Beam steering using a new class of fast, high-polarization ferroelectric liquid crystals

It has long been known that optical phased array (OPA) beam steering can be performed by liquid crystal devices, yet available liquid crystals are either too slow for many applications (1 ms - 100's of milliseconds) or they are incapable of producing thenecessary range of analog phase modulation. Developments in a new class of ferroelectric liquid crystals (FLCs) during the last couple of years have the potential to overcome these limitations, enabling OPA beam steering devices with speeds in excess of 5kHz. OPAs consist of two-dimensional arrays of individual FLC phase modulators, they can be made by placing a layer of liquid crystal on the top surface of a specially designed VLSI circuit. The VLSI surface is divided into an array of individualelectrodes, one per modulator. However, optimal drive voltages for the new FLC far exceed the capabilities of normal CMOS VLSI circuitry. We have devised a charge-controlled drive scheme to overcome this problem, allowing the new FLCs to be driven byCMOS-compatible voltages. Using the new FLCs and drive scheme, we propose to develop OPA fine steering mirrors capable of the speed and accuracy required for free space optical communications systems. Successful development of the proposed technologywill benefit commercial users by enabling higher bandwidth free-space communications between points lacking optical fiber links, by improving the quality of information that can be obtained from LADAR systems, and by making available a novel programmableoptics component technology that should be of use in diverse applications such as optical disk drives, holographic data storage, and optical switching. If it can be made cheaply enough, it could also offer a flexible alternative to scanners currently usedfor warehouse inventory control and supermarket scanners which use conventional opto-mechanical mechanisms.