Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Measurement Science and Technology Volume 25 Number 5,2014.
Laura Russell1,2, Ravi Kumar1,2, Vibhuti Bhushan Tiwari1,3 and Sìle Nic Chormaic1,2,4
1 Department of Physics, University College Cork, Cork, Ireland and
2 Light-Matter Interactions Unit, OIST Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan and
3 Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, India and
4 School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa.
Abstract
We report here the first measurements on a dark magneto-optical trap (DMOT) of 85Rb atoms using an optical nanofibre (ONF) with a waist of ~1 um. The DMOT is created using a doughnut-shaped repump beam along with a depump beam for efficient transfer of cold atoms from the bright hyperfine ground state (F = 3) into the dark hyperfine ground state (F = 2). The fluorescence from the cold 85Rb atoms of the DMOT is detected by coupling it into the fibre-guided modes of the ONF. The measured fractional population of cold atoms in the bright hyperfine ground state (p) is as low as ~0.04. The dependence of the loading rate of the DMOT on cooling laser intensity is investigated and also compared with the loading rate of a bright MOT. This work lays the foundation for the use of an ONF for probing a small number of atoms in an optically-dense cold atomic cloud.
