Coherent terahertz waves based on difference-frequency generation in an annealed zinc–germanium phosphide crystal: improvements on tuning ranges and peak powers

Abstract

We have efficiently generated a monochromatic terahertz wave continuously tunable in the ranges of 83.1–1642 μm and 80.2–1416 μm as a result of phase-matched difference-frequency generation in an annealed zinc–germanium phosphide crystal. The highest output peak power achieved by us is 134 W. Compared with our previous result, we have significantly improved the tuning ranges and peak powers by using a longer and annealed crystal with much lower absorption coefficients at the two pump wavelengths. Moreover, we have discussed the possibility of using intracavity difference-frequency generation to implement a compact THz source.