High-frequency modulation of a quantum-cascade laser using a monolithically integrated intracavity modulator

We report a quantum-cascade laser monolithically integrated with an intracavity modulator which could be operated up to 1 GHz. In contrast to earlier approaches, where the radio frequency (RF) modulation signal was supplied to the entire cavity length of the laser structure, we drive only a relatively small 375-μm-long section of the cavity. At the same time, a quasi-continuous-wave signal was supplied to the remaining 1125-μm-long section. This modulation scheme resulted in smaller parasitic capacitance effects than what we reported previously, and enabled us to work with lower RF voltages and currents.