Independent Control of Mode Selection and Power Extraction in Terahertz Quantum Cascade Lasers

We demonstrate novel THz quantum cascade lasers with a gain endowed photonic crystal (PhC) and a grating coupler (GC) formed on each end of the ridge. The PhC acts as a reflection mirror with extremely narrow bandwidth, and the GC enables high radiation efficiency. Such configuration independently controls the mode control and power extraction, and results in stable single mode emission with very high output power.