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Entry  Fri Sep 30 17:40:03 2011, kiwamu, Update, IOO, AM / PM ratio 
    Reply  Mon Oct 3 20:02:59 2011, Suresh, Update, PSL, AM / PM ratio 
       Reply  Tue Oct 4 16:58:45 2011, Suresh, Update, PSL, AM / PM ratio 
Message ID: 5588     Entry time: Fri Sep 30 17:40:03 2011     Reply to this: 5606
Author: kiwamu 
Type: Update 
Category: IOO 
Subject: AM / PM ratio 

[Mirko / Kiwamu]

 We have reviewed the AM issue and confirmed the ratio of AM vs. PM had been about 6 x103.

The ratio sounds reasonably big, but in reality we still have some amount of offsets in the LSC demod signals.

Next week, Mirko will estimate the effect from a mismatch in the MC absolute length and the modulation frequency.

 


(Details)

 Please correct us if something is wrong in the calculations.

 According to the measurement done by Keiko (#5502):

        DC = 5.2 V

        AM @ 11 and 55 MHz = - 56 dBm = 0.35 mV (in 50 Ohm system)

Therefore the intensity modulation is 0.35 mV / 5.2 V = 6.7 x 10-5

Since the AM index is half of the intensity modulation index, our AM index is now about 3.4 x 10-5

According to Mirko's OSA measurement, the PM index have been about 0.2.

As a result,  PM/AM = 6 x 103

Quote from #5502

Measured values;

* DC power = 5.2V which is assumed to be 0.74mW according to the PDA255 manual.

*AM_f1 and AM_f2 power = -55.9 dBm = 2.5 * 10^(-9) W.

 

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