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

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then passes through an AOM driven at 80 MHz. A portion <strong>of</strong> the 0 th order<br />

beam is sent to a Fabry-Perot interferometer to monitor its spectrum. <strong>The</strong><br />

remaining portion <strong>of</strong> the 0 th order beam passes through a second AOM driven<br />

at 80 MHz. <strong>The</strong> first order spot from this AOM is shifted into resonance with<br />

the |F = 2〉 → |F ′ = 3〉 transition (with the correct injection frequency) and is<br />

used as the push beam. This AOM is used as a fast shutter to block the beam<br />

when not wanted. We do this by blocking the drive signal with an rf voltage<br />

controlled attenuator. However even with full attenuation some light is present<br />

in the first order. To completely block this light a slower (∼ 2 ms) mechanical<br />

shutter is used. <strong>The</strong> zeroth order beam from the second 80 MHz AOM double<br />

passes a 56 MHz AOM and is used for vertical absorptive imaging. <strong>The</strong> first<br />

order beam from the first 80 MHz AOM passes through an AOM driven at<br />

424 MHz. <strong>The</strong> zeroth order beam from this AOM is used as the upper MOT<br />

horizontal beams. <strong>The</strong> −1 st order beam is used as the depopulation beam in<br />

the single-photon cooling process. More details on this beam can be found in<br />

Sec. 3.2.1.7.<br />

3.2.1.4 Upper MOT Diagonal Slave Laser<br />

This slave laser is used primarily to produce the upper MOT diagonal<br />

beams. <strong>The</strong> excess power is used to create the optical pumping beam and<br />

the horizontal absorptive imaging beam. <strong>The</strong> distribution <strong>of</strong> power from this<br />

laser is illustrated in Fig. 3.14. This beam also starts by passing through an<br />

anamorphic prism pair and optical isolator. After that it passes through an<br />

110

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