Thin-cell sub-Doppler spectroscopy by spatially separated beam method and pump-probe method

We experimentally demonstrate two methods that improve the resolution of sub-Doppler spectroscopy using a 1 mm thick vapor cell. The linewidths of the observed spectra are approximately 1 order of magnitude narrower than the Doppler width. The first method involves using a 1 mm thick cell filled with Rb atomic vapor and two spatially separated laser beams. By employing the same principle, we also demonstrate that it is possible to achieve the same resolution by using the pump and probe pulses of a single beam. The latter method enables us to construct a simple and robust optical setup for sub-Doppler spectroscopy. OCIS codes: 300.6210, 300.6260.