Mesoscopic Optical Elements
Mesoscopic light emitters, switches, and transformers
Tech Area / Field
- PHY-OPL/Optics and Lasers/Physics
8 Project completed
Senior Project Manager
Safronova O N
National Academy of Sciences of the Republic of Belarus / Institute of Molecular and Atomic Physics, Belarus, Minsk
- Belarussian State University of Informatics and Radioelectronics, Belarus, Minsk
- Universität Dortmund / Institut für Physik, Germany, Dortmund\nEVOTEC BioSystems AG, Germany, Hamburg\nCentro Ricerche FIAT, Italy, Torino
Project summaryDuring the last decades, extensive investigations of optical processes in various artificial inhomogeneous media having spatial structure features on the scale of the order of the de Broglie wavelength of electrons in crystals (1–10 nm) or the wavelength of the optical range photon (100–1000 nm) are carried out. When dimensions of active regions and microinclusions approach the de Broglie wavelength of the electron, a series of quantum size effects appear, among which most important optical effects are size dependencies of absorption and emission spectra and optical transition probabilities. These effects are due to the controlled density of electronic states in semiconductor nanostructures. They open new ways of light-emitting and optical switching devices fabrication. When dimensions of active regions or the period of the dielectric heterostructure approaches the photon wavelength, the density of photon states is changed. This permits, firstly, to control the propagation of light without dissipation (absorption) of the energy, and, secondly, to control the probability of the spontaneous emission of light by excited atoms, molecules, nanocrystals, and other quantum systems. The control of the spontaneous emission becomes possible as a result of the fact that the probability of the spontaneous emission of photons is proportional to the photon density of states. The concept of the photonic crystal, i.e. a periodic medium with a controlled photon density of states, opens up the possibility of development of basically novel light sources: spontaneous emission sources with the controlled emission spectrum, lifetime and directionality.
The phenomena described are related to the class of mesoscopic effects, since they take place in structures taking an intermediate position between micro-(atoms and molecules) and macro-objects (continuous homogeneous media). In addition to the above-mentioned effects, there exist other mesoscopic optical phenomena, namely giant Raman scattering and luminescence enhancement of molecules and atoms at rough metal surfaces and aggregations of metal nanoparticles. The latter provides an ingenious route to novel efficient light emitters, transformers and display materials and devices.
The objective of the project is the use of mesoscopic optical phenomena for the development of novel efficient light emitters, switches, and transformers.
In more detail, mesoscopic effects will be purposefully used to develop experimental grade samples of:
– visible light emitting plates with enhanced efficiency by means of controlled directionality via photonic band gap formation;
– spectral transformers for solar cells and photodetectors based on luminescence enhancement in the presence of metal colloids and spectrum control via electron confinement effects;
– fluorescent aqueous solutions for the visible based on soluble semiconductor nanocrystals;
– wide-band optical switches based on strong nonlinearities due to electron confinement in semiconductor-doped glasses and photon confinement at the interface of two different media;
– thin film amplifiers for optical communication based on Er-doped sol-gel materials containing metal nanoparticles and buffer elements.
Current project-related activities. The solution of the problems formulated will become possible due to the scientific background and the results already obtained by the authors and basic research carried out in related area:
– investigation of light propagation and spectral selection in ultradispersed spatially ordered structures and development of the relevant calculation technique based on multiple wave scattering approach;
– systematic investigation of optical properties of semiconductor nanocrystals;
– investigation of luminescence of rare-earth ions in various matrices including sol-gel films, porous silicon, porous alumina and colloidal silica;
– investigation of light propagation and emission in prototype photonic band gap structures;
– synthesis of mesoporous alumina films with periodic pores and its structural and optical characterization;
– investigation of nonlinear optical processes in nanostructures (S.V.Gaponenko, et al.[Error! Bookmark not defined.]).
The research team includes experts in theoretical optics, physics of nanostructures, luminescence, laser physics, solid state chemistry and glass technology, vacuum film deposition.
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