Ultrafast intersubband relaxation and nonlinear susceptibility at 1.55 μm in GaN/AlN multiple-quantum wells

摘要

Using a degenerate pump-probe technique on the Brewster configuration at room temperature, we investigate the dynamics of the intersubband transition in GaN/AlN multiple-quantum wells. The relaxation dynamics is found to consist of ultrafast (～140 fs) and slower (～1.3 ps) components. We estimate the third-order susceptibility for the Brewster configuration to be ～5.5×10~(-18) m~(2)/V~(2), which indicates that its value becomes ～2.2×10~(-16) m~(2)/V~(2) when a light beam is parallel to the well.