三种不同端面光纤列阵和半导体激光列阵耦合的(数值)模拟

Numerical Simulations of the Coupling between Laser Diode Arrays and Three Different Fiber Arrays

半导体激光列阵的输出光束有较大的发散角和较强的不对称性,极大地限制了其在各领域中的应用。为了改善半导体激光列阵输出光束的质量,必须采用特殊的光学系统进行光束整形。一种简单有效的方法是利用光纤列阵实现光束由线性排列到圆形排列的转换。对三种特殊制备的光纤列阵和半导体激光列阵的耦合特性进行了数值模拟研究。结果显示,相对于球形端面光纤列阵和锥形端面光纤列阵,球顶锥形端面光纤列阵和半导体激光列阵有着更高的耦合效率 (90%以上 )。此外,利用球顶锥形端面光纤列阵还可以进一步压缩输出光束的发散角,从而获得更高质量的输出光束。

High-power laser diode arrays are difficult to use directly in such fields as military, industry, and medicine because of their extremely asymmetric divergent beams (θ_x≈5°～10° and θ_y≈20°～35° ), i.e., their poor beam quality. In order to improve the beam quality of laser diode arrays, special optical systems have to be used to reshape the asymmetric divergent beams. One most simple and effective beam-reshaping way is to change linearly arranged laser beams of the one-dimension laser diode array (LD Bar) into circularly arranged laser beams by fiber arrays. With flat-end fiber arrays, the coupling efficiency is usually about 20%, which is obviously too low to use in most situations. So, fiber arrays with special ends have to be prepared to obtain both high coupling efficiency and high beam quality output of LD Bar. By ray tracing method, theoretically studied that the coupling properties of three kinds of specially prepared fiber arrays with LD Bar were theoritically studied. The results show that, compared with the sphere-end fiber and the tapered fiber, the sphere-end tapered fiber having much higher coupling efficiency (over 90%) with LD Bar was optimized. Moreover, when the sphere-end tapered fiber array is in use, output beams of LD Bar with much higher quality can be obtained due to the strong suppression of divergent angles. The sphere-end tapered fibers are easily prepared in experiment by methods of high-temperature melting and chemical erosion.