A dual-wavelength bandpass Faraday anomalous dispersion optical filter operating on the D1 and D2 lines of rubidium

A dual-wavelength bandpass Faraday anomalous dispersion optical filter (DW-FADOF) operating at both the D1 and D2 lines of rubidium is experimentally demonstrated. The effects of certain system parameters, such as the incident laser power, magnetic field strength, and atomic density, on the performance of the filter are experimentally and theoretically investigated. Through elaborate simulation, an appropriate set of system parameters is selected, and the DW-FADOF achieves peak transmittance of 37.4% with a figure of merit (FOM) of 0.10 GHz−1 in the D1 line and 77.9% with a FOM of 0.33 GHz−1 in the D2 line, simultaneously. This FADOF provides transmission bands covering both two typical atomic transitions, and it can be used as a dual signal carrier. Due to the integration and minimization of loss, the results confirm the significant application potential of this filter in wavelength division multiplex communication and weak signal extraction.