Dr. Rajan is a currently the Director of Centre for Engineering Research in Intelligent Sensors and Systems (CeRISS) and also a Reader at Cardiff Metropolitan University, Cardiff. Prior to this he was a Senior Lecturer at the University of Wollongong and a Senior Researcher at UNSW Sydney. His research and teaching expertise and interests includes optical fibre sensors and its applications in biomedical engineering, FBG interrogation systems, photonic crystal fibre sensors, polymer fibre sensors, smart structures and materials and physics of photonic devices.

He has published over 150 articles in journals, conferences and as book chapters and two patents are also granted. He is also the editor of the books “Optical Fiber Sensors:- Advanced Techniques and Applications” and "Structural Health Monitoring of Composite Structures using Fiber Optic Methods", both published by CRC Press. He is also an Associate Editor of the journal 'Frontiers in Sensors' and is an editorial board member of the journal 'Sensors' and a reviewer for more than 30 scientific journals. He is also an assessor for funding applications of the Portugal Science Foundation, Poland Science Foundation, Czech Science Foundation and Australian Research Council. He also serves as a technical program committee member of conferences in the area of optical fiber sensors and smart structures.