Compact All-Quantum-Dot-Based Tunable THz Laser Source

We demonstrate an ultracompact, room temperature, tunable terahertz (THz) generating laser source based on difference-frequency-driven photomixing in a coplanar stripline InAs/GaAs quantum-dot (QD) antenna pumped by a broadly tunable, high power, continuous wave InAs/GaAs QD laser diode in the double-grating quasi-Littrow configuration. The dual-wavelength QD laser operating in the 1150- 1301 nm wavelength region with a maximum output power of 280 mW and with tunable difference-frequency (277 GHz to 30 THz) was used to achieve tunable THz generation in the QD antenna with a photoconductive gap of 50 μm. The best THz output performance was observed at pump wavelengths around the first excited state of the InAs/GaAs QDs (~1160 nm), where a maximum output power of 0.6 nW at 0.83 THz was demonstrated.