Frequency doubling coefficient is a basic parameter of nonlinear optical crystals, so it is necessary to measure its frequency doubling coefficient for every useful nonlinear optical crystal. Mark fringe method is an important method for experimental measurement of frequency doubling coefficient of nonlinear optical crystals. In this paper, the Mark fringes of a series of nonlinear optical crystals are measured by this method, and compared with the standard KDP crystals, and the frequency doubling coefficients of these crystals at the wavelength of 1064.2nm are obtained. This paper * * * includes the following main contents: (1) Introduction. This is the basic part of this paper, which briefly introduces the basic theory of nonlinear optics, gives some formulas used to deal with Maker fringes, and finally summarizes nonlinear optical crystals.
(2) Measurement theory of frequency doubling coefficient of nonlinear optical crystals. In this part, the phase matching method and Mark fringe method commonly used in measuring frequency doubling coefficient are introduced in detail, and the two methods are compared, and the matters needing attention in measurement are pointed out.
(3) Measurement of frequency doubling coefficient of 3)LBO crystal. Firstly, the original measurement system is improved, especially the linear region of photomultiplier tube is optimized, thus greatly improving the measurement accuracy. Then the frequency doubling coefficients of LBO, CBO and CLBO crystals are measured with the improved system, and compared with the previous measured values.
Research on frequency doubling performance of RBBF family crystals, including KBBF and RBBF crystals. In this paper, their type ⅰ and type ⅱ interference fringes are measured. In view of the fact that the refractive index dispersion equation of RBBF crystal has not been fitted at present, this paper refers to the refractive index dispersion equation of KBBF and the white refractive index of RBBF, and obtains the refractive index values of RBBF at 1064.2nm and 532. 1nm by numerically fitting the phase matching angle of RBBF, and then calculates the frequency doubling coefficients of these two crystals.
(5) Measurement of frequency doubling coefficient of 5)BPO crystal. The ultraviolet absorption edge wavelength of BPO is very short, which can be used to obtain deep ultraviolet coherent light source. In this paper, the frequency doubling coefficient is measured by Mark fringe method, which provides an important reference for further research.