Line shape simulation and saturated absorption spectroscopic measurement of Rb–D2 transition

A theoretical model based on rate equations of a four-level atom with a common ground level and three closely spaced upper levels interacting with a standing wave has been developed and solved numerically to simulate the saturated absorption spectrum of rubidium. Doppler-free and collision free Lamb dip Rb–D2 transitions were recorded by using an external cavity diode laser spectrometer operating at 780 nm. The simulated spectra could reproduce the observed spectrum very well. The value of Rabi-frequency and the saturation parameter could be evaluated.