Patent ID: 6661830
Filing Date: 2003-12-09
Classification: H01S

Abstract:
A mirror for reflecting and transmitting light at respectively first and second different wavelengths, the second wavelength being shorter than the first wavelength, the mirror, comprising:a membrane peripherally supported on a substrate over an aperture therein; said membrane including a grating on a surface thereof, said grating including a regular array of spaced-apart parallel strips of a first material surmounting at least one optical interference layer of uniform thickness, said grating strips having a width and a height and said grating having a grating period defined as the distance between adjacent ones of said parallel strips, said grating period being less than the second wavelength, wherein the composition and thickness of said first material and said interference layer, the width and height of the grating and the ratio between said grating width and period, are selected such that: a. first wavelength light that is normally incident on said mirror has different specular reflectivities in first and second polarization planes oriented respectively parallel and perpendicular to said grating strips; and b. the transmissivity of said mirror is greater than 50% for second-wavelength light in any one of said polarization orientations.