High-Q resonant cavities for terahertz quantum cascade lasers

A. Campa, L. Consolino, M. Ravaro, D. Mazzotti, M. S. Vitiello, S. Bartalini, P. De Natale
2015 Optics Express  
We report on the realization and characterization of two different designs for resonant THz cavities, based on wire-grid polarizers as input/output couplers, and injected by a continuous-wave quantum cascade laser (QCL) emitting at 2.55 THz. A comparison between the measured resonators parameters and the expected theoretical values is reported. With achieved quality factor Q ≈ 2.5 × 10 5 , these cavities show resonant peaks as narrow as few MHz, comparable with the typical Doppler linewidth of
more » ... ppler linewidth of THz molecular transitions and slightly broader than the free-running QCL emission spectrum. The effects of the optical feedback from one cavity to the QCL are examined by using the other cavity as a frequency reference.
doi:10.1364/oe.23.003751 pmid:25836227 fatcat:75k6tkkdtfdgjfnqo32tquck6q