Following a postdoctoral stay at the University of Wisconsin–Madison, he was a research scientist at Bell Labs, New Jersey for six years. He returned to Ireland in 1986 as Professor of Laser Physics in Trinity College. Producing over 140 publications, and developing a number of patents, he was a co-founder of Optronics Ireland and of campus company Eblana Photonics. He is a member of the Royal Irish Academy, the American Physical Society, the Optical Society of America, the Institute of Electronic and Electrical Engineers and Fellow of the Institute of Physics.