2.9 THz quantum cascade lasers operating up to 70K in continuous wave

Abstract

We report the operation of a quantum cascade laser emitting at a 103μm wavelength (2.9THz). The active region is based on a bound-to-continuum design allowing a low parasitic leakage current, and a high upper-to-lower-state lifetime ratio. The latter is demonstrated by a pronounced decrease of the differential resistance at threshold, which is visible up to high temperatures, and by a weak temperature dependence of the slope efficiency. At 4K, we report a threshold current density of only 105A∕cm2 both in pulsed and continuous-wave operation, and an emitted peak power of 15mW independent of the duty cycle. Maximum operating temperatures of 95K and 70K are observed in pulsed and continuous wave modes, respectively.

Phase-resolved measurements of stimulated emission in a laser

“…1c. The laser, processed into ridges of 170 μm width and 2 mm length, emits at 2.87 THz and operates at sink temperatures up to 90 K [21]. The typical dependence of the THz output power and the applied voltage on the driving current density is shown in Fig.…”

“…The measurement is performed on a AlGaAs/GaAs terahertz quantum cascade laser with a bound-to-continuum optical transition [20,21]. The THz-QCL's active region consists of 90…”

Influence of doping density on electron dynamics in GaAs∕AlGaAs quantum cascade lasers

“…16,18 Since the realization 13 of the GaAs-based quantum cascade laser, an impressive extension of the attainable infrared frequency range has been achieved and can be operated at wavelengths as long as 160 m. 20 The design of QCLs based on GaAs/ AlGaAs can be made very flexible by varying the Al content due to naturally occurring near lattice matched material system across the full range of Al contents. Hence, following the first terahertz QCL, 21 several laser designs based on 15% Al content in the barriers were presented, approaching high temperature pulsed operation 22 ͑137 K͒ and above 23 or close to 24 liquid nitrogen temperature cw operation.…”

Single mode terahertz quantum cascade amplifier

“…10. 90 repeat periods of a GaAs/Al 0.15 Ga 0.85 As heterostructure were grown by molecular beam epitaxy, and the device was fabricated into a single plasmon geometry by wet etching and cleaved into a 250 lm wide, 1.33 mm long Fabry-Perot ridge cavity.…”