E field phase matching at interface, deriving Snell's Law

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SUMMARY

The discussion centers on understanding phase matching at the interface in optics, specifically in relation to Klein and Furtak's unnumbered equation on page 75 and Jackson's equation 7.34 in "Classical Electrodynamics." The user seeks clarification on the absence of arbitrary phase factors in the equations governing the electric field components at the interface, which is defined as the z=0 plane. The user notes that while they grasp most of the derivation, the boundary conditions remain unclear, particularly regarding the necessity of phase matching at the origin.

PREREQUISITES
  • Familiarity with Klein and Furtak's "Optics" textbook
  • Understanding of Jackson's "Classical Electrodynamics" 2nd edition
  • Knowledge of wave vector notation and boundary conditions in optics
  • Basic concepts of phase matching in electromagnetic waves
NEXT STEPS
  • Review Griffiths' arguments in chapter 7 regarding phase matching
  • Study the derivation of Snell's Law in the context of wave propagation
  • Explore boundary conditions for electromagnetic waves at interfaces
  • Investigate the implications of arbitrary phase factors in wave equations
USEFUL FOR

Students and researchers in optics, particularly those studying wave propagation and boundary conditions, as well as anyone seeking to deepen their understanding of phase matching in electromagnetic theory.

Cruikshank
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I'm studying optics on my own and have gotten very stuck on page 75 of Klein and Furtak, the unnumbered equation. Specifically, I don't understand why there aren't arbitrary phase factors inserted; the equation does not look general enough. I checked in Jackson, 2nd edition Classical Electrodynamics, and on page 279 Jackson simply states in equation 7.34 that the phases have to match at the origin. There isn't much there, just a declaration, and I don't understand why it should be true. Any pointers?

I've gotten nearly everything else in that derivation, but really I must have written 50 pages of equations trying to solve these boundary conditions.

Incoming wave vector k = n - iK (propagation and attenuation) Reflected wave has double prime, transmitted wave has single prime. Klein and Furtak simply write (for E_t, t is tangential, consider it a variable for which x or y can be substituted:)

E_t*e^-i(k_x x) + E"_t*e^-i(k"_x * x + k"_y*y) = E'_t*e^-i(k'_x * x + k'_y * y)

The interface is the z=0 plane, so I see why there are no z factors. But I would have inserted arbitrary phases on E' and E". Why are they not needed?
 
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Cruikshank said:
E_t*e^-i(k_x x) + E"_t*e^-i(k"_x * x + k"_y*y) = E'_t*e^-i(k'_x * x + k'_y * y)

The interface is the z=0 plane, so I see why there are no z factors. But I would have inserted arbitrary phases on E' and E". Why are they not needed?

IIRC, Griffiths gives a decent argument (middle of chapter 7 I think).
 

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