3 votes

What is a laser spectrum?

You are probably talking about the helium-neon laser: The best-known and most widely used He-Ne laser operates at a wavelength of $632.8$ nm (in air), in the red part of the visible spectrum. This ...
Thomas Fritsch's user avatar
2 votes

Why fiber optic Sagnac interferometers don't produce multiple interference fringes

The fibre is a single mode fibre and the phase is therefore associated with the mode as a whole varying along the longitudinal direction. The interference thus only determines which output port gets ...
flippiefanus's user avatar
  • 14.6k
1 vote

Measuring duration of ultra-short laser pulses

A spectrometer gives the amplitude of each Fourier coefficient, but not the phase. Phase matters. In the most extreme example, if you add all frequencies with the right phase, you get a delta function....
mmesser314's user avatar
  • 38.7k

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