Laser-induced birefringence in a wavelength-mismatched cascade system of inhomogeneously broadened Yb atoms

We report the observation of laser-induced birefringence (LIB) in a wavelength-mismatched cascade system (J=0↔J=1↔J=0 transitions) of inhomogeneously broadened ytterbium atoms with strong pump and probe fields. We investigate the transmission spectrum of two circular polarization (σₚ⁺ and σₚ^-) components of strong probe field at fixed frequency, depending on the detuning of a circularly polarized (σc^-) coupling field from two-photon resonance. We find that the σₚ⁺ (σₚ^-) polarized component exhibits a narrow electromagnetically induced absorption (transparency) spectrum. Numerical solutions of density matrix equations show qualitative agreement with experimental results. A Doppler-free dispersive LIB signal is obtained by detecting the Stokes parameter of the probe field, enabling us to stabilize the frequency of the coupling laser without frequency modulation.