Grating structure for splitting light
AssigneesToyota Motor Engineering & Manufacturing North America, Inc., The Trustees of the University of Pennsylvania
InventorsHideo Iizuka, Nader Engheta
Life of this patent
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Abstract
A grating structure for splitting light. The grating structure including alternating ridges and grooves. The ridges and grooves are configured such that the grating directs p-polarization components of incident light to the −1st order diffraction mode and s-polarization components of incident light to the 0th order diffraction mode.
Claims17
A grating structure comprised of a fused silica base, the fused silica base having alternating ridges and grooves, the ridges and grooves forming a fused silica to air interface, the grating having a ratio of the effective refractive index difference of p-polarization to the effective refractive index difference of s-polarization, where the numerator of the ratio is an odd number and the denominator of the ratio is an even number, thereby directing p-polarization components of incident light to the −1st order diffraction mode and s-polarization components of incident light to the 0th order diffraction mode, where the incident light has an incident angle θin of between about 30° and 45° and a wavelength λ=350−1600 nm.
A grating structure comprised of a base, base having alternating ridges and grooves, the ridges and grooves forming a ratio of the effective refractive index difference of p-polarization to the effective refractive index difference of s-polarization directing p-polarization components of incident light to the −1st order diffraction mode and s-polarization components of incident light to the 0th order diffraction mode, where the incident light has an incident angle θin of between about 30° and 45° and a wavelength λ=350-1600 nm.
A method of splitting an unpolarized light beam comprising:
- providing a grating;
- providing an unpolarized light beam at an incident angle between about 30° and 45°;
- splitting the unpolarized light beam such that p-polarization components of incident light to the −1st order diffraction mode and s-polarization components of incident light to the 0th order diffraction mode, wherein the grating has a ratio of the effective refractive index difference of p-polarization to the effective refractive index difference of s-polarization, where the numerator of the ratio is an odd number and the denominator of the ratio is an even number.
A method of producing a grating structure comprising:
- defining a wavelength;
- defining an incidence angle;
- determining a grating period based on a Littrow mounting condition;
- determining the relationship between the effective refractive index and the fill factor;
- identifying a fill factor where the ratio between the effective refractive index difference of p-polarization to the effective refractive index difference of s-polarization is about 1/2;
- determining the height of the grating;
- etching the grating based on the grating period, fill factor, and height.
Dependencies are inferred from the claim text.