Determination of Nonlinear Optical Coefficients of KBe₂BO₃F₂ Crystals

Considering that KBe₂BO₃F₂ (KBBF) is an outstanding deep ultraviolet crystal which can generate the shortest wavelengths in second harmonic generation and sum-frequency generation, we report the determination of the nonlinear optical coefficients of the KBBF crystal. The d₁₁ coefficient was determined to be 0.49 pm/V by the Maker fringes method at the wavelength 1064 nm, which is in agreement well with the theoretical value.