectively. The results give possible application to the ultrafast two-color optoelectronic devices operating within optical communication wavelength range.