Broadband wire grid polarizer for the visible spectrum

A broadband wire grid polarizer for the visible spectrum, the polarizer comprising:

• a transparent substrate having a first surface and a refractive index;
• an array of parallel, elongated elements supported by the substrate;
• and
• a region disposed between the elements and the substrate having a refractive index which is less than the refractive index of the substrate, and having a thickness of between approximately 0.001 and 0.3 .mu.m.

An apparatus for polarizing broad bandwidth, visible light, the apparatus comprising:

• a light source producing a light beam having at least one wavelength within the visible spectrum;
• a transparent substrate disposed in the light beam having a first surface and a refractive index;
• an array of parallel, elongated elements coupled to the first surface of the substrate;
• and
• a region disposed between the first surface of the substrate and the elements, the region having a refractive index which is less than the refractive index of the substrate;
• and
• wherein the array of elements is configured to interact with the electromagnetic waves of the light in the visible spectrum to generally reflect most the light of a first polarization and transmit most the light of a second polarization;
• and
• wherein the array has a configuration and the elements have a size which would normally create a resonance effect in combination with the substrate within the visible spectrum in which a significant amount of the second polarization is reflected rather than transmitted;
• and
• wherein the region with a lower refractive index than the substrate refractive index causes a shift of the normally occurring resonance effect to a lower wavelength, thereby broadening a band of visible wavelengths in which no resonance effect occurs.

A broadband wire grid polarizer, the polarizer comprising:

• a transparent substrate having a first surface and a refractive index;
• an array of parallel, elongated elements supported by the first surface of the substrate, wherein the array satisfies the condition 0.19.lambda..ltoreq.p.ltoreq.2.lambda., where p is the period of the elements, and .lambda. is the wavelength;
• and
• a region disposed between the first surface of the substrate and the elements, the region having a refractive index and a thickness between the first surface of the substrate and the elements, wherein the region satisfies the conditions n.sub.R <n.sub.S and 0.001 .mu.m.ltoreq.t.sub.R .ltoreq.0.3 .mu.m, where n.sub.R is the effective refractive index of the region, n.sub.S is the refractive index of the substrate, and t.sub.R is the thickness of the region between the first surface of the substrate and the elements.

A method for making a broadband wire grid polarizer for the visible spectrum, the method comprising:

• providing a transparent substrate with a first surface and a refractive index;
• forming an array of parallel elements on the first surface of the substrate, the elements defining a mask;
• and
• etching the substrate between the elements to create ribs that extend from the substrate and which define a region with a refractive index less than the refractive index of the substrate.

A method for making a broadband wire grid polarizer for the visible spectrum, the method comprising:

• providing a transparent substrate with a first surface and a refractive index;
• depositing a layer of dielectric film on the first surface with a refractive index less than the refractive index of the substrate;
• forming an array of parallel elements on the layer of dielectric film;
• and
• etching the layer of dielectric film between the elements to create ribs.

A broadband wire grid polarizer for the visible spectrum, the polarizer comprising:

• a transparent substrate having a first surface and a refractive index;
• an array of parallel, elongated elements supported by the substrate and having a thickness of between approximately 0.04 and 0.3 .mu.m, the elements being aluminum or silver;
• and
• a region disposed between the elements and the substrate having a refractive index which is less than the refractive index of the substrate.

A broadband wire grid polarizer for the visible spectrum, the polarizer comprising:

• a substrate having a first surface and a refractive index;
• a region on the first surface of the substrate including a plurality of ribs extending from the substrate and having a refractive index which is less than the refractive index of the substrate;
• and
• an array of parallel, elongated elements disposed on the region.

A broadband wire grid polarizer for the visible spectrum, the polarizer comprising:

• a substrate having a first surface and a refractive index;
• a region on the first surface of the substrate having a refractive index which is less than the refractive index of the substrate, the region including at least one layer of material different from the material of the substrate, and a plurality of ribs formed in and extending from the film layer;
• and
• an array of parallel, elongated elements disposed on the region.

A broadband wire grid polarizer for the visible spectrum, the polarizer comprising:

• a substrate having a first surface and a refractive index;
• a region on the first surface of the substrate having a refractive index which is less than the refractive index of the substrate, and having a plurality of ribs formed in and extending from the substrate;
• at least one layer of material different from the material of the ribs disposed on each of the plurality of ribs;
• and
• an array of parallel, elongated elements disposed on the region.