Analytical Instrumentation, Methods & Materials
Terahertz Quantum Cascade Lasers
Inventors: Dan Botez, Christopher Sigler, Thomas Earles, Jeremy Kirch
A terahertz quantum cascade laser device is provided comprising a substrate having a top substrate surface, a bottom substrate surface, and an exit facet extending between the top substrate surface and the bottom substrate surface at an angle θtap. The device comprises a waveguide structure having a top surface, a bottom surface, a front facet extending between the top surface and the bottom surface and positioned proximate to the exit facet, and a back facet extending between the top surface and the bottom surface and oppositely facing the front facet. The waveguide structure comprises a quantum cascade laser structure configured to generate light comprising light of a first frequency ω1, light of a second frequency ω2, and light of a third frequency ωTHz, wherein ωTHz=ω1−ω2; an upper cladding layer; and a lower cladding layer. The device comprises a distributed feedback grating layer configured to provide optical feedback for one or both of the light of the first frequency ω1 and the light of the second frequency ω2 and to produce lasing at one or both of the first frequency ω1 and the second frequency ω2, thereby resulting in laser emission at the third frequency ωTHz at a Cherenkov angle θTHz through the bottom surface of the waveguide structure into the substrate and exiting the substrate through the exit facet. The device comprises a high-reflectivity coating on the front facet of the waveguide structure.