Abstract

We have obtained 21.4W of 2-µm intracavity OPO output and, to the best of our knowledge, this is the highest power from an intracavity OPO reported in the literature. To achieve such high average power 2-µm OPO output in a simple and compact laser system, we have adopted the diffusion-bonded walk-off compensated (DBWOC) KTP OPO pumped by the anisotropic Nd: YALO laser. Using Nd: YALO laser to pump OPO itself is new attempt that offers good potential in generating high power compact tunable laser source. The advantages of this combination lie in: i) Nd: YALO provides simple configuration for generating high power linearly polarised laser [1] for pumping OPO; ii) the walk-off compensated twin KTP crystals reducing the aperture effect[2] due to Poynting's walkoff in the critically phase-matched parametric generation and, at the same time, increasing the acceptance angle for the nonlinear interaction[3], resulting in more efficient OPO conversion; and iii) the diffusion-bonded configuration of the twin crystals eliminating optical losses at the in/out facets and the need for alignment of the two crystals. It is also worthwhile to note that our combination of Nd: YALO pump source with intracavity DBWOC KTP OPO crystals provides a very feasible solution to generate few tens of watts of OPO output in a compact laser head (< 40cm X 10cm X 10cm), with a simple layout which facilitates optical alignment and tuning.

© 2000 IEEE