Speaker: W. Kiefer(Institute for Physical and Theoretical Chemistry, University of Würzburg, Germany and Eisingen Laboratory for Applied Raman Spectroscopy (ELARS), Eisingen, Germany)

 

Time: Nov. 1, 2019 2：00 PM 

 

Venue: No. 303 meeting room of building 2, IOS, CAS  

 

Abstract：Vertical cavity surface emitting lasers (VCSELs) have long been predicted as low-cost enabling laser sources for many applications including optical communications, sensing and imaging. The VCSELs comprise a quantum well active region sandwiched between two highly reflective mirrors, all epitaxially grown on a GaAs or InP substrate. With the laser emitting in the surface normal direction, VCSELs enjoy the advantages offered by LEDs in wafer scale processing and easy of packaging.  The mirrors are typically distributed Bragg reflectors (DBRs) with many tens layers of epitaxy layers with alternating refractive indecies. Since 2004, we invented a single layer high index contrast near-wavelength gratings (HCG) to replace the hundred-layered DBR in a VCSEL structure.  Snice then, we develeoped a new class of planar optics has emerged using near-wavelength dielectric structures, known as high contrast metastructures (HCM).  Many extraordinary properties can be designed top-down based for integrated optics on a silicon or GaAs substrate. In this talk, I will review recent results using HCG as mirror for VCSEL as well as biosensor, 4-wave generation, and spatial light modulator.  I will discuss inventions and advances in VCSELs that have led to recent global deployment of commercial applications including 3D sensing, LIDAR and optical coherent tomography applications.  I will also discuss future prospects for advanced applications.

 

Biography:Wolfgang Kiefer had been Associated Professor of Experimental Physics at the University of Bayreuth, Germany, from 1977-1985 and Full Professor for Experimental Physics at the University of Graz, Austria from 1985-1988. He then accepted a chair in Physical Chemistry at University of Würzburg where he stayed until his retirement in 2006. He has been and still is member of several scientific journals, and he had been Editor-in-Chief of the Journal of Raman Spectroscopy from 2000 to 2009. His research interests are mainly concerned with several aspects of Raman spectroscopy ranging from the development of new techniques, resonance Raman and surface enhanced Raman spectroscopy, Raman/Mie scattering, to non-linear Raman spectroscopies with femtosecond lasers. He has published about 900 papers.  He is Honorary Professor and Honorary Doctor of several international Universities. He also received many awards, among them the prestigious Pittsburgh Spectroscopy Award and the first Raman Lifetime Award provided by the International Conferences on Raman Spectroscopy. He is member and Honorary Member of several Scientific Societies. After his retirement in 2006, he has set-up a Raman laboratory in the basement of his home.