Quantum-Cascade Lasers Pass Detection Test

Research exploring directly modulated quantum-cascade lasers as telecommunications detectors generally has used HgCdTe materials, but intersubband devices and intracavity modulators also show potential for high-speed detection.

Accordingly, physicists at the University of Neuchâtel in Switzerland evaluated two quantum-cascade laser structures operating as photodetectors up to room temperature. One was a 5.3-µm two-phonon-resonance structure that demonstrated a peak responsivity of 120 µA/W at 2200 cm^-1 and that operated at temperatures up to 325 K. The other device, a 9.3-µm bound-to-continuum transition laser, had a responsivity of only 50 µA/W at 1330 cm^-1 and operated up to 297 K.

As reported in the Oct. 7 issue of Applied Physics Letters, the absorption peak of both devices shifted easily with application of a low-voltage bias, suggesting applications in free-space optical communications.