Experiments to Control Atom Number and Phase-Space Density in ...

provides the beam for the upper MOT diagonal beams. The zeroth order passes through
a polarizing beam splitter cube and encounters a second 80 MHz AOM. A double pass
setup at this AOM shifts the frequency by 160 MHz, so that the laser is shifted into
resonance with the |F = 2〉 → |F ′ = 2〉 transition given the right seed frequency. This
beam is used for optical pumping. The zeroth order double passes an AOM driven
at 56 MHz. This beam is used for horizontal absorption imaging. Both beams are
deflected on the polarizing beam splitter cube. The zeroth order beam is coupled into a
Fabry-Perot cavity.
4.3.1.6 Lower MOT Slave Laser
The lower MOT slave laser provides sufficient power for all six lower MOT beams.
The beam setup is shown in figure 4.18. After passing through the optical isolator, the
beam gets diffracted into the +1st order of an 80 MHz AOM. Subsequently this beam
is split into the six lower MOT beams. The zeroth order is coupled into a Fabry-Perot
cavity to ensure single-mode operation.
λ λ
Figure 4.18: Lower MOT slave laser setup. Figure courtesy of Gabriel Price.
4.3.2 Far-Detuned Laser
A far blue-detuned laser (λ = 532 nm) creates the optical dipole trap used in the
single-photon cooling sequence. This laser is a Coherent Verdi V10, a frequency-doubled
Nd:Vanadate laser, with an output power of 10 W in a TEM00 spatial mode. The laser
linewidth is less than 5 MHz.
The trap configuration used in the single-photon cooling experiment is shown in
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