We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies ω1 and ω2, and Rabi frequencies ？1 and ？2, in which the first coupling field of ？1 acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of ？2, thus resulting in the doubly dressed atom.We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 52S1/2, F= 2 and 5~2P_（3/2）, F＇= 3 states of ^（87）Rb atoms in a magneto-optical trap（MOT） as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.
In most coherent imaging modality,speckle noise is a major cause that blurs the boundary of tissues and degrades the image contrast.By utilizing the unique properties of supercontinuum(SC)generated by noise-like pulses(NLPs)and a simple multi-frame averaging technique,we achieved significant speckle reduction in spectral domain optical coherence tomography(SD-OCT).We quantitatively compared the speckle of our proposed method with those of conventional swept source OCT(SS-OCT)and SD-OCT based on commercial light sources.The experimental results show that SC pumped by NLPs combined with noncoherent averaging method achieves better denoising performance in terms of contrast to noise ratio(CNR).
