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中国物理学会期刊

谐振腔内的高质量圆对称艾里光束的产生方法

CSTR: 32037.14.aps.69.20191088

Generation of high-quality circular Airy beams in laser resonator

CSTR: 32037.14.aps.69.20191088
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  • 本文提出一种在谐振腔内产生高质量圆对称艾里光束的方法, 通过使用针对特定参数光束设计的衍射光学元件替代反射腔镜, 可在腔内获得所需的特定参数光束. 研究结果表明, 该方法产生的圆对称艾里光束的参数可控; 模式能量损耗低, 接近高斯基模光束; 光束质量高, 明显优于目前常用的傅里叶空间纯相位全息编码法. 接着, 讨论了组装系统时产生的腔长误差和同轴度误差, 以及加工衍射元件时产生的刻蚀误差对产生光束的影响. 结果表明, 现有的机械调节技术和微纳加工技术, 完全能满足系统误差的精度要求, 显示该方法对误差有较好的容差性.

     

    A scheme for forming high-quality circular Airy beams inside the laser resonator is presented theoretically. The desired circular Airy beam can be generated when the common reflective mirror is replaced by a designed diffractive optical element. The mode generated in the proposed cavity can be stimulated by using the so-called eigenvector method. The calculated results show that the parameters of the beams can be controlled by changing the phase distribution of the diffractive optical element. The loss of the generated mode is very low, which is close to that of the fundamental Gaussian mode. The purity of the generated mode is very high, which is much better than that from the phase-only encoding method in Fourier space. The phase distribution of the diffractive optical element needs designing for a fixed resonator length. In practice, the real resonator length may not be equal to the designed resonator length. Thus, the influence of the alignment error of the resonator length is discussed in detail. The results show that the diffraction loss of the proposed system is still very small even when the error reaches up to 2 mm. Meanwhile, the purity of the generated mode decreases little. Then, the influence of etching depth errors and the decenter of the reflective mirrors are discussed in detail. Here we assume that the fluctuations are randomly distributed. The value of the maximum fluctuation is used to represent the etching depth error degree. The results show that the diffraction loss of the proposed system is more sensitive to production error, and the purity of the generated mode is more sensitive to alignment error. Thus, we estimate that the maximum etching depth error should be less than six percent of the wavelength, and the vertical distance between the centers of the two reflective mirrors should be less than 7 μm if one wants to obtain high-quality CAB with high efficiency. The requirements for precision are acceptable for existing microfabrication and operation technologies.

     

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