Devices based on an array of light-filtering channels with surface plasmon interference filters

• US 6,992,826 B2
• Filed: 09/25/2001
• Issued: 01/31/2006
• Est. Priority Date: 09/02/1997
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Wang, Yu
• Primary Examiner(s): Boutsikaris, Leonidas
• Application Number:
  US09/965,033
• Publication Number:
  US 20020036828A1
• Time in Patent Office: 1,589 Days
• Field of Search: 359577-580, 359584-585, 359/582, 359/589, 349105-106, 345/88, 348/744
• US Class Current: 359/585
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: G02F 1/195 by using frustrated reflection digital reflection using controlled total internal reflection G02F1/315
• CPC Class Codes: G02F 2203/10 plasmon

Abstract

Devices based on surface plasmon filters having at least one metal-dielectric interface to support surface plasmon waves. A multi-layer-coupled surface plasmon notch filter is provided to have more than two symmetric metal-dielectric interfaces coupled with one another to produce a transmission spectral window with desired spectral profile and bandwidth. Such notch filters can form various color filtering devices for color flat panel displays.

Claims

1. A device, comprising:

a plurality of layers stacked over one another to form a layered structure which supports a two-dimensional array of light-filtering channels, wherein each layer is structured to have an one-dimensional array of light-filtering channels,

wherein the two-dimensional array of light-filtering channels comprises an input surface from which said light-filtering channels receive input light and an output surface from which said light-filtering channels export output light, and wherein each light-filtering channel comprises;

a light-conducting channel formed of a transparent dielectric material having a first surface which is substantially reflective and a second surface opposing said first surface, said first and second surfaces substantially parallel to said light-conducting channel; and

at least two optical filters sequentially formed on said second surface along said light-conducting channel to reflected said input light between said first and second surfaces so that said input light is sequentially reflected and filtered by said optical filters to produce said output light, wherein each optical filter includes at least one metal layer and an electro-optical dielectric layer contacting with each other to form a metal-dielectric interface which generates a surface plasmon wave in response to a p-polarized input light beam to transmit light at a selected wavelength within a bandwidth according to a control voltage from said metal layer to said dielectric layer and reflects light of other wavelengths; and

at least two thin-film transistors respectively formed on said optical filters to provide said control voltage to control a refractive index of said dielectric layer and thereby said selected wavelength to change a color and a gray scale of said output light.

2. The device as in claim 1, wherein said dielectric layer includes a liquid crystal material.

3. The device as in claim 1, further comprising a screen positioned relative to said output surface to receive said output light from said light-filtering channels to form an image.

4. The device as in claim 1, wherein said input surface is substantially parallel to said output surface, and wherein said input and output surfaces each form an angle with respect to said first and second surfaces in each light-filtering channel.

5. The device as in claim 1, further comprising a polarization element that receives and transmits input light to said input surface.

6. A device, comprising:

a plurality of transparent plates each having a filtering surface and an opposing, reflecting surface, a metallic layer formed over said filtering surface of each transparent plate;

an electro-optical dielectric layer, whose refractive index changes in response to a control voltage, disposed in contact with said metallic layer to form a metal-dielectric interface which generates a surface plasmon wave in response to a polarized input light beam to transmit light through said metallic layer at a selected wavelength within a bandwidth according to a local refractive index of said electro-optical dielectric layer at each location of said metallic layer where light is reflected and to reflect light of other wavelengths back to each transparent plate; and

a plurality of parallel linear arrays of transistors formed over said dielectric layer, wherein said transistors are independent from one another, and where each parallel linear array of transistors defines a light channel along which light is reflected between said filtering and said reflecting surfaces via at least two locations on the filtering surface with two transistors sequentially located along the light channel to modify a color and an intensity of said light according to voltages from said transistors in each linear array relative to a common voltage of said metallic layer,

wherein said transparent plates are stacked over one another so that a reflecting surface of one transparent plate faces a filtering surface of an adjacent transparent plate to form a two-dimensional array o light channels.

7. The device as in claim 6, further comprising a first intermediate metallic layer in contact with said electro-optical material layer and a first electro-optical material layer switched between said first intermediate metallic layer and said plurality of parallel linear arrays of transistors.

8. The device as in claim 6, wherein said transistors are thin-film transistors.

9. The device as in claim 6, wherein each transparent plate is formed of a glass material.

10. The device as in claim 6, wherein said electro-optical dielectric layer includes a liquid crystal material.

11. A method, comprising:

providing a plurality of plates each comprising a dielectric material layer having a first reflective surface and a second, opposing metallic surface;

patterning the second metallic surface to include a two-dimensional array of separate metallic areas, a plurality of metal-dielectric interfaces on each separate metallic area, and thin-film transistors above the metal-dielectric interfaces respectively on the separate metallic areas;

stacking and bonding the plates over one another to form a composite structure; and

slicing the composite structure into a plurality of panels of two-dimensional light-filtering channels where each panel includes a portion of the stacked plates and each portion in each plate includes at least three separate metallic areas as three independent surface filters along a direction that is perpendicular to a direction of the slicing and defines a light-filtering channel wherein light incident to one of the light-filtering channels of the plate is sequentially reflected and filtered by the three surface plasmon filters to produce a filtered optical output on the side of the plate.

12. The method as in claim 11, further comprising:

providing independent electric controls to separate metallic areas in one sliced panel; and

controlling voltages applied to the independent electrical controls to control light intensities and colors of output light from the light-filtering channels for light entering from one side of the panel and exiting on an opposite side of the panel.