Maximizing Performance of Quantum Cascade Laser-Pumped Molecular Lasers

Quantum-cascade-laser- (QCL) pumped molecular lasers (QPMLs) have recently been introduced as a source of powerful ($>\phantom{\rule{-2pt}{0ex}}1$ mW) tunable THz) narrow-band ($<\phantom{\rule{-2pt}{0ex}}10$ kHz) continuous-wave terahertz radiation. The performance these depends critically on collision physics, pump saturation, and the design laser cavity. Using validated three-level model that captures essential saturation behaviors QPML gas nitrous oxide (${\mathrm{N}}_{2}\mathrm{O}$), we explore how threshold power output depend pressure, well diameter, length, output-coupler transmissivity cylindrical analysis indicates maximum occurs is minimized in manner much more sensitively pressure than cell or transmissivity. A near-optimal compact cavity can produce tens milliwatts over frequencies above 1 THz when by multiwatt QCL.