Mid-IR optical amplification and detection using quantum cascade lasers

Amplification and detection characteristics of mid-infrared quantum cascade lasers (QCLs) are studied. The QCL amplifier has an adjustable bandwidth and tunable gain peak to function as a tunable mid-IR filter. By biasing the QCL slightly below its threshold, we demonstrated more than 11dB optical gain and over 28dB electrical gain at specified wavelengths. In the electrical gain measurement process, the resonant amplifier also functioned as a detector. Mid-IR amplification and detection can be achieved using the same material for the laser source. This indicates that intersubband based gain materials can be ideal candidates for mid-IR photonic integrations.