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 Sat Jun 1 09:46:00 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source Fri Jun 7 16:32:59 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source Thu Jun 13 22:53:25 2019, Anjali, Update, 2micronLasers, Frequency noise measurement of 2 micron source
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
 Attachment 2: FM_noise.pdf  36 kB  Uploaded Fri Jun 7 17:44:56 2019
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