Faraday rotation and ellipticity spectroscopy between excited states of Rb vapor: Theory and experiment

The Faraday rotation and ellipticity spectra of rubidium $5{P}_{3/2}\ensuremath{\rightarrow}4{D}_{5/2}$ transition in a magnetic field have been calculated and experimentally measured. By using the rotating quarter-wave plate method, the Stokes parameters of the $5{P}_{3/2}\ensuremath{\rightarrow}4{D}_{5/2}$ near-resonant probe light are measured to obtain the Faraday rotation and the ellipticity. The variation of the rotation and the ellipticity spectra is analyzed in different magnetic fields, temperatures, and pump powers. The polarization rotation over 50 deg in 1529 nm with negligible elliptical distortion is obtained. Our study of the Faraday effect between excited states of atoms broadens the available wavelength of the Faraday effect in applications.