纳米光子学：概述 81p.pptVIP

纳米光子学：概述 NSF-RISE Workshop July 9-14, 2007 Anup Sharma Department of Physics Alabama AM University What is Nanophotonics?Science of Light-Matter Interaction at Nanometer scale ( 1 micron to ≥ 1 nm) Examples of Nanophotonics Iridescent colors on butterfly wings are due to Photonic-Crystals. i.e. Stacks of Nanoscale Gratings Emission of Semiconductor (CdS, InAs, InP, CdSe) Nanospheres depends on the size Metal Nanoparticles Enhance Raman Scattering Signals by several orders of magnitude Nanophotonics can be divided into three parts 1. Nanoscale confinement of Radiation 2. Nanoscale confinement of Matter Nanoscale Cyrstals are used for: (i) Optical Upconversion of radiation in Rare-Earth Nanocrystals. (ii) Size-dependent Emission properties of nanoscale semiconductor crystals (Quantum dots or Q-dots) Metal nanoparticles and nanotips used in Surface Enhanced Raman Spectroscopy Photonic Bandgap Crystals and Photonic Bandgap Fibers (Photonic Fibers) involve periodic variation of dielectric constant over wavelength-scale. Applications: Fabrication of MOEMS (Micro Opto Electro Mechanical Systems), Micro-Optics, i.e. Microlasers, Directional Couplers between waveguides, Biophotonic Chips etc. 3. Nanoscale Photoprocesses Examples: Nanoscale Lithography, Fabrication of Nanoscale Structures, Nanoscale Optical Memories Maxwell’s Equations for Light Free Space Solutions: Propagation through Classically Forbidden Zones: Photon tunneling through classically forbidden zones. E and B fields decay exponentially. k-vector imaginary. Confinement of Light and Electrons Confinement of Light results in field variations similar to the confinement of Electron in a Potential Well. For Light, the analogue of a Potential Well is a region of high refractive-index bounded by a region of lower refractive-index. Differences between Light and Electron Waves: Electron Momentum generally bigger than photon momentum and so wavelength of light generally 1 micron while wavelength of elect