Three Dimensional Gap Photonic Crystal: An Engineered Electromagnetic Platform for Manipulating Light-Matter Interaction

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Date/Time:Thursday, 28 Oct 2010 from 3:00 pm to 3:50 pm
Location:18/19 Physics at 3:00-4:00 p.m.
Channel:Condensed Matter Physics
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Ganapathi Subramania
Sandia National Laboratories, Albuquerque, NM 87185

Photonic crystals (PC) are structures consisting of periodic electromagnetic potential that give rise to a
"photonic" band gap and bandstructure with ability to control the creation, flow and absorption of
electromagnetic waves or photons in unprecedented ways. PCs, especially those possessing a full‐three
dimensional gap that can provide ultimate control of light, have been a long sought after goal. Since the
discovery of the "logpile" PC with a full three dimensional gap and its subsequent experimental
demonstration using alumina rods at microwave frequencies by the ISU group, considerable progress
has been made towards extending this phenomena to higher frequencies where many application areas
lie. I will discuss progress and results achieved at Sandia towards realizing logpile photonic crystals that
can possess photonic bandgaps in the infrared, visible and near‐UV spectral range. In order to operate at
such high frequencies the characteristic dimensions such as the lattice constant and the "atom" size
have to be in the 100s of nanometers. This requires specialized fabrication approaches based on
multilevel electron beam lithography. Using this approach we have demonstrated logpile PCs with as
many as nine layers (~2 unit cells in the growth direction) composed of Si and Au operating in the
infrared , TiO2 operating in the visible and near‐UV, and very recently GaN operating in the visible. We
have demonstrated emission control of visible emitting CdSe quantum dots(QDs) introduced into a
visible bandgap TiO2 logpile PC. By careful introduction of the QDs into the lattice that enables
maximum interaction with local photonic density of states (LDOS) we observe emission suppression in
the bandgap and emission enhancement at the bandedge. More recently we have demonstrated that
logpile GaN PCs can be fabricated through MOCVD based epitaxial growth though a silica based 'inverse'
template. Since GaN is an important material for solid state lighting this is a significant step towards
leveraging emission control properties of 3DPCs to enhance the brightness and efficiency of GaN based
light emitting diodes. Finally, I will discuss introduction of nanocavities into these 3DPC systems in order
to achieve further light control such as Purcell enhancement and strong light matter coupling.

Sandia National Laboratories is a multi‐program laboratory managed and operated by Sandia
Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of
Energy's National Nuclear Security Administration under contract DE‐AC04‐94AL85000.