Patent ID: 6859305

Claim:
A prism-nonlinear optical crystal coupler for laser frequency conversion, the prism-nonlinear optical crystal coupler comprising: a nonlinear optical crystal and a coupling prism, the coupling prism being provided on at least one of an incident surface and an exit surface of the nonlinear optical crystal, an apex angle θ of the coupling prism on the incident surface being determined by the refractive index of the coupling prism and a phase-matching angle of the nonlinear optical crystal; for a given wavelength the apex angle θ being determined by n 3 sin θ 2 =n 1 sin θ pm, θ 1 +θ 2 =θ, sin α=n 3 sin θ 1 , where 1 is a refractive index of the crystal at the given wavelength, n 3 is a refractive index of the prism at the given wavelength, α is an incident angle of a laser beam at the coupling prism, θ pm is a phase-matching angle of the nonlinear optical crystal at the given wavelength, θ 1 is a refractive angle of the laser beam into the prism, θ 2 is an incident angle of the laser beam from the prism to the crystal, so that the beam is incident at an incident angle of substantially 0° to satisfy the phase-matching angle in the crystal; a fundamental beam and a second harmonic beam being separated through the coupling prism at the exit surface.