Electrically Controllable Liquid Cyrstal Microstructures

 KSU.193

Abstract: Previously proposed methods for building electrically controllable gratings and lenses have used techniques including: (1) one-dimensional grating fabrication using polymer dispersion method, which confines liquid crystals inside microdroplets, but because of the polydispersity of droplet size, their efficiency and optical transmission are limited; (2) liquid crystal confined between polymer walls for some electro-optical devices, using UV exposure and optical masks; and (3) small lenses built using mechanical shaping of substrates.  In all of these cases, it has been difficult to form uniform and small liquid crystal regions at predetermined positions.  This invention provides a simple and low cost method of preparing linear and two-dimensional liquid crystal (LC) gratings as well as microlenses.  The operation of gratings and lenses can be controlled with the application of an electric field.  The structures prepared with this invention are free of microdroplets, which undermine the efficiencies and performance due to light scattering from droplet boundaries.  Preparation method relies on UN exposure of a cell filled with LC + prepolymer mixture and UV exposure using an optical mask, which determines their size and position while appropriately controlling the polymerization rate.  These structures are formed in essentially one step beyond the step of filling the cell.

Applications:

•          Opto-electric devices such as active-fiber star coupler for high-density optical communications
•          Parallel interconnects for neural networks
•          Optical limiters, high-density information storage
•          Optical projection systems, flexible displays, and wider viewing angle LC displays
•          Beam steering devices
•          Variable focal lens arrays, wave-front shaping, etc.

Advantages:

•          One-step processing to form microstructures down to submicron sizes
•          High efficiency, high transmission
•          Easily implementable on existing manufacturing lines

Inventors: Dr. Satyendra Kumar et al