Temperature of the Remaining Cold Atoms after Two-Step Photoionization in an super(87)Rb Vapor Cell Magneto-Optical Trap

• Published in: Chinese physics letters Vol. 31; no. 7; pp. 073401 - 1-073401-4
• Main Authors: RUAN, Ya-Ping, JIA, Feng-Dong, LIU, Long-Wei, SUN, Zhen, HUANG, Wei, XUE, Ping, XU, Xiang-Yuan, DAI, Xing-Can, ZHONG, Zhi-Ping
• Format: Journal Article
• Language: English
• Published: 01.07.2014
• Subjects: Cold atoms; Excitation; Laser cooling; Lasers; Photoionization; Power factor; Semiconductor lasers; Titanium dioxide
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/31/7/073401

The temperature of the remaining cold super(87) Rb atoms connned in a vapor cell magneto-optical trap after two-step photoioniza tion has been measured. In the two-step photoioniza tion process, the first excita tion laser is served by the cooling laser and the second excitation laser is served by a continuous semiconductor laser with a wavelength of 450nm. The results show that the temperature of the remaining cold atoms decreases as the intensity of the second excitation laser increases. Moreover, the relationship between the temperature T and number N of the remaining cold atoms generally follows a power law, while it deviates from the well-known T [infinity] N super(1/3) and the power factor is smaller than 1/3. We propose that ion-atom collisions occurring during a photoionization process strongly influence the temperature scaling law in an optically dense magneto-optical trap in the presence of an ioniza tion laser. In addition, the forced evaporative cooling due to the combined effect of the detuning of the first excitation laser and the two-step photoionization plays a role in cooling the remaining cold atoms and results in the dependence of the power factor on the detuning of the first excitation laser.