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Entry  Sat Jun 1 09:46:00 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source 
    Reply  Fri Jun 7 16:32:59 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source Lock_in_amplifier_moku_lab.jpgFM_noise.pdf
       Reply  Thu Jun 13 22:53:25 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source FM_noise_new_.pdfMokulab.m
Message ID: 2360     Entry time: Fri Jun 7 16:32:59 2019     In reply to: 2358     Reply to this: 2362
Author: Anjali 
Type: Update 
Category: 2micronLasers 
Subject: Frequency noise measurement of 2 micron source 

Attachment # 1 show the schematic of the lock in amplifier configuration used in Moku lab. We saved the in phase and quadrature components.

In phase =cos\left ( \right \omega_o\tau+\Delta\phi(t))

quadrature =Sin\left ( \right \omega_o\tau+\Delta\phi(t))

where \omega_0  corresponds to 2 -micron , \tau is the delay time in the delay fiber  and \Delta\phi(t)=\phi(t) - \phi(t-\tau).

 \phi(t) is the phase noise of the laser. 

From the inphase and quadrature component \Delta \phi(t)value is extracted. So, we are actually extrating the combined effect of phase noise of laser as well the phase noise due to fiber length fluctuations due to environmental fluctuations. ASD of this is converted to frequency noise in Hz/rt Hz. Attachment # 2 shows the frequency noise estimated from two sets of measurements. This curve exhibit a 1/f characteristics from about 240 Hz upto 30 kHz

Quote:

[Anchal, Anjali]

We tried the Lock in amplifier in Moku lab for the frequency noise measurement. In this case, the output of the photo detector , after dc block and one stage of amplification, is fed into  input 1 of Moku. It gives out the inphase and quadrature component. We have saved the data. I will process the data offline and update later.

 

Attachment 1: Lock_in_amplifier_moku_lab.jpg  661 kB  Uploaded Fri Jun 7 17:44:45 2019  | Hide | Hide all
Lock_in_amplifier_moku_lab.jpg
Attachment 2: FM_noise.pdf  36 kB  Uploaded Fri Jun 7 17:44:56 2019  | Hide | Hide all
FM_noise.pdf
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