From 1941 to 1945 he studied at the ENS under Alfred Kastler and then went to the group of Samuel Tolansky in Manchester spending the years 1945–1948 and in 1948 to Francis Bitter at MIT.
In 1951 for work done at MIT, Brossel received his PhD in Paris under Kastler with a thesis on the application of double resonance methods (developed by Kastler and him) to the study of the excited states of Hg.
From 1973 to 1985 he was Director of the Physics Faculty of ENS.
In 1985 he retired and went to the University of Paris.
Brossel is known for his work on optical pumping with Alfred Kastler, with whom he founded in 1951 the spectroscopic laboratory at ENS (Laboratoire de Spectroscopie Hertzienne), which now is called the Laboratoire Kastler-Brossel.