Prof. Vijayan’s Work Featured on Cover of Prestigious Journal ‘Advanced Optical Materials’, Published by Wiley, Garnering Global Recognition

Prof. C. Vijayan completed his M.Sc. and Ph.D. (Physics) at the Indian Institute of Technology (IIT), Madras. He started his career as a Physics teacher and researcher at Pondicherry University and later shifted to IIT Madras after five years. He retired as Professor in 2023 after a distinguished career of thirty years at IIT Madras.
Prof. Vijayan has handled core courses in Physics for engineering and science students at UG, PG and PhD levels and electives in the areas of Optics, Lasers, Nanophotonics and Nonlinear Optics.
His research on light-matter interaction in quantum dots, random media and nonlinear optical materials has resulted in over 220 publications in international journals and conference proceedings. Several of his papers have received high citations, best paper awards, and cover page highlights. He has handled projects for DST, CSIR and DRDO and had research collaborations with Universities in Singapore and Germany where he has also served as visiting professor. He is active as a resource person in Faculty Development Programs, DST INSPIRE and Science Outreach. He was invited to inaugurate the Golden Jubilee Lecture Series of the NCERT in 2011. IIT Palakkad has invited him to serve as an Honorary Professor. A book on Nonlinear Optics was co-authored by Professor Vijayan and published by Wiley International in 2014. The second edition of this book was published by Springer in 2021. He also wrote a popular science book in Malayalam language, about Wonders of Light.

Advanced Optical Materials (Wiley), 11(15) August 2023

Emergence and Relaxation of an e–h Quantum Liquid Phase in Photoexcited MoS 2  Nanoparticles at Room Temperature

Pritha Dey, Tejendra Dixit, Vikash Mishra, Anubhab Sahoo,  Cheriyanath Vijayan ,  Sivarama Krishnan

Physics of low-dimensional systems holds a lot of promise for technology. Among the various emerging materials, transition metal dichalcogenide materials are heralding a new era in optoelectronics and valleytronics owing to their unique properties. Photo-induced dynamics in these systems is mostly studied from the perspective of individual quasi-particles—excitons, bi-excitons, or, even, trions—their formation, evolution, and decay. The role of multi-body and exciton dynamics, the associated collective behavior, condensation, and inter-excitonic interactions remain intriguing and seek attention, especially in room-temperature scenarios that are relevant for device applications. This paper reports on novel findings on the formation and decay of an unexpected electron–hole quantum liquid phase at room-temperature on ultrafast timescales in multi-layer MoS2 nanoparticles, evidenced through femtosecond broadband transient absorption spectroscopy. The studies presented here reveal the complete dynamical picture: The authors employ a successful physical model using a set of coupled nonlinear rate equations governing the individual populations of these constituent phases to extract their contributions to bandgap renormalization. Beyond the observation of the electron–hole liquid-like state at room temperature, this work reveals the ultrafast dynamics of photo-excited low-dimensional systems arising out of collective many-particle behavior and correlations. The results of our numerical modeling and experiments on the formation and evolution of the excitonic condensates lead to the identification of this new paradigm, opening up ample scope for harnessing the electron–hole liquid at room temperature, in likely quantum devices.

The paper can be seen at