Photonic Band Gap Materials: Light Control at Will




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Tight-binding in a new light: Photons in periodic and disordered lattices



Yaron Silberberg

Depart.Phys. Complex Sys., The Weizmann Inst. Science, Rehovot, Israel


Abstract


The 1-dimensional tight binding approximation has been extremely useful to explain the basic properties of condense matter, from ballistic transport and energy bands to Anderson localization and many body effects. The photonic version of this system, based on arrays of coupled waveguide, enables direct and simple observation of asic properties of this system, including the evolution of eigenfunctions and even studies of interactions. This talk reviews several of our recent studies of light propagation in disordered lattices and of quantum correlations in these systems.


Light localization for structuring of materials and sensing



Saulius Juodkazis

Centre for Micro-Photonics, Swinburne University of Technology, Hawthorn,

VIC 3122, Australia

SJuodkazis@swin.edu.au


Abstract


Achieving a molecular/atomic resolution in three-dimensional (3D) structuring of materials is now motivating research in number of different directions of science and technology. The single-molecular resolution demonstrated by optical fluorescence microscopy is becoming a standard tool advancing research of photo-active bio-materials. Microscopy can localize an incoming light into a spot comparable with the wavelength. When ultra-short, sub-1 ps laser pulses are used, the localization of modification can be further increased via nonlinearity of light-matter interaction. This is a current trend in search for methods allowing to break into actual nano-realm of laser structuring where the feature size should be controlled with sub-100 nm resolution in all three dimensions. As a first step towards this goal, the precision of light energy delivery and localization should be controlled with the adequate accuracy. This implies that tightly-focused laser pulses with power below the threshold of self-focusing are required for the 3D nano-structuring.

We overview some recent results on 3D laser structuring of photo-polymers, glasses, and crystals by femtosecond (fs) laser pulses. The regions modified by laser pulses with high energy concentration, achieved by the ultrashort tightly-focused pulses, can be defined with resolution of tens-of-nanometers. The local field enhancement effects in laser structuring of materials are discussed.

By using plasmonic nanostructures light localization can be further enhanced and reaches cross sections of 10 nm or even less. By exploring properties of photo-absorption and thermal localization by nano-structures, photo-modification can be controlled on a nanoscale. This approach is becoming main stream in sensing and light harvesting applications. Nanoparticle-patterned electrodes are performing photo-catalytic, water splitting, and light-to-electricity conversion tasks. Some results in light localization and light-field enhancement by plasmonic nano-particles will be presented and discussed.

Dynamics of localized waves in quasi-one-dimensional open media



Z.Q. Zhang,1 A.A. Chabanov,2 S.K. Cheung,1 C.H. Wong,1, and A.Z. Genack3

1Department of Physic, Hong Kong University of Science and Technology

2Department of Physics and Astronomy, University of Texas at San Antonio

3Department of Physics, Queens College, City University of New York


Abstract


We have studied the dynamics of localized waves in quasi-one-dimensional open media. Four theoretical approaches were used to explain the measured pulsed microwave transmission: (i) diffusion theory; (ii) self-consistent localization theory (SCLT) with a position- and frequency- dependent diffusion coefficient; (iii) a dynamic single-parameter-scaling (DSPS) model, which reflects the decay of isolated localized modes; and (iv) simulations of 1D random medium. It is found that the measured decay rate can be well described by the SCLT up to four times the diffusion time. For longer times, the SCLT fails to capture the long-lived localized modes and gives a faster decay rate. Beyond the Heisenberg time, the measured data approaches the prediction of the DSPS model, reflecting the increasing proportion of wave energy in long-lived localized modes. However, the DSPS model fails at short times due to the absence of necklace states in the model. At long times, the decay rate obtained from 1D simulations are also in good agreement with the measured data and coincide with the decay rate given by the DSPS model.


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