Mid/far-infrared semiconductor devices exploiting plasmonic effects

摘要

We show how metallic waveguides offer the opportunity of implementing interesting functionalities for semiconductor lasers within a simple technological approach. In the THz, we show that the active region thickness of quantum cascade lasers can be reduced by a factor of 2 without effects on the threshold current density and maximum operating temperature of the laser. Pulsed and continuous-wave operation with a low threshold J_(th)= 71 A/cm~2 are obtained for a 5.86-μm-thick THz QC laser. The emission is peaked at λ≈115 μm and the waveguide resonator is based on a metal-metal geometry. In the mid-infrared, we demonstrate surface-plasmon distributed-feedback quantum cascade lasers with a first-order grating realised by the sole patterning the top metallic contact. The devices have a single mode emission with a side-mode suppression ratio greater than 20dB. The emission wavelength at 78K is centred at λ = 7.3 μm and has tuning rate as a function of the temperature of ≈0.4 nm/K.