Abstract

Recently we have reported operation of the planar waveguide type of Nd:YAG laser at up to 149 W cw output, using multi-pass pumping through the largest face in a high reflectance chamber [1]. The waveguide structure is diffusion bonded with a 200 |tm thick, 1.1 % at. Nd doped active layer enclosed by 400μm thick non-doped YAG claddings. The pumping arrangement (shown schematically in Fig. 1) is similar to that reported earlier for quasi-CW pumping of thin Nd:glass slabs [2]. Light from an array 10 cw diode bars (pitch a= 5 mm), each operating up to 40 W, is injected directly through narrow slots (width w =0.5 mm) in one face of the rectangular high reflectance pump chamber. Pump light is absorbed efficiently by up to 20 passes through the optically thin 200μm core. The arrangement has the advantages of being readily scaled to higher powers in proportion to the pump face area and gives extremely uniform pumping as each volume of the core receives light from many different diode emitters. The 60 mm long by 11 mm wide planar waveguide structure is directly cooled by water in a transverse flow channel formed by two silica windows.

© 2001 EPS