Sensitive control of broad-area semiconductor lasers by cavity shape
Sensitive control of broad-area semiconductor lasers by cavity shape
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DOI：
10.1063/5.0087048
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发表时间：
2022-01
期刊：
影响因子：
5.6
通讯作者：
Kyungduk Kim;S. Bittner;Yuhao Jin;Yongquan Zeng;S. Guazzotti;O. Hess;Qi Jie Wang;H. Cao
中科院分区：
文献类型：
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作者：
Kyungduk Kim;S. Bittner;Yuhao Jin;Yongquan Zeng;S. Guazzotti;O. Hess;Qi Jie Wang;H. Cao
光学腔的射线动力学表现出分岔点：射线轨迹在稳定和不稳定之间突然切换的特殊几何形状。一个突出的例子是具有两个平面反射镜的法布里-珀罗腔，它被广泛应用于广域半导体激光器。这样的腔支持激光在相对较少的横向模式，激光是高度敏感的灯丝和不规则的脉动。在这里，我们通过实验证明，稍微偏离这个分岔点（平面腔）就会极大地改变激光器的性能。在具有两个凹面镜的近平面腔中，横向激光模式的数量急剧增加。虽然激光发射的空间相干性降低，但输出光束的发散角仍然相对较窄。此外，与法布里-珀罗腔相比，时空激光动力学变得更加稳定。我们的近平面广域半导体激光器具有更高的亮度，更好的方向性，因此可以比白炽灯更短的集成时间，同时具有足够低的散斑对比度，使其成为无散斑成像的卓越光源。此外，我们的方法在分岔点附近具有极高的灵敏度控制时空动力学，可以应用于其他类型的高功率激光器和非线性动态系统。
The ray dynamics of optical cavities exhibits bifurcation points: special geometries at which ray trajectories switch abruptly between stable and unstable. A prominent example is the Fabry–Perot cavity with two planar mirrors, which is widely employed for broad-area semiconductor lasers. Such cavities support lasing in a relatively small number of transverse modes, and the laser is highly susceptible to filamentation and irregular pulsations. Here, we demonstrate experimentally that a slight deviation from this bifurcation point (planar cavity) dramatically changes the laser performance. In a near-planar cavity with two concave mirrors, the number of transverse lasing modes increases drastically. While the spatial coherence of the laser emission is reduced, the divergence angle of the output beam remains relatively narrow. Moreover, the spatiotemporal lasing dynamics becomes significantly more stable compared to that in a Fabry–Perot cavity. Our near-planar broad-area semiconductor laser has higher brightness, better directionality, and hence allows shorter integration times than an incandescent lamp while featuring sufficiently low speckle contrast at the same time, making it a vastly superior light source for speckle-free imaging. Furthermore, our method of controlling spatiotemporal dynamics with extreme sensitivity near a bifurcation point may be applied to other types of high-power lasers and nonlinear dynamic systems.