1：Experimental Design and Method Selection:

The study involved the fabrication and characterization of ridge quantum-cascade lasers (QCLs) emitting at a wavelength near 8 mm. The QCLs were designed for high-power output at room temperature.

2：Sample Selection and Data Sources:

Epitaxial heterostructures of QCLs were grown by molecular-beam epitaxy (MBE) on InP substrates. The active region consisted of 50 identical quantum cascades.

3：List of Experimental Equipment and Materials:

The study used a Riber 49 production system for MBE, an MDR-23 monochromator for spectral measurements, and a Vigo Systems PVI-4TE-

4：6 photodetector. Light–current characteristics were measured using a calibrated Thorlabs PM100 power meter with an S401C thermoelectric head. Experimental Procedures and Operational Workflow:

The QCLs were characterized under pumping by 75-ns current pulses with a repetition rate of 48 kHz. Spectral measurements and light–current characteristics were performed to evaluate the lasers' performance.

5：Data Analysis Methods:

The spectral data were analyzed to confirm multimode lasing near 8 mm, and the light–current characteristics were used to determine the threshold current densities and maximum output peak power.