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d2:quick_start_opls [2018/06/06 16:07]
Michael Radunsky [D2-135 Locking]
d2:quick_start_opls [2019/03/08 10:24] (current)
Michael Radunsky [D2-250 or D2-150 Alignment]
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 At this point you should have two lasers temperature stabilized and running at their operating current. The two lasers should be within a few GHz of the same frequency of each other. (If unsure of the laser frequency, you can use a spectroscopy module to get one laser on transition and then temporarily move the spectroscopy module to the other laser to get it near the same transition.) At this point you should have two lasers temperature stabilized and running at their operating current. The two lasers should be within a few GHz of the same frequency of each other. (If unsure of the laser frequency, you can use a spectroscopy module to get one laser on transition and then temporarily move the spectroscopy module to the other laser to get it near the same transition.)
  
-===== D2-150 Alignment =====+===== D2-250 or D2-150 Alignment =====
  
 //This section assumes you are using the [[d2:​heterodyne_module|D2-150 Heterodyne Module]] to obtain an optical beat note between two lasers. If you have obtained an optical beat note by other methods, please skip this section.  ​ //This section assumes you are using the [[d2:​heterodyne_module|D2-150 Heterodyne Module]] to obtain an optical beat note between two lasers. If you have obtained an optical beat note by other methods, please skip this section.  ​
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 === First Laser Alignment === === First Laser Alignment ===
  
-Use a power meter to measure the power out from the fiber connected to the D2-150. Block the laser that has two adjustments and measure the power from the laser with one adjustment that gets coupled into the fiber. Use the two adjustments on the beam splitter that affects the laser position to maximize the power into the fiber. If you cannot measure any light from the fiber, it is often helpful to put light into the fiber (opposite direction from how the system operates) and see how well that light gets back to the laser. Adjust the same beam splitter so the light is aimed directly at the laser source. This should get the alignment close enough to measure the power in the fiber to use for further optimization. Aim for 500 μW of power although a few hundred microwatts should be sufficient. <html><​span style="​color:red">The detector in the D2-160 or D2-135-FC can be damaged by more than 1 mW input power, so be careful not to couple in too much light.</span></​html>+Use a power meter to measure the power out from the fiber connected to the D2-150. Block the laser that has two adjustments and measure the power from the laser with one adjustment that gets coupled into the fiber. Use the two adjustments on the beam splitter that affects the laser position to maximize the power into the fiber. If you cannot measure any light from the fiber, it is often helpful to put light into the fiber (opposite direction from how the system operates) and see how well that light gets back to the laser. Adjust the same beam splitter so the light is aimed directly at the laser source. This should get the alignment close enough to measure the power in the fiber to use for further optimization. Aim for 500 μW of power although a few hundred microwatts should be sufficient. <color red>The detector in the D2-160 or D2-135-FC can be damaged by more than 1 mW input power, so be careful not to couple in too much light.</color>
  
 === Second Laser Alignment === === Second Laser Alignment ===
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 === Finding a Beat Note === === Finding a Beat Note ===
  
-<WRAP right round box 450px><​imgcaption image1|Initial electrical connections to D2-135. ​ (As shown for D2-135-SMA. ​ For D2-135-FC, connect optical output of D2-150 directly to SC fiber input on face of D2-135.)>​{{:​d2:​quick_start_opls:​d2-135_connections.jpg?​direct&​400 |}}</​imgcaption></​WRAP>​+<WRAP right round box 450px><​imgcaption image1|Initial electrical connections to D2-135. ​ (As shown for D2-135-SMA. ​ For D2-135-FC, connect optical output of D2-150 ​or D2-250 ​directly to SC fiber input on face of D2-135.)>​{{:​d2:​quick_start_opls:​d2-135_connections.jpg?​direct&​400 |}}</​imgcaption></​WRAP>​
  
-Plug the fiber into either the D2-160 or D2-135-FC (obsolete). If using the D2-160, use a short RF SMA cable to connect the D2-160 to the D2-135-SMA. Look at the D2-135'​s Beat Note div/2 monitor on a spectrum analyzer. You should see a beat note at half the frequency difference between the two lasers. You may need to tweak the laser current on one laser to make sure the frequency difference is in range. Once you see a beat note, adjust the laser frequency until the beat note starts to broaden or disappear. When that happens, park the laser where the beat note starts to degrade and tweak the alignment of the 3 beam splitters until the beat note looks good. Repeat until you have the desired frequency ​range (typically ~10 GHz).+Plug the fiber into either the D2-160 or D2-135-FC (obsolete). If using the D2-160, use a short RF SMA cable to connect the D2-160 to the D2-135-SMA. Look at the D2-135'​s Beat Note div/2 monitor on a spectrum analyzer. You should see a beat note at half the frequency difference between the two lasers. You may need to tweak the laser current on one laser to make sure the frequency difference is in range. Once you see a beat note, adjust the laser frequency until the beat note starts to broaden or disappear. When that happens, park the laser where the beat note starts to degrade and tweak the alignment of the 3 beam splitters until the beat note looks good. Repeat until you have the desired frequency ​offset ​(typically ​up to ~10 GHz).
 ===== D2-135 Locking ===== ===== D2-135 Locking =====
  
d2/quick_start_opls.1528326430.txt.gz · Last modified: 2018/06/06 16:07 by Michael Radunsky