Wang Lijie, Li Zhen, Tong Cunzhu, Shu Shili, Tian Sicong, Zhang Jun, Zhang Xin, Wang Lijun
Appl Opt. 2018 Dec 1;57(34):F15-F21. doi: 10.1364/AO.57.000F15.
We report a near-diffraction-limited tapered Bragg reflection waveguide laser (BRL) with a 10 μm 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° shows the best far-field performance. An extremely low vertical divergence angle of 14.5° and a lateral divergence as low as 2.8° 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) 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 of less than 2. Narrow beam divergence and high beam quality of the lasers allow simple and inexpensive collimation and coupling.
我们报道了一种脊宽为10μm的近衍射极限锥形布拉格反射波导激光器（BRL），其脊宽显著大于传统设计。垂直波导中的大模式扩展使得单横向模式运行时脊宽能够按比例增加。研究了具有厚垂直波导固有特性的锥形BRL中锥角对其性能的作用。结果表明，锥角为3°的BRL表现出最佳的远场性能。实现了极低的垂直发散角14.5°和95%功率包含时低至2.8°的横向发散。展示了超过1W的连续波功率。在整个工作电流范围内，垂直光束几乎不变，具有约1.3的优异光束质量（M）。由于旁瓣贡献增加，横向光束宽度在较高电流下略有增加，但横向M小于2时仍几乎保持衍射极限。激光器的窄光束发散和高光束质量允许进行简单且廉价的准直和耦合。
