Near-diffraction-limited Bragg reflection waveguide lasers

摘要

We report a near-diffraction-limited tapered Bragg reflection waveguide laser (BRL) with a 10 mu m ridge width, which is significantly larger than the conventional design. The large mode expansion in the vertical waveguide enables a scalable increase in the ridge width for single lateral mode operation. The role of the taper angle in the performance of tapered BRLs with the intrinsic characteristics of a thick vertical waveguide was investigated. The results indicate that the BRL with a taper angle of 3 degrees shows the best far-field performance. An extremely low vertical divergence angle of 14.5 degrees and a lateral divergence as low as 2.8 degrees for 95% power inclusion were realized. A continuous-wave power exceeding 1 W was demonstrated. Over the entire operating current range, the vertical beam is almost unchanged with an excellent beam quality (M-2) of about 1.3. Lateral beam width increases slightly at higher currents due to the increasing contribution of side lobes, but it still remains nearly diffraction-limited with a lateral M-2 of less than 2. Narrow beam divergence and high beam quality of the lasers allow simple and inexpensive collimation and coupling. (C) 2018 Optical Society of America