Almost all attention has been paid to the effective nonlinear coefficient along the direction of phase matching, so this paper calculated the omnidirectional effective nonlinear coefficient of ReCOB single crystals by computer out of interest. The results showed that the distribution of the first and second quadrants of omnidirectional |deff| presented multi-peaks surface divided by three “valleys” which were made up of a series of minimum values. The variation of d32 and d13 had more significant impacts on the distribution of omnidirectional |deff| than the other coefficients and the variation of wavelength had negligible influence on that. A broadband wavelength range about 6 nm could achieve efficient frequency conversion simultaneously within the deviation being less than 2 degrees during a type-I DFG process in YCOB crystal. These results could provide valuable guidance for the selection and utilization of ReCOB crystals.
YCa4O(BO3)3 (YCOB) was found to have a large temperature bandwidth in XZ optical principal plane. By considering the thermal rotation effect, the temperature bandwidth in spatial directions were studied by theoretical derivation and frequency doubling experiments. The temperature bandwidth in maximum effective nonlinear optical coefficient (deff) direction was not as big as that in (30.8°, 180°) direction. The light propagate in the second quadrant was found to have bigger temperature bandwidth than the first quadrant. And the temperature bandwidth was found to change as the wavelength change of fundamental frequency light.