The overall objective of this research program is to develop liquid crystal (LC) polarization gratings (PGs) for novel photonic elements (Fresnel optics, vortex beam tools, and polymer lasers) with exceptional control over the intensity, direction, orbital angular momentum, and polarization of light. These anisotropic diffractive elements are composed of bulk nematic LCs, can be made in switchable or polymer materials, and are highly efficient. The first goal is to develop PG-based Fresnel zone plate optics, with potential for remarkably small f-numbers, unique polarization behavior, and compelling switchable lens devices. The second goal is to investigate efficient and scalable helical (vortex) beam tools, based on forked PGs, with unprecedented ability to generate and measure orbital angular momentum. The third goal is to employ small-period gratings (sub-micron) to investigate distributed feedback effects, using nematic semiconducting polymers to build organic light-emitting-diodes, and using reactive mesogens doped with fluorescent dyes to build surface-emitting polymer lasers.
Intellectual Merit: The PGs with complex 2D profiles proposed represent a new class of efficient and flexible Fresnel optics with potential for extremely small f-numbers, would lead to novel vortex beam tools that could dramatically impact quantum communication and cryptography, laser-tweezers, lithography microscopy, and could lead to optically pumped polymer lasers with lower thresholds and higher efficiencies.
Broader Impact: This program includes graduate/undergraduate course innovation and multidisciplinary training in experiment and theory. In collaboration with AventWest Children's Mentoring program and NCSU Science House, the PI will host after-school and summer sessions for middle/high-school students involving hands-on engineering projects.
