Ultranarrow bandwidth nonlinear Faraday optical filter at rubidium D_2 transition

摘要

We demonstrate a narrowband optical filter which operates on the 52S1/2 to 52P3/2 transition at 780 nm in rubidium vapor based on optical-pumping-induced dichroism combined with Faraday anomalous dispersion effects. Its peak transmission is 18.4(2)% at the 52S1/2,F = 2 to 52P3/2,F′ = 1,3 crossover transition,whereas at the 52S1/2,F = 2 to 52P3/2,F′ = 2,3 crossover transition the transmission is 18.6(2)%. Both transitions have a bandwidth(full-width at half-maximum of peak transmission) as narrow as 24.5(8) MHz,which is remarkably improved compared with the narrowest bandwidth as we know. This technique can also be applied to other alkali atoms.