Single-Photon Atomic Cooling - Raizen Lab - The University of ...

lenses is 150 mm, however the spacing is adjustable, allowing us to control the
beam curvature and hence the location of the beam waist after it is focused
by a 63.5 mm lens into the lower chamber glass cell. The power needed in the
depopulation beam is very small, typically around a few nanowatts.
3.2.2 Far-Detuned Laser
We use far-detuned laser beams to create optical dipole traps to confine
atoms. A discussion of the theory used to estimate the depth of these traps is
given in Sec. 2.5.1. There it was seen that in the limit of negligible saturation
and a frequency detuning much larger than the fine structure splitting, the
optical dipole potential is given by
Udip(r) = 3πc2
2ω 3 0
Γ
∆ I(r).
The laser used to create the optical dipole traps, the Verdi V10, is a
commercially available turn-key system manufactured by Coherent, Inc. This
laser outputs a single-mode (both longitudinally and transversely) with up to
10 W of power at 532 nm. The linewidth is specified to be < 5 MHz and was
measured over 50 ms with a thermally stabilized reference etalon. The output
beam diameter and divergence are specified to be 2.25 mm and < 0.5µrad,
respectively. The beam is vertically polarized and nearly Gaussian (M 2 < 1.1).
The pointing stability, power stability and RMS noise are specified as < 2µrad
/ ◦ C, ±1% and < 0.03%, respectively. These laser parameters are summarized
in Table 3.1.
118