Time-Resolved Spectroscopy of Quantum Cascade Lasers operated in Pulsed Mode

Full text: Time-resolved spectroscopy with pump-probe technique is a good instrument for analyzing physical processes and material properties in quantum cascade lasers. This method was used for the characterization of lasers in continuous wave. Whereas pulsed operated laser are subject to permanent changes in their working point and thus their optical properties. In our work we present an adapted version of this measurement technique capable to study pulsed operated lasers. By synchronizing pump current and sampling we can acquire the pump pulses in narrow time slots (∼20 ns) where we assume constant working conditions. This novel measurement technique gives us the possibility to gather more accurate data including gain, phase, refractive index and calculate the temperature behaviour of quantum cascade lasers. (author)