Characterisation of grating properties for MOTs at multiple wavelengths and laser cooling Rb on the 5S1/2 - 6P3/2 transition at 420nm

This thesis presents progress towards making a blue magnetic-optical trap (MOT) utilizing a reflective diffraction grating, a 780nm and a 420nm laser. Taking advantage of the narrower line width of the 6P3/2 state, 420nm lasers can theoretically make a factor of 10 colder MOT than those using 780nm ones based on the Doppler limit. However, considering the low capture rate caused by this narrower linewidth, 87Rb atoms are planned to be captured using a MOT on the 5S1/2 - 5P3/2 transition at 780nm for pre-cooling and then transferred to a MOT on the 5S1/2 - 6P3/2 transition at 420nm. As the very first group intending to make a 420nm grating-MOT, we studied the behaviour (diffraction efficiency, polarisation efficiency) of diffraction gratings with different etch depth, coating material, duty cycle to find suitable gratings which work for both 780nm and 420 nm. To investigate other potential laser sources, 423nm laser diode samples were tested to explore the possibility of reaching the desired wavelength (420.297 nm) for cooling.

Name dc:type.qualificationname

mres

Level dc:type.qualificationlevel

masters-pg

Grantor dc:publisher.institution

University of Strathclyde

Year dc:date.issued

2017

Author dc:creator

• Li, Wenbo

Advisors dc:contributor.advisor

• Griffin, Paul
• Arnold, Aidan

DOI

10.48730/bby6-gb15

Identifier

T14933

Author Identifier

201573732

OAI identifier oai:identifier

oai:strathclyde:6108vb28f