Switchable polymer-dispersed liquid crystal optical elements

• US 7,265,882 B2
• Filed: 11/08/2005
• Issued: 09/04/2007
• Est. Priority Date: 07/12/1996
• Status: Expired due to Fees

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Sutherland, Richard L., Kelly, William J., Epling, Bob, Hagan, William K.
• Primary Examiner(s): LAVARIAS, ARNEL C
• Application Number:
  US11/268,660
• Publication Number:
  US 20060119914A1
• Time in Patent Office: 665 Days
• Field of Search: None
• US Class Current: 359/15
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• CPC Class Codes: G02F 1/31 Digital deflection, i.e. optical switchingG02F1/33 takes precedence
• CPC Class Codes: G02F 2201/346 distributed (Bragg) reflector
• CPC Class Codes: G02F 2203/05 wavelength dependent
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G02F 2203/585 Add/drop devices
• CPC Class Codes: G03H 1/02 Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 2001/026 Recording materials or recording processes G03H2226/11 takes precedence; corresponding details, see subgroups of G03H2260/00
• CPC Class Codes: G03H 2001/0264 Organic recording material
• CPC Class Codes: G03H 2001/2231 Reflection reconstruction
• CPC Class Codes: G03H 2001/2234 Transmission reconstruction
• CPC Class Codes: G03H 2260/12 Photopolymer
• CPC Class Codes: G03H 2260/33 Having dispersed compound

Abstract

Transmission and reflection type holograms may be formed utilizing a novel polymer-dispersed liquid crystal (PDLC) material and its unique switching characteristics to form optical elements. Applications for these switchable holograms include communications switches and switchable transmission, and reflection red, green, and blue lenses. The PDLC material offers all of the features of holographic photopolymers with the added advantage that the hologram can be switched on and off with the application of an electric field. The material is a mixture of a polymerizable monomer and liquid crystal, along with other ingredients, including a photoinitiator dye. Upon irradiation, the liquid crystal separates as a distinct phase of nanometer-size droplets aligned in periodic channels forming the hologram. The material is called a holographic polymer-dispersed liquid crystal (H-PDLC).

Claims

1. A crossbar switch comprising:

multiple polymer-dispersed liquid crystal holographic elements, wherein each of the polymer-dispersed liquid crystal holographic elements deflects light in a first state and transmits light in a second state, and further wherein the multiple polymer-dispersed liquid crystal holographic elements may be arranged to form an N²×

N² matrix cross-connect switch, where N equals at least two, the cross-connect switch including multiple layers each comprised of N×

N elements, the layers being arranged in sets, each set containing N layers, in a first set of N layers each element therein is capable of deflecting light in one of the up or down direction and in a second set of N layers each element therein is capable of deflecting light in one of the right or left direction.

2. The crossbar switch of claim 1, wherein within at least one layer there is at least one row or column comprised of a sublayer of sub-elements, the number or type of sub-elements in the sublayer varying from the number or type of elements in each the remaining rows or columns within the at least one layer.

3. The crossbar switch of claim 1, the number of sub-elements in the sublayer being twice the number of elements in each of the remaining rows or columns within the at least one layer.

4. The crossbar switch of claim 1, the sub-elements being holes containing no polymer-dispersed liquid crystal holographic element.