21 THz quantum-cascade laser operating up to 144 K based on a scattering-assisted injection design

Abstract

A 2.1 THz quantum cascade laser (QCL) based on a scattering-assisted injection and resonant-phonon depopulation design scheme is demonstrated. The QCL is based on a four-well period implemented in the GaAs/Al0.15Ga0.85As material system. The QCL operates up to a heat-sink temperature of 144 K in pulsed-mode, which is considerably higher than that achieved for previously reported THz QCLs operating around the frequency of 2 THz. At 46 K, the threshold current-density was measured as ∼ 745 A/cm2 with a peak-power output of ∼10 mW. Electrically stable operation in a positive differential-resistance regime is achieved by a careful choice of design parameters. The results validate the robustness of scattering-assisted injection schemes for development of low-frequency (ν < 2.5 THz) QCLs.

Robust Density Matrix Simulation of Terahertz Quantum Cascade Lasers

“…Indeed, in experiment, this device was found to lase between 2.6 and 3.22 THz, depending on both temperature and bias, and L-I curves deviating substantially from linear were measured. The extremely broad gain and complex bias dependence in Simulation results for three different THz QCL active region designs which demonstrated high-power [25], high-temperature [5], and low-frequency [28] operation. The operating conditions represented in the bandstructure and subband distributions are marked by the dots are for the three designs, at biases per module of 52 mV, 52 mV, and 76 mV.…”

“…We now turn to a demonstration of the model's capability to simulate widely varying designs, using fully self-consistent solutions of bandstructure, transport, and optical field strength, providing good predictions of the actual performance. This is shown by a side-by-side comparison of three different designs in Figure 2: (A) a hybrid bound-to-continuum/resonant-phonon design that has been demonstrated to have very high power [4], similar to [25], (B) a resonant-phonon design for high temperature which holds the current T max record [5], and (C) a scattering-assisted design for low frequency operation [28].…”

“…However, it comes at a cost of increased voltage drop per module, as well as the potential for reduced selectivity of injection (since LOphonon scattering is less energy selective than tunneling). In the example of our model system from [28], tunneling occurs amongst states (5,6), after which the LO-phonon scattering injection occurs to (4). The intended radiative transition is then to state (3), which is close to tunnel-coupled with states (1,2).…”

Температурная Зависимость Порогового Тока И Выходной Мощности Квантово-Каскадного Лазера С Частотой Генерации 3.3 ТГц

“…[9,10]. Другой подход основан на разработке новых схем работы ТГц ККЛ на основе GaAs/AlGaAs, где апробируются новые способы инжекции электронов [11], дизайны с подавлением паразитных каналов проводимости [12] и использование −X междолинного транспорта в GaAs [13].…”

Design for Stable Lasing of an Indirect Injection THz Quantum Cascade Laser Operating at Less Than 2 THz

“…Even this design scheme still suffers difficulties in the THz region compared with mid-IR QCLs. After several theoretical proposals [10,11,12], and a few recent experimental reports [8,13,14,15,16], II designs show promising results and demonstrate that there is high potential for attaining lowfrequency, high-temperature THz QCLs. modulation doping of the widest well (14.38 nm) were employed.…”