Feasibility study on ultrafast nonlinear optical properties of 1.55-mu m intersubband transition in AlGaN/GaN quantum wells

The feasibility of the intersubband transition (ISBT) in Al(Ga)N/GaN quantum wells (QWs) as a device mechanism for ultrafast optical switches is theoretically investigated. The 1.55-mu m ISBT is shown to Lie feasible because of its large conduction band discontinuity. The intersubband relaxation time at 1.55-mu m is estimated to be 80 fs, which is about 30 times shorter than that in InGaAs QWs, The third order nonlinear susceptibility is estimated to be 1.6 x 10(-15) ma V-2 for N = 1 x 10(18) cm(-3). These characteristics suggest that the ISBT in nitride QWs is a promising mechanism for multi-terabit/s optical switches.