Terahertz quantum-cascade laser at λ≈100 μm using metal waveguide for mode confinement

We report lasing at similar to3.0 THz (lambdaapproximate to98-102 mum) in a quantum-cascade structure in which mode confinement is provided by a double-sided metal waveguide. The depopulation mechanism is based on resonant phonon scattering, as in our previous work. Lasing takes place in pulsed mode up to a heat-sink temperature of 77 K. The waveguide consists of metallic films placed above and below the 10-mum-thick multiple-quantum-well gain region, which gives low losses and a modal confinement factor of nearly unity. Fabrication takes place via low-temperature metallic wafer bonding and subsequent substrate removal using selective etching. This type of waveguide is expected to be increasingly advantageous at even longer wavelengths. (C) 2003 American Institute of Physics.