Terahertz electroluminescence from superlattice quantum cascade structures

Abstract

Intersubband electroluminescence is reported in a quantum-cascade structure based on asymmetric superlattice active regions and designed for emission in the THz range ͑Ϸ80 m͒. Comparison with a structure based on a ''vertical transition'' in a single quantum well shows an increased full width at half maximum ͑2.8 vs 0.9 meV͒ of the emission line. In both cases the dependence of the optical power on the injected current is linear or sublinear and remains in the pW range.

Self-consistent scattering model of carrier dynamics in GaAs-AlGaAs terahertz quantum-cascade lasers

“…This has stimulated a number of experimental [9], [10] and theoretical [11] studies of QCL structures designed for emission at terahertz frequencies well below the forbidden phonon Reststrahlenband. Considerable research effort has recently resulted in theoretical prediction of population inversion by Monte Carlo studies [12], followed by luminescence measurements [13], and finally the laser action [14] at m (4.4 THz) in a GaAs-AlGaAs QCL.…”

Terahertz-frequency quantum oscillator operating in the positive differential resistance region

“…From the point of view of photonics, though photo-mixers are able to generate terahertz power output at several terahertz frequencies, the output power is limited to the W µ level or below [11]. While type-II quantum cascade (QC) lasers generate power output in mid-infrared range [12], type-I QC-lasers can deliver only 5 ~ 19 pW at 2.5THz as reported in a recent experiment [13]. The value of this output power is too small to obtain system application.…”

“…As such, we believe that the potential and future solid state power sources that will fill the Gap have to combine the features of particle (transport based devices) and waves (wave based devices) [17][11]. The devices should be "quantum transport devices" [12]. Based on this philosophical idea, we present the following theory for the design of terahertz frequency quantum oscillators operating in the positive differential resistance region.…”

Negative intersubband absorption in biased tunnel-coupled wells

“…5 Stimulated THz emission has recently been reported in tunnel-coupled cascade structures, 6 following previous investigations of the spontaneous THz emission. 7,8 The investigation of different mechanisms to achieve population inversion in structures with closely spaced levels is now timely. In this paper we study the conditions for the stimulated emission of THz radiation from independently contacted tunnel-coupled double quantum well ͑DQW͒ structures where population inversion can be realized by using the contacts to control the electron concentrations and quasi-Fermi levels in the upper (u-͒ and lower (l-͒ QW's ͓see Fig.…”