Ultra-narrow bandwidth atomic filter based on optical-pumping-induced dichroism realized by selectively saturated absorption

We report an ultra-narrow bandwidth atomic filter based on optical pumping induced dichroism. Induced-dichroism-excited atomic line filters in previous research used a pump to populate atoms on special Zeeman sub-levels, so only one sigma component of the probe undergoes absorption while the other one can pass through the medium freely because of dipole forbidden. Unlike in previous research, we proposed a novel method to get circular dichroism realized by “selectively” saturated absorption in rubidium. In the experiment, we observed three transmission peaks: the principle of the first two is the same as the previous research, while the third one is realized by selectively saturated absorption, which has a peak transmission of 14.9% with 61 MHz bandwidth.