Rodney Loudon FRS (25 July 1934 – 25 December 2022) was a British physicist, best known for his work in quantum optics.

He received his Master of Arts (1956) and Doctor of Philosophy (1959) degrees from the University of Oxford, where he was a member of the Brasenose College.

He has published more than 190 papers and 3 books, one of which (the three editions of The Quantum Theory of Light) is recognized internationally and has been translated into Russian and Japanese.

[4] His early work on excitons, phonons and magnons and his later treatments of non-classical effects in the statistical properties of light have attracted many citations.

He has also worked at British Telecom, Royal Radar Establishment, Bell Telephone Laboratories and Radio Corporation of America, and he has been a consultant to these organisations over several years, contributing to both applied and fundamental research.