Contact Information for Ravi Komanduri
Liquid Crystal Displays, Spatial Light Modulators, Diffraction, Polarization Gratings, Holographic Lithography, Organic Electronics, Polarization Transformation Elements, Diffractive Switches and Photonic Crystals based devices.
My research so far has involved exploring the interesting electro-optical properties of the Liquid Crystal Polarization Grating. Polarization Gratings (PGs) constitute a new class of optical elements that periodically modulate the polarization state of light. Their unique optical properties have been utilized recently in several applications including polarization independent displays, wide-angle non-mechanical beam-steerers, tunable optical filters, light shutters, polarimeters etc. High quality PGs have been demonstrated in commercially available monomer and polymer LC materials that achieve excellent optical properties both for narrowband and broadband wavelength operation on both transmissive and reflective substrates.
POLARIZATION INDEPENDENT MODULATION: Most conventional Liquid Crystal Displays (LCDs) use polarizers to create polarized light essential for display operation. This results in more than 50% loss in optical efficiency because in many cases the unwanted light is either not recovered or absorbed. Unlike these conventional approaches, we were able to use the unique polarization sensitive properties of broadband polymer PGs in combination with conventional LC modes to modulate unpolarized light without encountering such losses. The polymer PGs selectively direct the diffracted orders whose polarization states are modulated by the active LC switch. This technique combines the diffractive properties of PGs, and polarization manipulation capabilities of ordinary LC modes to modulate both orthogonal polarizations simultaneously thus achieving high throughput unlike prior LC switches. We recently reported on a truly polarization-independent diffractive light shutter that proves this concept, and has tremendous implications for various applications including displays, light switches, etc.
ENERGY EFFICIENT PICO-PROJECTORS: Conventional LCD schemes are not practical when we talk about a new generation of portable projectors where battery life is limited because of their limited optical efficiency. Utilizing the polarization independent modulation capabilities of PGs discussed above, in collaboration with ImagineOptix, three generations of energy-efficient portable projectors have been created that not only address this issue but are also compact, cheap to manufacture in a large volume, etc. There is ongoing research as this technology is commercialized to improve other aspects of such projectors such as contrast-ratios, color uniformity, etc.
In addition to the above projects, I am currently investigating new holographic/lithographic approaches for patterning PGs suitable for large volume manufacturing. We are also exploring novel polarization transformation elements based on Liquid Crystal Polymers which are easy to manufacture and rival the performance of their commercial counterparts.