Gross Simon, Coutts David W, Dubinskiy Mark, Withford Michael J
Opt Lett. 2019 Feb 15;44(4):831-834. doi: 10.1364/OL.44.000831.
Typical high power broad-area semiconductor lasers exhibit a highly astigmatic beam profile. However, many applications require a homogenous and circular symmetric beam. Thus coupling into circular multimode optical fibers is often employed. The strip-like astigmatic output of the diode laser underfills the circular multimode fiber, thus a decrease in beam quality occurs after fiber coupling due to mode mixing inside the optical fiber. This Letter presents a 3D integrated optics approach to shape the output of a broad-area laser diode. Ultrafast laser inscription is utilized to create a pair of photonic lanterns connected back to back inside a glass chip that captures and shapes the output of a commercial 976 nm wavelength broad-area laser diode with 95 μm emitter width. Compared to coupling to a 105 μm diameter, 0.15 numerical aperture step-index multimode fiber, the photonic chip-based approach results in a 13× higher beam quality and 7× greater brightness.
典型的高功率宽面半导体激光器呈现出高度像散的光束轮廓。然而，许多应用需要均匀且圆对称的光束。因此，常采用耦合到圆形多模光纤的方式。二极管激光器的带状像散输出无法完全填充圆形多模光纤，所以在光纤耦合后，由于光纤内部的模式混合，光束质量会下降。本文提出了一种三维集成光学方法来整形宽面激光二极管的输出。利用超快激光写入技术在玻璃芯片内部创建一对背对背连接的光子灯笼，该光子灯笼捕获并整形商用976纳米波长、发射极宽度为95微米的宽面激光二极管的输出。与耦合到直径为105微米、数值孔径为0.15的阶跃折射率多模光纤相比，基于光子芯片的方法可使光束质量提高13倍，亮度提高7倍。
