Patent ID: 6717731
Filing Date: 2004-04-06
Classification: G02B,H04B

Abstract:
An apparatus comprising:a virtually imaged phased array (VIPA) generator receiving an input light at a respective wavelength and producing a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light; and a reflecting surface reflecting the output light back to the VIPA generator; a lens or mirror focusing the output light traveling from the VIPA generator onto the reflecting surface so that the reflecting surface reflects the output light, the reflected light being directed by said lens or mirror back to the VIPA generator, the reflecting surface being movable in or around a focal plane of the lens or mirror; wherein the reflecting surface has different curvatures at different positions along a direction perpendicular to a plane which includes the traveling directions of collimated output light from the VIPA generator for input light at different wavelengths, curvature c(y) of the reflecting surface being as follows: c&it;(y)=K8&it;f4&it;y4+K&it;â€ƒ&it;Î˜2&it;f3&it;y3+K&it;â€ƒ&it;Î˜2-(f-a)2&it;f2&it;y2wherey=is a light focusing position on the reflecting surface, &THgr;=is an input angle of the input light to the VIPA generator in air, f=is a focal length of the lens or mirror, a=is a depth of a center beam waist of the VIPA generator, and K is a constant so that chromatic dispersion equals âˆ’2n4K/c&lgr;, with c being the speed of light, &lgr; being wavelength, and n being a refractive index of material forming the VIPA generator.