High-power high-brightness semiconductor lasers based on novel waveguide concepts

We have designed, fabricated and measured the performance of two types of edge emitting lasers with unconventional waveguides and lateral arrays thereof. Both designs provide high power and low divergence in the fast and the slow axis, and hence an increased brightness. The devices are extremely promising for new laser systems required for many scientific and commercial applications. In the first approach we use a broad photonic crystal waveguide with an embedded higher order mode filter, allowing us to expand the ground mode across the entire waveguide. A very narrow vertical far field of ~ 7° is resulting. 980 nm single mode lasers show in continuous wave operation more than 2 W, η wp ~ 60%, M 2 ~ 1.5, beam parameter product of 0.47 mm×mrad and a brightness ~ 1×10 8 Wsr -1 cm -2 respectively. First results on coherent coupling of several lasers are presented. In the second approach we use leaky designs with feedback. The mode leaks from a conventional waveguide into a transparent substrate and reflects back, such that only one mode at a selected wavelength is enhanced and builds up, others are suppressed by interference. 1060 nm range devices demonstrate an extremely narrow vertical far field divergence of less than 1°.