Patent ID: 6278548
Filing Date: 2001-08-21
Classification: B82Y,G02B,G11B

Abstract:
A diffraction grating, for diffracting a coherent polarized incident light beam, said incident light beam having first and second polarized components, comprising:a plurality of light transmitting mediums forming an asymmetrical optical grating pattern, wherein at least one of the mediums has a refractive index that is different dependent on first and second polarizing directions of the incident light beam to generate separated .+-.nth order diffracted light beams from each said first and second polarized incident light beam components, where n is a natural number;in a sectional plane perpendicular to a direction along said grating pattern, said grating pattern having a staircase shape boundary line between said mediums with a width of respective stages of said staircase shape being varied;said grating pattern having a diffraction efficiency of +nth order diffracted light of the first polarized light beam component that is larger than a diffraction efficiency of -nth order diffracted light of said first polarized light beam component by an amount hat is sufficient to detect a magneto-optical signal from +nth order diffracted light and -nth order diffractive light; andsaid grating pattern having a diffraction efficiency of +nth order diffracted light of the second polarized light beam component that is smaller than a diffraction efficiency of -nth order diffracted light of said second polarized light beam component by an amount that is sufficient to detect a magneto-optical signal from +nth order diffracted light and -nth order diffracted light.