Temperature and angular widths of the phase-matching curve of a lithium niobate crystal

The results are given of a calculation of the temperature and angular widths of the phasematching curve as a function of the phase-matching angle in the generation of a second harmonic in a lithium niobate crystal. It is shown that the angular width increases with the phase-matching angle, whereas the temperature width remains constant. The experimental results obtained for helium–neon laser radiation (λ = 1152 nm) are in good agreement with the results of the calculations.