Terahertz quantum cascade lasers with metal-metal waveguides

摘要

Quantum cascade lasers that operate in the underdeveloped terahertz spectral range (1–10 THz) promise tocontribute to applications in sensing, spectroscopy, and imaging. We describe our development of terahertzquantum cascade lasers based on the resonant-phonon depopulation concept and that use low-loss metal-metalwaveguides for optical confinement. Two- and three-dimensional finite-element simulations of terahertz metalmetalwaveguides are used to demonstrate their high modal confinement even for very narrow ridges. Also,simulations predict high facet reflectivities due to the modal impedance mismatch with free space at the subwavelengthwaveguide aperture of these metal-metal waveguides. Finally, we report the demonstration of a2.8 THz laser that operates up to 97 K in continuous-wave mode fabricated using a Cu-Cu thermocompressionbonding technique.