Childhood & Early Life
He was born on May 3, 1902, in Guebwiller in Alsace (at that time under the German Empire, presently in France) to Fréderique Michel Kastler and his wife Anne Catherine Kastler.
He did initial studies at his native place and then attended the Oberrealschule of Colmar, Alsace, that became the ‘Lycee Bartholdi’ in 1918 following Alsace’s reversion to France after the ‘First World War’.
His interest in science was infused by his science and mathematics teachers from an early age. After reading the book on atomic structure and spectral lines by Arnold Sommerfeld, he got introduced to the principle of conservation of momentum that is used in exchanging energy between radiation and atoms, a foundation that guided him all through his research career.
After completing high school education in 1921 he joined ‘École Normale Supérieure’ in Paris from where he completed BS in Physics in 1926.
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From 1926 to 1931 he served the Lycée of Mulhouse as a teacher of physics.
He then delved into an academic career in higher education and joined the ‘Bordeaux Faculty of Science’ as an assistant of Professor Pierre Daure. He served there from 1931 to 1936.
Thereafter completing his teaching duties he would utilise his free time into conducting research work. He was introduced to experimental spectroscopy by Professor Daure. Kastler worked in the area of optical spectroscopy for years, especially on Raman Spectroscopy and atomic fluorescence.
From 1936 to 1938 he remained a physics lecturer at the ‘Blaise Pascal University’ in Clermont-Ferrand. In 1937 he turned his focus to the luminescence of sodium atoms in the upper atmosphere. He succeeded in establishing that sodium vapour can absorb the D line of the twilight sky. He along with his colleague Jean Bricard showed that the D line is polarized when the emission method is one of optical resonance generated by solar radiation.
In 1938 he joined the ‘University of Bordeaux’, where he was inducted as a university professor and served the position till 1941.
After being advised to return to École Normale Supérieure’ in Paris by Georges Bruhat, Kastler joined there as a teacher of physics in 1941 and became a professor of physics in 1945. He was allocated a chair there in 1952. He served the school till 1968 where he trained, guided and collaborated with many students who went on to achieve great heights in the field of optics.
In the midst of German occupation French scientists remained detached from rest of the world and it was not until 1945 that they could manage to send students in other countries of the West to acquire knowledge of recent scientific developments.
Kastler conducted most of his research work at the ‘Ecole Normale Supérieure’ where post war he and his student Jean Brossel formed a small research team on spectroscopy.
The duo founded a spectroscopic laboratory the ‘Laboratoire de spectroscopie Hertzienne de l'ENS’ in the Department of Physics of École Normale Supérieure in 1951. The lab which was later named as ‘Laboratoire Kastler-Brossel’ in 1994 in their honour has a second site on the Jussieu campus.
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Kastler and Brossel collaborated together and researched on areas like spectroscopy, the study of the interaction between electromagnetic radiation and matter’; quantum mechanics, a fundamental field in physics which deals with methods that involve photons and atoms; and the interaction between atoms and light.
Kastler and Brossel suggested the ‘double resonance method’ that combines magnetic resonance and optical resonance. Kastler then developed the procedure of ‘optical pumping’ a method where atoms are excited in a specific substance such that they achieve greater states of energy. As re-emission of the light energy that is used to excite the atoms occurs, the optical pumping system emerged to be an important procedure that aided in furthering the development of the theory of lasers and masers.
‘Laboratoire Kastler-Brossel’ played a significant role in developing the field of atomic physics in the country and remains one of the leading research labs in the field of fundamental physics of quantum systems.
From 1968 to 1972 Kastler served the ‘National Center for Scientific Research’ in France as its Director of Research.
He was associated with ‘French Academy of Sciences’ and ‘French Physical Society’ and was Foreign Member of ‘Polish Physical Society’, ‘Royal Flemish Academy of Belgium’ and ‘Optical Society of America’.
He received honorary doctorates from the ‘University of Louvain’ in 1955’, ‘University of Pisa’ in 1960 and ‘University of Oxford’ in 1966.
He had written poetry in German language and in 1971 he published ‘Europe, ma patrie: Deutsche Lieder eines französischen Europäers’ (‘Europe, my fatherland: German songs of a French European’).
He remained President of the Board of ‘Institut d'optique théorique et appliquée’.
‘Action Against Hunger’, an NGO which was set up in 1979 by a group of French doctors, writers and scientists with the objective of ending world hunger selected Kastler as its first Chairman.
Personal Life & Legacy
He married Elise Cosset, an ex-student of ‘École Normale Supérieure’, in December 1924. By profession she was a history teacher in secondary schools.
They were blessed with three children, Daniel (born in 1926), who became a Professor of Physics at the Faculty of Science in Marseilles; Mireille (born in 1928), who is by profession an ophthalmologist working in Paris; and Claude-Yves (born in 1936), who is a Russian language teacher at the Arts Faculty in Grenoble.
Kastler passed away on January 7, 1984, at the age of 81 years in Bandol, France.