Abstract

Injection-locking of high-power diode arrays¹ is a powerful means to improve the spectral and spatial quality of high power diode lasers. We focused, for example, the 45-mW output of a single-stripe diode laser (SDL 5422) into a 20-stripe 1 W diode laser array (Siemens 480401), coated for reduced facet reflectivity. The substantial improvement in beam quality is shown in Fig. 1. The injection-locked array emits about 80% of the 800 mW output power of the free- running array in a nearly diffraction limited beam. While, free-running, the diode is highly multi-mode, with a spectral width of 2-3 ran, the injection-locked radiation is single-mode with a width of less than 20 MHz. Injection-locking thus improved the spatial power density by a factor of 50 and the spectral power density by 5 to 6 orders of magnitude. Therefore the injection-locked array is of advantage for many applications, like nonlinear frequency conversion,² or pumping of solid state lasers with small mode volumes.

© 1994 Optical Society of America