Daniel Joseph Bradley, physicist and Emeritus Professor of Optical Electronics at Trinity College, Dublin, is born on January 18, 1928 in Derry, County Londonderry, Northern Ireland.
Bradley is one of four surviving children of John and Margaret Bradley, Lecky Road, Derry. He leaves school to work as a telegraph boy but returns to education at St. Columb’s College. Following training as a teacher at St. Mary’s Training College, Belfast, he qualifies in 1947. While teaching in a primary school in Derry he studies for a degree in mathematics as an external student of the University of London, and is awarded a degree in 1953.
Moving to London where he teaches mathematics in a grammar school, Bradley decides to register for an evening course at Birkbeck College. His first choice is mathematics but as he already has a degree in the subject the admissions staff suggests that he study physics. In 1957, after four years of part-time study, he is awarded a Bachelor of Science degree in physics by Birkbeck, achieving the highest marks in his final exams in the University of London overall. He next joins Royal Holloway College as an assistant lecturer and simultaneously enrolls as a PhD student, working on Fabry–Pérot interferometer etalon-based high-resolution spectroscopy supervised by Samuel Tolansky. He receives a PhD in 1961.
Bradley is a pioneer of laser physics, and his work on the development of ultra-fast pulsed lasers adds a new and vitally important element to the capabilities of this new type of light source. In particular, working on dye lasers, he produces pulses of light as short as one picosecond (one picosecond is to a second as a second is to 31,800 years). His work paves the way for the completely new field of non-linear optical interactions. In addition, he inspires a new generation of laser scientists in Ireland and the UK, many of whom are international leaders in their fields.
Appointed to a lectureship in the physics department at Imperial College London, Bradley sets up a research programme in UV solar spectroscopy using rocket technology to reach high altitudes.
In 1963 Bradley begins work in laser physics but returns to Royal Holloway College as a reader one year later. In 1966 he is appointed professor and head of department at Queen’s University, Belfast. There he quickly establishes a space research group of international standing to do high-resolution solar spectroscopy. He attracts significant funding from a variety of agencies, allowing him to build his department into one of the world’s leading laser research centres, involving a total of 65 scientists. However, he leaves Belfast because of fears for his family’s safety as political violence escalates in the early 1970s amidst The Troubles.
Bradley returns to Imperial College London in 1973 to a chair in laser physics and heads a group in optical physics, laser physics and space optics. He is head of the Physics department from 1976 to 1980 but is frustrated by cutbacks and a rule governing the ratio of senior to junior positions, one consequence of which is that he is unable to maintain a long-established chair in optical design. He is also critical of the college administration’s handling of some departmental grant applications. He resigns in 1980 and moves to Dublin.
Among Bradley’s many lasting contributions to laser research in the UK is the setting up of one of the world’s leading research facilities for laser research, the Central Laser Facility at the Rutherford Appleton Laboratory (RAL).
Arriving at Trinity College, Dublin, Bradley decides the time is ripe to move on from laser research and development into laser applications. In 1982, with Dr. John Kelly, a chemist, and Dr. David McConnell, a geneticist, he forms a team which wins funding for a project using laser techniques to explore the structure of organic molecules like DNA and proteins. Unfortunately, however, his work at Trinity is cut short by ill health and he retires in 1984. His research on semiconductor lasers is carried on and this work on developing widely tuneable lasers for optical communications systems continues.
A member of the Royal Irish Academy, Bradley is Fellow Emeritus of Trinity College Dublin, and holds fellowships of the Royal Society, The Optical Society of America and Institute of Physics. Through time the ravages of his illness restricts his travelling and eventually he is cared for in a residential home in Dublin, where he passes away on February 7, 2010.