After obtaining his Ph.D. degree, Dr. Das joined the Department of Radio Physics and Electronics, University of Calcutta, as a full-time Lecturer in 1994, where he is currently a Professor. He is presently the Director, Centre for Research in Nanoscience and Nanotechnology (CRNN), University of Calcutta. He served as the Head of the Department, the Dean, Faculty for Post Graduate Studies in Engineering & Technology, and also earlier as the Director, CRNN, University of Calcutta.

As Dean of the Faculty of Engineering & Technology, of special mention, he took a lead role to successfully launch the 4-year B.Tech. course in all Engineering and Technology streams of the University for the first time from 2015. After framing the modalities of the course, he put tremendous effort to arrange new infrastructure for classrooms and laboratories, including resource persons to run the combined first year classes of B.Tech. course in the Technology campus. 

Dr. Das started his research career in the studies on the physical, electronic and optoelectronic properties of submicron structures of semiconductors. His current research interests include semiconductor photonic devices and systems including nanophotonics, with main focus on modeling and design. He spent nearly 3 years in the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Onatrio, Canada as a Post-Doctoral Fellow and later as a Post-Doctoral Research Associate. Later, he visited Trieste, Italy as a Senior Guest Scientist, and the McMaster University, Canada, the University of Sheffield, UK, and Pohang University of Science & Technology (POSTECH), Korea as a Visiting Professor and Collaborator. He visited Chair "Materials Science and Nanotechnology" of Technical University Dresden, Germany during Aug.-Sep. 2018 with INSA-DFG award. He ran collaborative program such as UKIERI with University of Sheffield (UK), and was the key person from University of Calcutta for Erasmus Mundus ‘LEADERS’ program-a consortium of 13 Asian and 7 European Universities/Institutions.

Dr. Das was the Founder/ Chairman of the IEEE Photonics Society (formerly LEOS) Calcutta Chapter (2004). He took initiative on behalf of the IEEE PS Calcutta Chapter to celebrate National Science Day in Science College of he Calcutta University, in which students of various schools (and in some cases, colleges) were invited to attend the day-long program comprising Lectures and Demonstration on various topics on science the participating students learn in schools. Later, it was organized as outreach programme in different schools in remote areas to spread awareness in science as a part of community programme. Besides, Science and Technology Exhibition were organized as model demonstration cum competition among different colleges. The Chapter was awarded with Most Improved Chapter Award 4 times so far for its exemplary activities.  He also took initiative to form the first ever IEEE Calcutta University Student Branch, in 2006, and since then acting as Student Branch Counsellor to motivate students to take part in several scientific and technological activities.