High-temperature, continuous-wave operation of terahertz quantum-cascade lasers with metal-metal waveguides and third-order distributed feedback

Abstract

Currently, different competing waveguide and resonator concepts exist for terahertz quantum-cascade lasers (THz QCLs). We examine the continuous-wave (cw) performance of THz QCLs with single-plasmon (SP) and metal-metal (MM) waveguides fabricated from the same wafer. While SP QCLs are superior in terms of output power, the maximum operating temperature for MM QCLs is typically much higher. For SP QCLs, we observed cw operation up to 73 K as compared to 129 K for narrow (≤ 15 μm) MM QCLs. In the latter case, single-mode operation and a narrow beam profile were achieved by applying third-order distributed-feedback gratings and contact pads which are optically insulated from the intended resonators. We present a quantitative analytic model for the beam profile, which is based on experimentally accessible parameters.

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

“…We propose that the model could therefore be used for rapid dynamical simulation of QCL designs. Terahertz-frequency quantum cascade lasers (THz QCLs) are compact, electrically driven sources of coherent radiation in the 1-5 THz band, 1 with peak (pulsed) emission powers now in excess of 1 W and operating temperatures up to 200 K. 2,3 THz QCLs are also promising continuous-wave (cw) sources, although they have poorer thermal performance and, to date, the maximum achievable cw operating temperature has been $129 K. 4 Their carrier dynamics are sensitive to temperature, and the corresponding output power degrades rapidly as temperature increases. As such, there is a requirement to understand and mitigate the influence of the temperature dependence of carrier dynamics upon the QCL behavior.…”

Гетероструктуры Одночастотных И Двухчастотных Квантово-Каскадных Лазеров

“…На сегодняшний день достигнута максималь-ная выходная оптическая мощность квантово-каскадного лазера (ККЛ) терагерцового диапазона около 100 мВт ( f = 4.4 ТГц) и 2.4 Вт ( f = 4.4 ТГц) в непрерывном [3] и импульсном [4] режимах работы соответственно. Макси-мальная рабочая температура ККЛ терагерцового диапа-зона составляет 130 K ( f = 3.0 ТГц) в непрерывном [5] и 200 K ( f = 3.2 ТГц) в импульсном [6] режимах.…”

4.7-THz Local Oscillator for the GREAT Heterodyne Spectrometer on SOFIA

“…They can provide high output powers up to several mW [8], continuous-wave (cw) operation up to 129 K [9], small intrinsic line widths of about 90 Hz [10], and sufficient frequency tunability of several gigahertz (GHz). In a few laboratory experiments, some basic demonstrations regarding the feasibility of a QCL-based LO such as pumping of a mixer, noise temperature measurements [11], [12], frequency and phase locking [13], [14] as well as heterodyne spectroscopy [15] have been demonstrated.…”