Effective far infrared laser operation with mesh couplers

Abstract

In the pursuit of increased far infrared (FIR) laser output power and higher beam quality, we have designed, fabricated and applied hybrid metal mesh couplers. Fourier Transform Spectroscopy was performed to evaluate the spectral characteristics of the couplers. With smallest mesh features of 1.0 μm, these couplers, fabricated in a class 100 clean-room, exhibited remarkably wide bandpass characteristics. Application in an Apollo Model 122 FIR laser system resulted in high output powers on many lines in the 100–500 μm range, with only moderate pump powers (10–60 W). A careful analysis of the FIR laser beam showed undiffracted Gaussian beam profiles with low divergence angles.