Efficient 970 nm Ridge Waveguide Lasers for Space-Based Power Beaming Application

In-space laser power delivery provides a route to delivering energy to where it is most needed, for example, satellites or other space vehicles temporarily eclipsed from the sun or for lunar polar/planetary exploration whereby the target (e.g. a rover) may be in permanent darkness. High power edge-emitting semiconductor lasers are a promising light source for this application owing to their very high brightness, efficiency, and small physical size. However, their temperature dependence is complex and their output beam is highly asymmetric and divergent. Here, we show high efficiency and single mode operation over a wide range of temperatures using GaAs-based ridge waveguide (RW) lasers emitting at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda=970 \mathrm{n}\mathrm{m}$</tex>. The vertical far-field divergence angle at 95% power content of the vertically collimated beam is also measured as ~6 mrad, which is good for power beaming system.