Question

How do I modulate one branch of a mach zehnder interferometer?

  • 26 October 2021
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I’m building a laser doppler vibrometer as a senior project. To better understand how interference patterns work, I wanted to simulate this. In real life I will be using an electro optic modulator on one branch of the interferometer to heterodyne a carrier signal of around 80kHz. I would like to detect a doppler shift from vibrations around 5kHz. I loaded up the mach zehnder example file and would somehow like to run one path through what would be an 80 kHz modulation and then another 5 kHz to simulate the shift vibrations. I guess I’d like to try and see if a spectrum analyzer could pick this up and see the 5 kHz shift isolated. Or maybe view it in transient. The real life project has the recombined beam fed into a photodiode, then trans-impedance amplifier, then FM demodulator to read out only the doppler shift.

 

Any insight on how to simulate a modulated beam / laser doppler vibrometer type system would be an amazing help!

 

(FYI I have not used this program before so I am not familiar with it’s features.)


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