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Message ID: 420     Entry time: Mon Dec 6 22:09:59 2010
Author: frank, tara 
Type: DailyProgress 
Category: BEAT 
Subject: replacing PMC, adding EAOM  

Today we 1)replaced out PMC with DMASS' PMC and get better transmission efficiency, 2) added EAOM to modulate the laser intensity

3) measured TF to see how RIN couples into laser frequency shift, it is small and not the current limiting source for now.

 

Our PMC is not very clean and get the transmission only ~60-70%. The PMC we got from DMASS is much better, now the transmission is up to ~80-90%, we have not

align it carefully yet.  After replacing the PMC, the beat noise did not change.

 

The Faraday isolator was re-installed and optimized, I used the wrong side before and dumped the beam inside the isolator, instead of outside.

A PBS and a 1/2 wave plate were installed after the PMC to adjust the power without changing the power input of the PMC, the beat noise gets higher

a bit.  I mounted the beam splitter for beat signal on a more rigid post, and aligned the two beams, then measure the beat noise.

See plot.

 Intensity modulation set was installed. The set consists of a 1/2 WP, an EAOM, a PBS. Then we amplitude modulated by sending a sine wave to

the EAOM, and measured the TF between (The excitation is sent to the EAOM)

 

1) intensity modulation and ACAV_trans_PD

2)intenisity and RCAV_trans_PD

3) intensity and beat noise

4) ACAV_trans_PD and VCO feed back to AOM

extra: we measure the TF between PMC_trans_PD and ACAV/RCAV_trans_PD, since the line width of PMC is much larger than that of RCAV/ACAV,

we can measure the TF of their poles.

 [The plot will be posted soon]

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