Optical injection locking of a terahertz quantum-cascade VECESL with a diode frequency multiplier source

In this talk, we present direct optical injection locking of a 2.5 THz quantum-cascade VECSEL with a 2.5 THz electronic source, namely a diode frequency multiplier chain (FMC). The FMC outputs ~10 µW of power and locks a QC-VECSEL with ~1 mW output power over a ~300 GHz bandwidth. The high-resolution spectral properties of the QC-VECSEL are monitored with a subharmonic diode mixer, and a locked linewidth of ~1 Hz is observed with a signal-to-noise ratio of ~40 dB, in good agreement with the spectral properties of the FMC injected signal.