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Message ID: 411     Entry time: Mon Nov 29 14:34:35 2010
Author: tara 
Type: Notes 
Category: NoiseBudget 
Subject: noise budget update 

I updated the noise budget, see the plot below. LO phase noise and RIN are updated in this version

 The code is also attached below.

1) LO noise

I used Megan's LO phase noise measurement, converted it to freq noise and added it to the nb.

Note that the plot is from 160MHz carrier and 100Hz range.

She has data for 160 MHz, 100Hz range and 160MHz, 10Hz range. There is no measurement at 100kHz range which I used for my measurement.

At larger range the LO noise is higher, and the shape of LO noise between two ranges are different at high frequency (1k and above).

 My beat measurement was taken at 160MHz, 100kHz range. So the actual LO noise in the measurement will be higher,

but should not be more than an order of magnitude. 

I decide to keep it as it is,and that should give us the lower limit of the current LO phase noise.

 

2)RIN

Second, I injected intensity modulation at 100Hz and measure the beat to get the conversion from RIN -> fbeat.

This is not accurate, since the output adjustment that I used for intensity modulation also changes the frequency as well, but

it should give us some limit how intensity couples to fbeat.

Right now we cannot purely modulate the intensity, and AOM will be added to modulate/stabilize the intensity soon.

Attachment 1: nb_2010_11_29.png  45 kB  | Hide | Hide all
nb_2010_11_29.png
Attachment 2: beat_and_RIN_2010_11_29.mat  121 kB
Attachment 3: psl_nb_2010_11_29.m.zip  5 kB
Attachment 4: Phase_Noise_160MHz_100HzRange_1.txt.zip  94 kB
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