How to calculate mode overlap with I(x,y) rather than E(x,y)

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SUMMARY

The discussion focuses on calculating mode overlap using intensity distribution I(x,y) instead of the electric field E(x,y) in a multimode rectangular waveguide coupled to SMF28 fiber. The traditional method involves cross-correlation of electric fields, represented by the formula η = (∫ E1 * conj(E2))^2 / (∫ |E1|^2 * ∫ |E2|^2). The participant questions whether taking the square root of the intensity distribution and assuming the imaginary part is zero can yield valid results, suggesting the use of spatial symmetry for mode mapping.

PREREQUISITES
  • Understanding of waveguide optics and multimode propagation
  • Familiarity with intensity distribution and electric field concepts
  • Knowledge of cross-correlation techniques in optical physics
  • Basic principles of mode mapping in optical systems
NEXT STEPS
  • Research the implications of using intensity distributions in mode overlap calculations
  • Explore advanced techniques for mapping intensity distributions to known modes
  • Study the mathematical foundations of cross-correlation in optical fields
  • Investigate the properties of spatial symmetry in optical modes
USEFUL FOR

Optical engineers, physicists working with waveguides, and researchers involved in fiber optics and mode analysis will benefit from this discussion.

Fixar Frazze
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Hi

I have a waveguide that is rectangular and multimode that I but-couple to a standard telecom SMF28 fiber. I have imaged the output of the waveguide and the fiber with a 25X microscope objective onto the chip of an IR-camera. Usually the mode overlap is calculated by cross-correlation of the electric field (E(x,y)). Like

\eta=\frac{(\int E_1*conj(E_2))^2}{\int |E_1]^2*\int |E_2]^2}

Now however I only have access to the intensity distribution I(x,y).

What do you think, can I justs take the square root of the intensity and perform the calculation and pretend the imaginary part is equal to zero?
 
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