Controlling Atomic Excitation with Frequency-Modulated Lasers

Lirong Wang, Jie Ma, Yanting Zhao +2 more

In the present paper, ultracold cesium atoms were obtained in magnetic optical trap using the laser cooling technology. The number of ultracold atoms is 10(7). The temperature of ultracold atoms is about 200 μK and the diameter of the ultracold atoms cloud is about 400 μm. The ultracold cesium molecules of excited states were formed using the photoassociation of ultracold atoms. The resolution of vib-rotational spectrum was studied under different scan rates of photossociation laser in the experiment. The resolution of vib-rotational spectrum becomes high when the scan rate of photossociation laser becomes slow. The cold atoms fluorescence was obtained using the high sensitive avalanche photo detector and the high resolution vib-rotational spectrum of ultracold cesium molecule in its first excited state of with dissociation limit long range state was obtained. The ultracold ground molecule was formed by controlled Raman photoassociation and the photoassociation laser must be locked to atom-molecular hyperfine transitions. The ultracold atoms photoassociation spectrum was modulated using ultra-low frequency. The first-order differential signal was optimized by changing modulation amplitude and modulation frequency. It provides a feedback signal to correct error of the laser. The laser frequency satisfies experimental requirement to form ultracold ground molecules using the controlled Raman photoassociation. This work is important for studies of ultracold atoms and molecules in confined space.

V. I. Balykin, Vladilen S Letokhov, Vladimir G. Minogin

Wolfgang Jitschin

Valery Alexandrovich Astapenko

The paper is devoted to the theoretical investigation of the phase control of atomic photo-excitation in discrete energy spectrum under the action of bichromatic laser field with the frequency ratio 1:2 in the presence of stationary electric field. The calculations are made for the case of alkali atoms. It is shown that the phase modulation of the photo-excitation strongly depends upon the electric field strength and the ratio between the intensities of the monochromatic components of the radiation. The optimal range of parameters for the effect observation is determined.

Mark Edwards, Charles W. Clark

Joseph S. Melinger, Anand Hariharan, Suketu R. Gandhi +1 more

Optical excitation of material transitions by adiabatic passage with frequency modulated (chirped) laser pulses is a useful spectroscopic tool.1,2 Here we demonstrate that picosecond frequency modulated laser pulses produce more efficient population transfer, and more selective excitation than equivalent (same spectral bandwidth) nearly transform limited laser pulses. We apply frequency modulated pulses to gas-phase and condensed phase systems. We also point out the "robustness", or insensitivity of the properties of the material excitation to the parameters of the laser field, that is inherent to the adiabatic process. The robustness obtainable by adiabatic passage will ultimately prove useful to laboratory applications of theoretical schemes which require frequency modulated ultrashort laser pulses to control chemical reaction dynamics.3