Model of a Terahertz Quantum-Cascade Laser Based on Two-Dimensional Plasmons

The characteristics of a two-dimensional plasmon amplified in an active medium based on a terahertz quantum-cascade structure are calculated. It is shown that, for realistic parameters of GaAs/AlGaAs quantum-well structures (mobility of 2 × 10 5 cm 2 V –1 s –1 for an electron concentration of 5 × 10 11 cm −2 and temperatures up to 77 K), the gain experienced by two-dimensional plasmons can be as high as 1500 cm –1 at a frequency of 2.3 THz. Furthermore, due to strong localization of the plasmon electric field near a quantum well, a quantum-cascade active region with only a few periods is sufficient for amplification.