Switchable polymer-dispersed liquid crystal optical elements
View Patent ↗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).
1. An optical connector comprising:
a first matrix comprising N×N polymer-dispersed liquid crystal switchable holographic components for deflecting and transmitting incident radiation, wherein each of the holographic components is capable of rotation about its normal axis, further wherein N equals at least 2; and
a second matrix comprising N×N optical components for accepting the deflected and transmitted incident radiation from each of the N×N optical components in the first matrix.
2. The optical connector according to claim 1 , wherein each of the N×N polymer-dispersed liquid crystal switchable holographic components is capable of deflecting incident radiation in each one of the following directions:
(a) up;
(b) down;
(c) right; and
(d) left.
3. An optical connector according to claim 1 , wherein each of the N×N polymer-dispersed liquid crystal switchable holographic components comprises:
a pair of transparent conductive slides;
a voltage source electrically contacted to the pair of transparent conductive slides;
at least one spacer for separating the pair of transparent conductive slides;
a layer of polymer-dispersed liquid crystal material located within the confines of the pair of transparent productive slides and the at least one spacer; and
a switchable holographic grating formed within the layer of polymer-dispersed liquid crystal material.
4. An optical connector according to claim 3 , wherein the polymer-dispersed liquid crystal material is made from:
(a) a polymerizable monomer comprising at least one acrylate;
(b) at least one type of liquid crystal material;
(c) a chain-extending monomer;
(d) a coinitiator; and
(e) a photoinitiator.
5. The optical connector according to claim 4 , wherein the polymerizable monomer comprises at least one of a di-, tri-, tetra-, and pentaacrylate.
6. The optical connector according to claim 5 , wherein the polymerizable monomer is at least one acrylate selected from the group consisting of triethyleneglycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetracrylate, and dipentaerythritol pentaacrylate.
7. The optical connector according to claim 6 , wherein the polymerizable monomer comprises a mixture of tri- and pentaacrylates.
8. The optical connector according to claim 7 , wherein the polymerizable monomer comprises dipentaerythritol pentaacrylate.
9. The optical connector according to claim 4 , wherein the polymer-dispersed liquid crystal material further comprises a surfactant.
10. The optical connector according to claim 9 , wherein the surfactant is octanoic acid.
11. The optical connector according to claim 4 , wherein the polymerizable monomer comprises dipentaerythritol pentaacrylate, the at least one liquid crystal comprises at least one cyanobiphenyl, the chain-extending monomer is N-vinyl pyrrolidone, the coinitiator is N-phenylglycine, and the photoinitiator is rose bengal.
12. The optical connector according to claim 1 , further comprising:
a third matrix comprised of N×N polymer-dispersed liquid crystal switchable holographic components capable of accepting deflected and transmitted radiation from the second matrix and capable of further deflecting and transmitting the accepted radiation; and
a fourth matrix comprised of N×N polymer-dispersed liquid crystal switchable holographic component capable of accepting from the third matrix the further deflected and transmitted radiation.