大功率VCSEL器件的空间相干性的研究（英文）

Research on the Spatial Coherent Characteristics of High Power VCSEL

由Van Cittert-Zernike提出的部分相干光定理出发,研究了大功率垂直腔面发射激光器（VCSEL）及其列阵器件的空间相干特性。采用杨氏双缝干涉实验装置得到980nm波段VCSEL单管器件的干涉条纹图样,再将干涉图样转换进行灰度读取处理得到光强分布图样,最后分别采用积分法和平均值法对光强图样进行计算,所得结果与由Van Cittert-Zernike定理所得的空间相干度理论值进行对比,并讨论了VCSEL器件发光孔径对其空间相干度的影响。实验结果表明提出的积分法计算出的空间相干度与理论值的误差在2.5%37.4%。而常用的平均值法所得结果与理论值的误差为7.5%120.5%。可见,传统算法误差普遍大于积分算法1.527倍。出光孔径在200500μm的单管VCSEL器件相干度在0.731-0.426之间,且发光孔径越小,其相干度越大。分析了积分平均值法和传统平均值法的优劣及VCSEL器件出光孔径对相干特性的影响,为VCSEL相干列阵的设计提供了必要的理论和实验依据。

The spatial coherence properties of high power vertical cavity surface emitting lasers （VCSELs） are studied based on the theorem of partially coherent light proposed by Van Cittert-Zernike. The interference stripe patterns are gauged using the Young＇s double-slit experiment for the devices of 980 nm wavelength VCSEL single emitters. Then interference patterns are switched to grayscale by intensity distribution patterns for data collection. In this paper, the integral average value method is proposed to calculate the degree of spatial coherence. The proposed integral average value method and traditional average method are used respectively to calculate the light intensity of the pattern. The results are compared with those calculated by the theoretical value of Van Cittert- Zernike theorem. The VCSEL optical apertures influence on coherent characteristics are also discussed. The experimental results show that, a relative error within 2. 5% - 9.4% is reached by our integral average value method. On the contrary, a relative error of 7. 5% - 67. 4% are got from the traditional average method. Apparently, traditional average value method causes the error generally 1. 5 - 27 times worse than our integral average value method. Moreover, for single emitter VCSELs with optical aperture from 200 μm to 500 μm, the smaller the optical aperture are, the larger the coherent degrees （between 0. 731 -0. 426） are. The conclusion can be wildly used on theoretical and experimental design for VCSEL coherent arrays.