Interferometric autocorrelation of sech^2 pulse?

[IcedCoffee]

I know that from intensity autocorrelation, I simply need to divide the FWHM by 1.53 for sech2 pulses.

But I can't seem to be able to find any reference on how to get pulse width from interferometric autocorrelation signal.

Can someone help me?

 

[Baluncore]

What is the difference between "interferometric autocorrelation" and "intensity autocorrelation"?

 

[Andy Resnick]

Summary:: How do I get the pulse width from interferometric autocorrelation?

I know that from intensity autocorrelation, I simply need to divide the FWHM by 1.53 for sech2 pulses.

But I can't seem to be able to find any reference on how to get pulse width from interferometric autocorrelation signal.

Can someone help me?

I assume you meant '"field autocorrelation" instead of "Intensity autocorrelaton". What was your reference regarding "I know that from intensity autocorrelation, I simply need to divide the FWHM by 1.53 for sech2 pulses."? Was that numerical factor derived in your reference?

 

[IcedCoffee]

What is the difference between "interferometric autocorrelation" and "intensity autocorrelation"?

Intensity autocorrelation uses second harmonic generation from two non-collinear beam. It cannot resolve the fringes of a multi-cycle pulse.
Interferometric autocorrelation uses two collinear beam. The generated second harmonics beam is thus collinear with the two beams, and is affected by interference pattern.

https://en.wikipedia.org/wiki/Optical_autocorrelation

 

[IcedCoffee]

I assume you meant '"field autocorrelation" instead of "Intensity autocorrelaton". What was your reference regarding "I know that from intensity autocorrelation, I simply need to divide the FWHM by 1.53 for sech2 pulses."? Was that numerical factor derived in your reference?

There seems to be some difference between "field autocorrelation" and "interferometric autocorrelation" - the latter uses second harmonic generation while the first directly measures the pulse itself. As for the reference, I couldn't find the detailed derivation but I believe taking an autocorrelation of sech2 envelope can be done.

https://www.brown.edu/research/labs...ch.labs.mittleman/files/uploads/lecture14.pdf

 

[Andy Resnick]

There seems to be some difference between "field autocorrelation" and "interferometric autocorrelation" - the latter uses second harmonic generation while the first directly measures the pulse itself. As for the reference, I couldn't find the detailed derivation but I believe taking an autocorrelation of sech2 envelope can be done.

https://www.brown.edu/research/labs...ch.labs.mittleman/files/uploads/lecture14.pdf

Slides 15, 17-21 have the relevant calculations; are you able to verify the numerical factors on your own?

 

[OpticallyLam]

I don't think the pulse shape is as important when doing interferometric autocorrelation trace to measure the pulse duration. When working with IAC:
1. Calculate the "real time" of the fringe spacing (Which should be 2*lambda/c for a double-pass configuration).
2. Then you measure the fringe spacing of what you measured with the oscilloscope - spacing in time between 2 fringes (which should give you a time in ms).
3. The ratio of 1 and 2 is the calibration factor. Multiply that by the FWHM of your oscilloscope measurement to get the FWHM of the real pulse width.