Boston Chapter of the IEEE Photonics Society

Wed
Oct 19, 2005
7:00 PM
 

MIT Lincoln Laboratory
 

Terahertz Radiation in Ferroelectric Crystals: Spectroscopy, Coherent Control, Polaritonics, and Applications

Dr. David Ward, Harvard University

Abstract:  When terahertz radiation propagates in an ionic crystal the electromagnetic field couples to the phonon modes of the crystal resulting in an admixture of photons and phonons known as phonon-polaritons.  The variation of the index of refraction from the ionic displacements associated with the phonon component of the mixture can be imaged using standard techniques of phase-to-amplitude imaging and facilitates direct observation of the electromagnetic wave as it propagates through the host crystal.  If a ferroelectric crystal is employed, then optical laser light can generate the terahertz radiation through impulsive stimulated Raman scattering or difference frequency mixing.  This is easily implemented with a standard Ti:Saph amplified laser system.  Patterning of the host crystal facilitates an all-optical, single crystal platform providing generation, guidance, signal processing, and detection of terahertz radiation and requires no free space propagation.  Further, optical pulse shaping enables coherent control over the terahertz waveforms generated.  These polaritonic devices fill the gap between electronics and photonics.  Generation, propagation, guidance, control, and detection of terahertz radiation in ferroelectric crystals, as well as applications, will be presented.

Biography:  David W. Ward received his B.S. degree in physics in 1999 from the College of Charleston and his Ph.D. in physical chemistry in 2005 from the Massachusetts Institute of Technology.  Dr. Ward is a co-founder of the field of polaritonics, which is an intermediate frequency regime between electronics and photonics where signals are manifest as admixtures of photons and phonons.  He is presently a postdoctoral fellow at Harvard University.  His interests are in terahertz technology, negative refraction, nanophotonics, single molecule detection, and finite-difference time-domain and molecular dynamics simulations.  Dr. Ward received the Qauttrochi scholarship as an undergraduate and was a finalist for the Truman Fellowship.  He is a member of the American Physical Society, the Optical Society of America, and the Materials Research Society.