Blue light production by type-I non-critical phase matching second-harmonic generation in La(Ca1−xSrx)4O(BO3)3 single crystals

Abstract

The optical birefringence of La(Ca_1−xSr_x)₄O(BO₃)₃ nonlinear optical crystals can be controlled by changing the compositional parameter x. Therefore, it is possible to achieve non-critical phase matching (NCPM) for type-I second-harmonic generation (SHG) of specific wavelengths in the range of 990 to at least 946 nm. La(Ca_1−xSr_x)₄O(BO₃)₃ single crystals (with x = 0.0, 0.1, 0.3 and 0.4 starting compositions) of large size and good optical quality were grown by the Czochralski method. X-ray diffraction measurements have been carried out to characterize the structural changes with compositional parameters x. The NCPM wavelengths along the Z-axis were experimentally determined for each grown crystal. According to our assumptions, the obtained results demonstrate that by an appropriate choice of the compositional parameter x in La(Ca_1−xSr_x)₄O(BO₃)₃ crystals, we can obtain blue light in the range of 495–473 nm through type-I NCPM SHG of the corresponding fundamental wavelengths, which are very attractive for practical applications.