Wide-ridge metal-metal terahertz quantum cascade lasers with high-order lateral mode suppression

Terahertz quantum cascade lasers with wide-ridge metal-metal waveguides are prone to lasing in high-order lateral modes, which reduce the maximum light output power from these devices. We have demonstrated, theoretically and experimentally, that the output power can be improved severalfold by introducing “side absorbers” into the waveguide structure, which enforce lasing in the TM00 mode with minor temperature performance deterioration. Lasers without side absorbers operate up to 168K, a current record for devices processed using indium/gold wafer bonding.