High efficiency frequency tripling schemes for high-power Nd: Glass lasers

TLDR

The theory of frequency tripling in KDP crystals is reviewed. The authors compare three high‑efficiency frequency‑tripling schemes—angle‑detuned, polarization‑mismatch, and polarization‑bypass—analyzing their sensitivity to input intensity, polarization, and mismatch angles. The polarization‑mismatch scheme is preferred for current high‑power Nd:glass lasers, whereas the polarization‑bypass scheme may be optimal for future systems, and all schemes can triplet shaped pulses with minimal efficiency loss.

Abstract

A comparison is made of three schemes ("angle-detuned," "polarization-mismatch," and "polarization-bypass") permitting high efficiency frequency tripling of 1 μm laser radiation. The overall characteristics of each are examined in terms of sensitivity to input intensity, polarization angles, and mismatch angles. The "polarization-mismatch" scheme is favored for tripling current high-power 1 μm Nd:glass laser radiation with KDP crystals, while for future systems the "polarization-bypass" scheme may be optimum. All schemes permit the tripling of some shaped pulses without substantial degradation in efficiency. The theory of tripling in KDP is reviewed.