Optical pulse propagation and direct observation of superluminality in different dispersive media

Venue: Room 201, No. 12 Teaching Building, Yuquan Campus 

Abstract:

The propagation of optical pulses has been investigated in different dispersive media. A transition from the Superluminal to subluminal of the propagation velocity is observed through a resonantly absorbing medium when the propagation distance is changed from a short to long range. The propagation velocity is described within the framework of net group and reshaping delays, even the medium causes a great deal of deformation in the transmitted pulse. This has been confirmed for arbitrary shape of pulses through different types of absorptionless dispersive media such as angularly dispersive one, photonic crystal fiber, etc. However, in the case of phase modulated chirping pulses in a resonant absorber, the propagation velocity is strongly influenced by the reshaping delay. Direct observation of superluminality or fast light has been confirmed from a series of experiments of pulse propagation through a fiber ring resonator within its negative group delay limit. It is observed that the superluminal propagation of pulse peak is an analytic continuation over time of the earlier portion of the input pulse envelope.

Speaker:

Aminul Islam Talukder is a Professor of Physics at Dhaka University. He received his Ph.D. from Shizuoka University, Japan in 2001. Prof.  Talukder’s research interests include superluminal light: measurement and it’s generalization in terms of group velocity, laser spectroscopy such as Raman and LIBS, nanoparticle fabrication using laser ablation technique, etc.  He has published about 40 research papers, 1 book chapter and about 20 presentations/talks at international conferences, on topics such as superluminal pulse propagation, Raman spectroscopy, laser induced breakdown spectroscopy, fabrication of metallic nanoparticles using laser ablation technique, etc. He has received Razzaq Shamsun research award (for best research in Bangladesh) from Dhaka University. He was awarded with 3 postdoctoral fellowships; one from Commonwealth Scholarship Commission during 2009-2010 at ORC, University of Southampton, UK and two other from JSPS (Japan Society for the Promotion of Science) during 2003-2005 and 2012-2013 at Shizuoka University, Japan. He was the regular associate of Abdus Salam International Center for Theoretical Physics (ICTP) during 2006-2012.