Room-temperature terahertz generation using vertical-external-cavity surface-emitting lasers

Abstract

Continuous wave (CW) terahertz (THz) sources are highly desirable for a plethora of applications ranging from spectroscopy [1] over quality inspection [2,3] of industrial goods to THz astronomy [4]. It is, however, still challenging to generate decent power levels from tunable room-temperature sources; in particular in the frequency window between 1 and 5 THz. Here, we present a compact, tunable room-temperature operating CW THz source capable of generating milliwatt power levels. The source is based on intracavity difference frequency generation (DFG) within a dual color vertical-external-cavity surface-emitting laser (VECSEL). For an efficient exploitation of the frequency-mixing scheme, a stable two-color operation of the laser is crucial. We additionally perform a systematic study of the temporal stability of the VECSEL emission via single-shot streak camera measurements. The experimental data is evaluated using quantitative statistical analysis schemes. Stable and unstable operation regimes are identified and the dependence on the intra-cavity power is investigated.