Abstract
Experiments demonstrating extremely rapid modulation of the permittivity have been performed by exploiting the enhanced non-linear effects possible in the presence of plasmonic resonances. These experiments measure an extreme rise time by exploiting the analogy between Young's slits which produce diffraction in momentum space, and closely spaced time windows which produce diffraction in frequency space.
I go on to discuss some theoretical consequences of space-time modulated structures. Diffraction gratings moving at trans-luminal velocities contain points where wave and grating velocity are equal. We show these points can be understood as a series of optical event horizons where wave energy can be trapped and amplified, leading to radiation from the quantum vacuum state. We calculate the spectrum of this emitted radiation, finding a quasi-thermal spectrum with features that depend on the grating profile, and an effective temperature that scales exponentially with the length of the grating, emitting a measurable flux even for very small grating contrast. Stimulated emission also takes place under the influence of incident photons, but in contrast to emission from excited atoms, transluminal systems radiate correlated photon pairs.
Biography
Professor Sir John Pendry received his Ph.D. in Solid State Theory from the University of Cambridge in 1969. He began his career in the Cavendish Laboratory, Cambridge, and later worked at Downing College, Bell Laboratories and Daresbury Laboratory. Since 1981, he has been the Chair in Theoretical Solid-State Physics in the Imperial College London. Professor Sir Pendry is a condensed matter theorist known for his research into refractive indexes and creation of the first practical “Invisibility Cloak”. He has worked extensively on electronic and structural properties of surfaces, developing the theory of low energy diffraction and electronic surface states and transport in disordered systems. He was elected a Fellow of the Royal Society in 1984, and Fellow or Foreign Member in several professional organizations including the American Academy of Arts and Sciences, US National Academy of Sciences, the Norwegian Academy of Science and Letters and the American Physical Society. He has received numerous honors and awards recognizing his contributions, culminating in his knighthood for services to science in 2004, and the Royal Medal of the Royal Society in 2006. He was also awarded the Isaac Newton Medal in 2013, the Kavli Prize in 2014, the Dan David Prize and Ugo Fano Gold Medal in 2016, the John Howard Dellinger Medal in 2017 and the SPIE Mozi Award in 2019.
This event is organized by the Department of Mechanical Engineering and the Department of Physics