Sellmeier equations & group delay dispersion

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SUMMARY

The discussion focuses on converting the Sellmeier equation for refractive index into a group delay dispersion (GDD) graph. The equation provided is n^2 (λ)=1+ (B_1 λ^2)/(λ^2-C_1 )+(B_2 λ^2)/(λ^2-C_2 )+(B_3 λ^2)/(λ^2-C_3 ). Participants emphasize the importance of understanding dispersion as a derivative of refractive index, suggesting that both first and second order dispersion can be derived using derivatives and the chain rule. The conversation highlights the flexibility in using group velocity dispersion (GVD) as an alternative to GDD.

PREREQUISITES
  • Understanding of the Sellmeier equation and its parameters
  • Knowledge of group delay dispersion (GDD) and group velocity dispersion (GVD)
  • Familiarity with calculus, specifically derivatives and the chain rule
  • Basic concepts of optical materials and their refractive indices
NEXT STEPS
  • Research the application of the Sellmeier equation in optical design
  • Learn how to calculate group delay dispersion (GDD) from refractive index data
  • Explore the differences between group velocity dispersion (GVD) and group delay dispersion (GDD)
  • Study the use of derivatives in optical dispersion calculations
USEFUL FOR

Optical engineers, physicists, and researchers involved in the design and analysis of optical materials and systems, particularly those focused on dispersion characteristics.

Voxynn
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Hi,

I'm trying to take this Sellmeier equation,

n^2 (λ)=1+ (B_1 λ^2)/(λ^2-C_1 )+(B_2 λ^2)/(λ^2-C_2 )+(B_3 λ^2)/(λ^2-C_3 )

for which i have several sets of constants for prospective glasses, and convert it into a group delay dispersion graph, with axes of fs^2 vs wavelength.

How do i rearrange the equation above (or convert the resultant graph) into a form i can use to find the GDD for the glasses?

If it's easier, i could use the GVD instead of the GDD.

Thanks!

Voxynn
 

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Science news on Phys.org
Dispersion is generally some type of a derivative of refractive index. Sometimes people are interested in first order, or second order dispersion, and it's possible to have different definitions for each type (i.e. first or second derivatives with respect to either wavelength or frequency). Just take your definition of dispersion (in equation form) and apply it using derivatives and the chain rule if necessary.
 

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