לוח שנה משולב

In this seminar, I will introduce the fundamentals of guided optics. A brief overview will be given over design, fabrication and characterization of integrated optical components and microfluidic channels. I will focus on the conceptual importance of the integrated optics and surface modification for chemo- and bio-applications. The potential of disorder-enhanced photonics in vibrational spectroscopy on waveguides will be discussed and new directions will be proposed. Vibrational spectroscopy relies on absorption of electromagnetic radiation by molecular vibrations. It is a powerful tool for drawing information on molecular structure and dynamics. In the first part of the talk I will present an intriguing physical effect of disorder-enhanced absorption of light by molecular overtones of amines in a: 1) silicate channel waveguide and 2) microtapered fiber with adsorbed gold nanoparticles. Due to the guides’ surface modification, aromatic rings tend to stack together, and N-H bonds in amines form hydrogen bonds with each other. This 8 nm thick multilayer structure of lamellar liquid crystal shape leads to the switch from ballistic to diffusive propagation of light which results in the enhanced absorption. I will also address a dynamics of absorption as a function of time of adsorption of the organic molecules on waveguide. These phenomena are expected to find application in organic solution based optical sensors for detection of explosive materials and diagnostics of psychoactive stimulants based on amines. In the second part of the talk, I will present a theoretical study of composite plasmonic waveguide structures for design of integrated optical components and Purcell enhanced chemiluminescence in a microfluidic channel.

If you require further information, please contact Chaya Moykopf (4048)

High-redshift science has been rapidly advancing in recent years on both theoretical and observational fronts. However, it is still vastly unclear whether galaxies could have reionized the universe, on what timescale, and what are the properties of these galaxies. I will review results from several recent projects we have been involved in, aimed to enhance our understanding of the first galaxies and the reionization process. In the first part of the talk I will review cluster lensing and recent advancements in lensing-related science, and in the second part I will concentrate on high-redshift galaxies. I will show that the crossroad of the two fields has been particularly useful to boost high-redshift science and our view of the reionization epoch. New efforts now underway with HST, Spitzer, and 10m ground-based telescopes will be overviewed, including some exciting results from Keck that potentially challenge our current understanding of reionization. Possible scenarios for reconciling this tension will be reviewed.