The Nanophotonics research group at Georgia Tech is led by Prof. Chris Summers in the School of Materials Science & Engineering.
The groups research goals center on developing and characterizing new 2D and 3D photonic crystal (PC) materials and phosphors. Active areas of research include modeling and simulation of 2D and 3D photonic crystal structures using both the Plane Wave Expansion (PWE) and Finite-Difference Time-Domain (FDTD) methods. Experimentally, we have several members focused on fabricating inverse opal structures. Our primary method of opal infiltration is Atomic Layer Deposition (ALD), and we have built ALD reactors for oxide (TiO2, Al2O3, ...) and phosphide (GaP, InP, ...) thin film growth. We also have several students working on luminescent quantum dots and phosphors for incorporation into photonic crystal structures. More information about our research areas can be found by following the links below.
2D Photonic Crystals:
Our effort is directed to the design and fabrication of novel two-dimensional photonic crystals for controlling light. Currently we are pursuing new concepts to obtain very large and tunable refraction and dispersion properties, and to reduce beam divergence and to focus propagating beams.
3D Photonic Crystals:
Our primary thrust is to investigate and to develop novel wide photonic band gap three-dimensional PC architectures for generating and controlling light. A major focus of our effort is designing and fabricating inverse opal-based structures using atomic layer deposition and selective etching. Luminescent properties have been obtained by incorporating phosphor or QD materials into the structures and dynamical tuning by the infiltration of nematic liquid crystals. Recently, holographically defined polymer templates have been infiltrated and inverted by these techniques.
Conventional & Quantum Dot Phosphors:
New luminescent materials are being developed for displays, solid state lighting and X-ray imaging applications. Currently, non Cd-based technologies for solid state lighting are being developed based on III-V quantum dot (QD) materials that enable the whole visible spectral range to be covered. Also, coating techniques are being developed to control both QD size and surface recombination properties. Future work will be directed to the formation of core/shell structures and the synthesis of doped nano-particles. The investigation of X-ray phosphors is directed to the development of high efficiency ZnTe:O doped materials prepared by a dry synthesis method.
Nanotechnology & Spintronics:
In cooperation with Professor Wang's and Professor Ferguson's programs, the properties of ZnO nanowires, nanorods and nanobelts are being investigated and work is being performed on the development of spintronic materials and devices.
Atomic Layer Deposition:
New protocols for atomic layer deposition have been developed, primarily in support of the 3D photonic crystal program, which involves the infiltration of highly porous opal and holographically formed templates. Materials investigated include, TiO2, Al2O3, ZnO, ZnS:Mn and GaP and InP. Recent efforts include hermetically coating phosphors and related display material structures.
"Enhanced tunable Bragg diffraction in large-pore inverse opals using dual-frequency liquid crystal,"
E. Graugnard, S. N. Dunham, J. S. King, D. Lorang, S. Jain, and C. J. Summers, Appl. Phys. Lett. (in press).
"Tunable Bragg peak response in liquid crystal infiltrated photonic crystals,"
D.P. Gaillot and C.J. Summers, J. Opt. Soc. Amer. B 24, 7 (2007)
"Photonic band gaps in non-close-packed inverse opals,"
D. P. Gaillot and C. J. Summers, J. Appl. Phys. 100, 113118 (2006).
"Photonic band tuning in two-dimensional photonic crystal slab waveguides by atomic layer deposition,"
E. Graugnard, D. P. Gaillot, S. N. Dunham, C. W. Neff, T. Yamashita, and C. J. Summers, Appl. Phys. Lett. 89,181108 (2006).
Selected for the Virtual Journal of Nanoscale Science & Technology, 14 November 13 (2006).
"Luminescent and tunable 3D photonic crystal structures,"
C.J. Summers, E. Graugnard, D. P. Gaillot, and J.S. King, J. Nonlinear Opt. Phys. Mater., 15, 203 (2006).
"Polarization beam splitter based on a photonic crystal heterostructure,"
E. Schonbrun, Q. Wu, W. Park, T. Yamashita, and C. J. Summers, Optics Letters 31 (21), 3104-6 (2006).
"Negative index imaging by index-matched photonic crystal slab,"
E. Schonbrun, T. Yamashita, W. Park and C. J. Summers, Phys. Rev. B 73, 195117, (2006).
"Liquid-Crystals for optical filters, switches and tunable negative index material development,"
I.C. Khoo, Y. Williams, A. Diaz, K. Chen, J. A. Bossard, L. Li, D. H. Werner, E. Graugnard, J. S. King, S. Jain, and C. J. Summers, Molecular Crystals and Liquid crystals, 453, 309 (2006).
"Infiltration and inversion of holographically-defined polymer photonic crystal templates by atomic layer deposition,"
J. S. King, E. Graugnard, O. M. Roche, D. N. Sharp, J. Scrimgeour, R. G. Denning, A. J. Turberfield, and C. J. Summers, Adv. Mater. 18, 1561 (2006).
"Sacrificial-layer atomic layer deposition for fabrication of non-close-packed inverse opal photonic crystals,"
E. Graugnard, J. S. King, D. P. Gaillot and C. J. Summers, Adv. Func. Mater. 16, 1187 (2006).
"Conformally back-filled, non-close-packed inverse-opal photonic crystals,"
J. S. King, D. Gaillot, E. Graugnard, and C. J. Summers, Adv. Mater. 18, 1063 (2006).
"Photoluminescence modification by high-order photonic bands in TiO2/ZnS:Mn multilayer inverse opals,"
J. S. King, E. Graugnard, and C. J. Summers, Appl. Phys. Lett. 88 081109 (2006).
"Effects of annealing atmosphere on the luminescent efficiency of ZnTe:O phosphors,"
Z. T. Kang, H. Menkara, B. K. Wagner, C. J. Summers, R. Durst, Y. Diawara, G. Mednikova, T. Thorson, J. Lumin. 117, 156-162 (2006).