Coherent forward-scattering spectra of Cs I 852.1-nm with a light-emitting diode and a diode laser in a Voigt configuration

The coherent forward scattering (CFS) spectra of Cs I 852.1-nm line was measured using a CFS spectrometer in a Voigt configuration with an electromagnet and temperature-controlled Cs gas cell. A light-emitting diode (LED) and a diode laser (DL) were used as broadband and narrowband light sources, respectively. The relation of the CFS intensity and external magnetic field (B) was log–log plotted. Results showed that the CFS signal intensities depend on B to the power of 1.69 ± 0.38 and 1.51 ± 0.06 for DL and LED, respectively. A higher external magnetic field should be favorable when a broadband light source is used. However, the CFS signal decreased with an LED source as B approached 300 mT. To explain this observation, the hyperfine Paschen–Back splitting pattern of the Cs I 852.1-nm transition was calculated. The decrease in the CFS signal was caused by the level-crossing of π- and σ-components of the Cs I 852.1-nm transition in a Voigt configuration.