Atypical Photonic Solids as Band Gap and Negative Refraction Media

Friday, October 18, 2013

1:30pm | 125 Hudson Hall

Presenter

Chekesha Liddell Watson , Associate Professor, Materials Science and Engineering

New avenues towards artificially generated optical functionality rely on the ability to control light-matter interactions through structuring photonic materials at the mesoscale.  Particularly, the photonic band structures of thin dielectric slabs have been engineered to create [1] overlap between band gap frequencies in both linear polarizations where light transmission is not allowed in the plane of the slab and [2] frequency regions where the effective index of refraction becomes negative.  The manipulations hold promise for advances in signal processing and imaging beyond the diffraction limit, among others. This talk will present our research in combining particle ‘shape programming’ and physical confinement to stabilize and access quasi-2D transition structures that are interrogated for optical band gap and anomalous refraction properties.  Experimentally, the controlled height of confinement in a wedge region enables the study of the diverse self-assembled phases that optimize the packing efficiency of nonspherical particles between two- and three dimensions.  The work addresses the overarching issues How does the interplay between building block shape and lattice symmetry determine band gap formation and negative refraction in photonic slabs?  What degrees of well-defined partial order can promote the desired optical properties?  The optical band gap simulation of centered rectangular arrangements of dimers, dimer cylinders and square bilayers of three-fourths cut-spheres will be presented.  In addition, the refraction behavior of asymmetric dimer-based slabs interpreted from the equifrequency contours will be discussed.  The structures correspond to those found in our experimental systems under confinement conditions as well as through evaporation-mediated assembly.

Chekesha M. Liddell Watson
received a Bachelor of Science in Chemistry with Highest Distinction from Spelman College (1999) and a Bachelor of Materials Engineering from Georgia Institute of Technology (1999).  She was awarded the NASA Women in Science and Engineering Scholarship to support her undergraduate work and held three internship appointments at NASA, Kennedy Space Center in the Cryogenics and External Tank Branch and the Microchemical Analysis Laboratories.  She joined the Cornell University faculty in November of 2003, after receiving a Ph.D. in Materials Science and Engineering with a minor in Science and Technology Policy from Georgia Tech.  Her awards for scholarly achievement include the Provost’s Award for Distinguished Scholarship, Cornell University (2010);  National Science Foundation (NSF) Presidential Early Career Award (PECASE, 2007);  NSF Career Award (2006);  Facilitating Academic Careers in Engineering and Sciences Career Initiation Grant, (2003); Office of Naval Research Graduate Fellowship (1999-2003);  Georgia Tech President's Fellowship, (1999-2003);  Facilitating Academic Careers in Engineering and Sciences Fellowship (1999-2003);  NSBE, National Society of Black Engineers Fellow, (2000);  Hertz Foundation Fellowship Grant, (1999);  TMS materials society, J. Keith Brimacombe Presidential Scholarship, (1999);  ASM Foundation Scholarship, ASM International materials society, (1998);  and the ASTM, American Society for Testing and Materials, Mary R. Norton Memorial Fellowship, (1999).