Liquid Crystals for Ultrafast (sub-picoseconds, femtoseconds) Photonics

Abstract:

Soft, chiral photonic crystals such as cholesteric liquid crystals [CLC] possess unique advantageous properties such as highly tunable band gaps, large band-edge dispersion and ultrafast optical nonlinearities. While most conventional applications require only microns thick interaction length, some advanced photonic applications such as switching of complex laser vector beams, optical field-induced modulation and ultrafast (femtoseconds) pulse compression demand unconventional > mm thicknesses.

This presentation will review some underlying liquid crystals fundamentals, and recent advances, and our latest work in fields-assisted/directed assembly techniques that enables robust fabrication of stable well-aligned cholesteric liquid crystals to unprecedented thickness up to 2.2 mm impossible with any existing technique on soft matter synthesis. These super-thick CLC exhibit many capabilities impossible with other chiral photonic crystals - broad spectral window with near-unity transmission, large optical rotation power and ultrafast nonlinearity and dynamic tunability for free-space application with ultrafast-CW lasers throughout the entire visible to mid- infrared regimes.

Bio:

Iam Choon Khoo received the Ph. D. in Physics (Quantum Optics) from the University of Rochester. He joined the faculty of Electrical Engineering at PSU in 1984 and currently holds the William E. Leonhard Professorship. He authored/co-authored 294 journal publications, and two widely cited (~3100 times) books on optical physics, optics and nonlinear optics of liquid crystals and made over 430 technical presentations (266 Plenary/Keynote/Invited).

Exemplary honors and awards include the 1988 Faculty Scholar Medal for Outstanding Achievement in Physical Science and Engineering at PSU, 2003 Sturgeon Memorial Plenary Lecturer, Cambridge University, and the 2024 SPIE Maria Goeppert-Mayer Award in Photonics. He is a Fellow of: IEEE (Life), Optica (formerly OSA) and the UK Institute of Physics.