Ultrafast Intersubband Relaxation Dynamics and Coherent Nonlinearity in Bulk and Waveguide structures of GaN/AlN Multiple Quantum Wells

Abstract

We have investigated the detailed ultrafast electronic relaxation dynamics and coherent nonlinearity at optical communication wavelength in GaN/AlN multiple quantum wells (MQWs), using spectral‐integrated and — resolved two‐color pump‐probe techniques in a wide energy range. First, we found that the ISBT relaxation dynamics consists of the ultrafast (∼140 fs) intersubband relaxation and slow (∼1.3 ps) carrier cooling process. Second, we have observed coherent spectrum oscillations, which show that the ISBT dephasing time is more than 100 fs at a room temperature. Finally, we have observed the polarization‐dependent absorption in waveguide structures.