The quantum theory of radiation

Abstract

The Planck’s law of blackbody radiation is derived in several methods in this paper. The original Planck’s derivation in his 1900 paper, the derivation by Einstein, and another derivation based on the Bose-Einstein statistics are reviewed with comments on each derivation. Statistical properties of radiation are briefly reviewed in the second part of the paper. Different concepts of photon statistics are applied on the thermal (chaotic) light and laser light. Nonclassical properties of light that manifest its quantum nature are briefly highlighted with a short review of the experimental evidence embodied in ……….. 1-Introduction and historical perspective It was Robert Kirchhoff who first argued in 1859 that the thermal radiation of the blackbody was of a fundamental nature.1 Since that time, several attempts were made to derive a precise relation that matches the experimental results. Wien, suggested that the radiation density per