Abstract

The concept of using tapered waveguides to couple from planar to channel waveguides is well established and various designs for adiabatic expansion of the lowest- order spatial mode from a channel to a planar waveguide region have been described. Tapered waveguides have also been employed in diode-laser systems in an attempt to produce high-power, low-divergence, diffraction-limited outputs [1], although these are often used as power amplifiers to avoid facet damage caused by having high average powers in the small channel section. Indeed, these amplifiers are often simply a flared gain region rather than an actual tapered waveguide. Here we describe the laser operation of tapered waveguides based on ion-exchanged Nd:BK7 glass. A tapered waveguide is of interest as it could allow end-pumping with broad-stripe diodes and, for materials with a strong pump absorption, side-pumping with high power diode bars. If the taper is combined with a single- mode channel and adiabatic expansion of the lowest-order spatial mode can be achieved, then there is good potential for simple and compact, high-power sources with good output beam quality.

© 2000 IEEE