Faraday Rotation of Broad-Spectrum Polychromatic Light and Its Quantum Description

For polychromatic light having a broad spectrum width, the effective Faraday rotation angle ≪¿F≫ is defined operationally as ≪¿F≫ = ¿¿^¿FS^¿P^¿d¿/¿s^¿p^¿d¿. Here ¿^¿, S^¿ and P^¿ are the Faraday rotation angle, photodetector sensitivity, and light intensity, respectively, at wavelength ¿. Integration is performed over the spectral width of the polychromatic light. From classical electromagnetic wave theory we derived the above equation, to which we gave a consistent quantum description of the photon image. Experiments on an FR-5 glass sample using a halogen lamp as a polychromatics light source supported our calculations.