Patent ID: 6384973
Filing Date: 2002-05-07
Classification: G02B,G02F

Abstract:
An apparatus for optical frequency conversion using a specially cut uncoated birefringent crystal with a primary optical axis along the X direction wherein a first infrared input wavelength and a second infrared input wavelength polarized along the Z axis combine within the birefringent crystal by the sum-frequency process to generate a third, visible wavelength polarized along the Y axis, said apparatus comprised of:a birefringent crystal having an infrared input end comprised of a first lower triangular-shaped Brewster cut surface cut for Z-polarization transmission and a first upper inverted triangular-shaped Brewster cut surface cut for Y-polarization transmission and an infrared output end comprised of a second lower Brewster cut surface cut for Z-polarization transmission and a second upper surface cut perpendicular to the second lower Brewster cut surface; an input coupler prism having a normal input face with anti-reflection coatings for the IR wavelengths and a Brewster cut output face cut for Z-polarized wavelengths positioned adjacent to the birefringent crystal first lower Brewster cut surface; and an output coupler prism having an input Brewster surface cut for Z-polarization transmission and anti-reflection coatings matched to the infrared input wavelengths and a high-reflection coating matched to the visible wavelength and positioned adjacent to the second lower Brewster cut surface, and having an anti-reflection coated output face, whereby the infrared wavelengths pass into and out of the lower part of the birefringent crystal along the X-axis and generate the visible wavelength by the sum-frequency process, which visible wavelength is reflected at the second lower Brewster cut surface and at the second upper surface and passes out of the birefringent crystal at the first upper Brewster cut surface.