ECE Seminar Series: Bending, trapping and slowing down light beams to enable ultra-fast photodetection and efficient energy conversion

Speaker Name: 
M. Saif Islam
Speaker Title: 
Speaker Organization: 
UC Davis
Start Time: 
Monday, November 25, 2019 - 10:40am
End Time: 
Monday, November 25, 2019 - 11:40am


Photon-material interaction is generally very weak in most semiconductors when incident photon wavelengths are close to their optical band gap. This leads to very weak absorption coefficients requiring considerably thick semiconductor films for efficient light absorption. However, a photodetector designed with thick absorption region cannot operate at high-speed due to long carrier drift-time. In addition, most emerging 2D materials with their diminishing thickness and ultra-short interaction time with photons are generally deemed to be impractical for optoelectronic applications because of very low absorption efficiency, despite their ultra-fast response time. In this presentation, we will demonstrate a technique to bend normally incident beams of light by almost ninety degrees into laterally propagating modes of light along the plane of semiconductor films by using a periodic array of micro and nanoscale holes. Such structures bend light beams, slow them down and contribute to unprecedented improvement in the light absorption efficiency in devices, even when they are designed with very thin absorption regions. This opens new application opportunities such as ultra-fast CMOS compatible photodiodes for datacenter communication links, LIDER, advanced bio imaging and sensors and highly efficient solar cells.


M. Saif Islam received his B.S. Degree in Physics from Middle East Technical University (1994, Turkey), M.S. degree in Physics from Bilkent Univ (1996, Turkey) and Ph.D. degree in Electrical Engineering from UCLA in 2001.  He worked for JDS Uniphase Corp, Gazillion Bits, Inc. and Hewlett Packard Labs before joining UC Davis in 2004, where he is a Professor and the Chair of the ECE Department. He has authored/co-authored more than 250 scientific papers, organized 32 conferences/symposiums as a co-chair; and holds 41 patents as an inventor/co-inventor. He received NSF Faculty Early Career Award, Outstanding Junior and Outstanding Mid-Career Research Faculty Award, IEEE Professor of the Year and UC Davis Academic Senate Distinguished Teaching Award. He is an elected fellow of the American Association for the Advancement of Science (AAAS), Optical Society of America (OSA), International Society for Optics and Photonics (SPIE) and the National Academy of Inventors (NAI).
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