Bistable liquid crystal light-modulating device

Abstract

A bistable liquid crystal spatial light modulating (SLM) device (SLM) device utilizes the homeotropic and bubble domain texture change of a cholesteric liquid crystal that is responsive to external stimuli, such as electric voltage, light and pressure. The SLM device is configured to be switched between the two stable textures of the bubble domain texture or the fingerprint texture. In addition, the SLM device may be switched between transparent and light-scattering states by the application of an electric field, light irradiation or physical/mechanical pressure. The light transmission state and the light-scattering states of the present invention are also stable in time at zero voltage, and are reversible upon the application of an external field at a different voltage, frequency or wavelength of light.

What is claimed is: 
     
         1 . A method of modulating light comprising the steps of:
 providing a light modulating device that includes a pair of at least partially light transparent electrodes, such that each electrode has a homeotropic alignment layer disposed thereon, wherein a mixture that includes nematic liquid crystal material and a chiral dopant is disposed in a gap formed between said homeotropic alignment layers, applying a voltage to at least one of said electrodes;   changing an optical state of said light modulating device from a homeotropic state to a different state that includes one of a bubble domain (BD) state, a dynamic light scattering (DS) state, or a finger print (FP state in response to said applied voltage; and   removing said applied voltage, wherein said different optical state remains stable.   
     
     
         2 . The device of  claim 1 , wherein each said homeotropic alignment layer is formed of polyimide. 
     
     
         3 . The device of  claim 1 , wherein said mixture further includes a light-absorbing moiety. 
     
     
         4 . The device of  claim 1 , wherein said mixture further includes a polymeric material. 
     
     
         5 . The device of  claim 1 , wherein said electrodes are flexible. 
     
     
         6 . The method of  claim 1 , further comprising:
 applying said voltage to at least one of said electrodes;   changing said optical state of said light modulating device from said different state to said homeotropic state; and   removing said voltage, wherein said homeotropic state remains stable.   
     
     
         7 . The device of  claim 6 , wherein said mixture further includes a light-absorbing moiety. 
     
     
         8 . The device of  claim 6 , wherein said mixture further includes a polymeric material. 
     
     
         9 . The device of  claim 6 , wherein said first and second electrodes are flexible. 
     
     
         10 . A method of modulating light comprising:
 providing a light modulating device that includes a pair of at least partially light transparent layers, such that each layer has an alignment layer disposed thereon, wherein a mixture that includes nematic liquid crystal material and a chiral dopant is disposed in a gap formed between said alignment layers;   applying a stimulus to said material;   changing, in response to said stimulus, said optical state of said material from a first stable state to a different stable state that includes one of a bubble domain (BD) state, a dynamic light scattering (DS) state, or a finger print (FP) state; and   removing said stimulus, wherein said different state remains stable.   
     
     
         11 . The method of  claim 10 , wherein said stimulus is one of an electric field, a deformation force, or light. 
     
     
         12 . The method of  claim 10 , wherein said first stable state comprises a homeotropic state. 
     
     
         13 . The method of  claim 10 , further comprising:
 applying said stimulus to said material;   changing, in response to said stimulus, said optical state of said material from said different stable state to said first stable state; and   removing said external stimulus, wherein said first stable state remains stable.   
     
     
         14 . The method of  claim 13 , wherein said stimulus is one of an electric field, a deformation force, or light.