We performed high-resolution Doppler-free two-photon spectroscopy of Yb atoms in an effusive atomic beam and generated a cascade of two photons at 611.3 nm (idler) and 555.8 nm (signal) with a narrow bandwidth of 37 MHz. Efficient population transfer from the ground state (6s2 1S0) to the upper state (6s7s 1S0), where direct transition at 291.1 nm is dipole forbidden, was achieved through a resonant two-photon excitation enhanced by the electromagnetically-induced transparency mediated by the intermediate state (6s6p 1P1). From the upper state, a cascade of two photons in sequence was emitted via the spin triplet state (6s2 3P1). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields explain quantitatively the experimental results for the dependences of the idler and the signal beam intensities on the various parameters of the driving fields. We report on the generation of a cascade of two photons with fluxes at the level of a few times 106 photons/s detected at a solid angle of 0.01 sr.
- Correlated two-photon generation
- Doppler-free two-photon spectroscopy
ASJC Scopus subject areas
- Physics and Astronomy(all)