Nonlinear Optics Calculator
Calculate phase-matching angles and SHG conversion efficiency for nonlinear optical crystals.
Second-harmonic generation (SHG) requires both phase matching — equalizing the phase velocities of the fundamental and harmonic beams — and sufficient nonlinear coupling to achieve useful conversion efficiency. Phase matching determines the crystal cut angle at which the ordinary and extraordinary refractive indices satisfy the momentum-conservation condition; walk-off angle and effective nonlinearity d_eff follow from that angle. The tool supports two modes: phase-matching angle calculation for BBO, KDP, KTP, and LBO using material Sellmeier coefficients, and SHG conversion efficiency estimation using the undepleted-pump approximation, including PPLN. Inputs include fundamental wavelength, phase-matching type (Type I or II), crystal length, and peak intensity. Biaxial crystals display principal indices only and flag that full optimization requires a dedicated solver.