Optical injection locking of a THz quantum-cascade VECSEL with an electronic source

Optical injection locking of a metasurface quantum-cascade (QC) vertical-external-cavity surface-emitting laser (VECSEL) is demonstrated at 2.5 THz using a Schottky diode frequency multiplier chain as the injection source. The spectral properties of the source are transferred to the laser output with a locked linewidth of-1 Hz, as measured by a separate subharmonic diode mixer, and a locking bandwidth of-300 MHz is achieved. The large locking range is enabled by the microwatt power levels available from modern diode multipliers. The interplay between the injected signal and feedback from external reflections is studied and demonstrated to increase or decrease the locking bandwidth relative to the classic locking range depending on the phase of the feedback.& COPY; 2023 Optica Publishing Group

Automated summary

Optical injection locking is achieved for a metasurface quantum-cascade vertical-external-cavity surface-emitting laser at 2.5 THz, using a Schottky diode frequency multiplier chain as the injection source. The spectral properties of the source are effectively transferred to the laser output, with a locked linewidth of -1 Hz and a locking bandwidth of -300 MHz. The study also examines the interaction between the injected signal and external feedback, showing that the locking bandwidth can be increased or decreased relative to the classic locking range depending on the phase of the feedback.