Our research program revolves around two themes: (1)"The Collective Dynamics of Disordered Solids". Collective Dynamics are characterized by a correlation length and a correlation time. More generally, correlation on different length scales can be characterized by different characteristic times. When the length over which the solid is disordered equals the primary correlation length, the cooperative character of the dynamics should be significantly perturbed if not destroyed. (2)" Nonlinear Optical Phenomena in Glasses and Fibers". These phenomena constitute the basis of next generation all optical telecommunications' networks. We are particularly interested in identifying the microscopic origin of these nonlinearities and in developing new ways to control them.
Research Areas of Interest:
Optical non-linearities in glasses, optical fibers and photonic crystals (stimulated Brillouin and Raman)
Structural phase transitions in compositionally disordered systems
Lattice dynamics in disordered ferroelectrics (soft modes and central peaks)
Non-linear properties of disordered ferroelectrics
Low frequency vibrational dynamics and slow relaxation in glasses (relationship between structural and dynamical features on different length and time or frequency scales, e.g. Boson peak)
Liquid-Glass transition in strong and fragile glasses
Non-linear Optics in glasses and optical fibers (e.g. stimulated Raman and Brillouin)
Propagation of light in photonic crystals
Experimental and theoretical studies of structural and ferroelectric phases transitions in disordered and partially ordered crystals (phonon dynamics and localized vibrations in relaxor ferroelectrics)
Experimental Techniques Used:
Raman and Brillouin Scattering
Neutron Scattering
Ultrasonics, Dielectric and Polarization Spectroscopies
X-ray Diffraction
Pulsed NMR
Cryogenics
Fiber optics-Stimulated Raman and Brillouin Scattering- Four Wave Mixing
Recent Grants and Active Contracts:
National Science Foundation, 8/1997-8/2000, "Collective Dynamics of Disordered Solids".
National Science Foundation, 1999-2004. "GOALI: Optical Nonlinearities in Glass Fibers and Their Effects on the Guided Propagation of Light". This represents a collaboration between J. Toulouse, D. Christodoulides in EECS and H.Jain in MSE at Lehigh and two research scientists at Lucent Technologies/Bell Laboratories in Murray Hill (NJ).
National Science Foundation, 2001-2003, instrumentation grant to for fiber optics research.
National Science Foundation, 2000-2001, in collaboration with Mark Bickhard, "Complex Systems from Physics to Biology".
Department of Energy, 2000-2004, "Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectrics and the Search for New Relaxor Materials for Transducer and Optical Applications".
Center for Optical Technologies, 2003-2006, for support of the All-Optical Functionalities Thrust Team (10-12 faculty/graduate students/postdocs participants, not own individual grant).
US Department of Energy, 2006-2009, "Multiscale Dynamics of Relaxor Ferroelectrics".
National Science Foundation, 2004-2007, "Optical Nonlinearities in Microstructured Fibers for All Optical Network Functionalities".
National Science Foundation, 2004-2006, "Microstructure Tellurite Fibers Produced by Extrusion for Nonlinear Applications".
Office of Naval Research, 2005-2008, "Development of Active Infrared Sensing and Teraherts Imaging Systems for Countering Improvised Explosive Devices.
