Injectorless quantum cascade laser with two-phonon-resonance design using four alloys for emission wavelengths between 5 and 9 µm

Abstract

The wavelength-dependent threshold and power performance of an injectorless quantum cascade laser design using four alloys and the two-phonon-resonance depletion scheme were investigated. A 7 µm design, which reached threshold current densities as low as 0.45 kA cm−2 at 300 K and overall efficiencies above 2%, was taken as a reference. Variations in layer thickness and composition were applied to study the effects of coupling energy and transition time, increasing the output efficiency up to 5.7%. With regard to the transmission windows from 3 to 5 µm and 8 to 12 µm, the design scheme of the reference was also modified to emission wavelengths between 5 and 9 µm. All devices yield threshold current densities below 1.5 kA cm−2 at 300 K, and at least 550 mW of output power. The characteristic temperatures vary indirectly proportional to the emission wavelength from 100 K at 5 µm to 300 K at 9 µm.