Optical and electrical bandwidth "outside" air

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Discussion Overview

The discussion revolves around the conversion of optical wavelengths to frequency in different media, particularly focusing on the implications of using a medium with a refractive index greater than 1, such as glass (n=1.5), compared to air. Participants explore the necessary modifications to equations related to optical filters, including Fabry-Perot etalons, when light propagates in these media.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the equations for converting wavelengths to frequencies need to be corrected when using a medium with a refractive index greater than 1.
  • Another participant suggests that if the propagation inside the medium is linear, the spectrum of the laser will not be modified.
  • There is a proposal that the Fabry-Perot equation must be modified to account for the dispersion of the medium.
  • Multiple participants inquire about the necessity of correcting the effective index of filters when they are not used in air, indicating a potential complexity in the definition of effective refractive index.
  • One participant emphasizes the importance of checking related references to understand how the equations were derived, hinting at the complexity of the topic.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the necessary modifications to equations when using different media, with some suggesting corrections while others propose that linear propagation may not require changes. The discussion remains unresolved with competing views on the implications for optical filters.

Contextual Notes

Limitations include potential missing assumptions about the linearity of the medium and the specific definitions of effective refractive index in different contexts. The discussion does not resolve whether the equations need to be modified or how the effective index should be treated.

MiddleVision
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My questions is about the conversion of a range of wavelengths in Hz, such as for an optical filter, in a medium different from air. Since the refractive index n is higher than 1, (let's say n=1.5) and than the value of c is almost 2x108 m/s, also the equation in the link below has to be corrected?

https://www.rp-photonics.com/bandwidth.html

When light is propagating in a different medium than air, is it also necessary to modify accordingly the equations for a Fabry-Perot etalon and similar filters?

Thanks a lot!
 
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MiddleVision said:
My questions is about the conversion of a range of wavelengths in Hz, such as for an optical filter, in a medium different from air. Since the refractive index n is higher than 1, (let's say n=1.5) and than the value of c is almost 2x108 m/s, also the equation in the link below has to be corrected?
If the propagation inside the medium is linear, there will be no modification to the spectrum of your laser.
MiddleVision said:
When light is propagating in a different medium than air, is it also necessary to modify accordingly the equations for a Fabry-Perot etalon and similar filters?
Yes, the Fabry-Perot equation must be modified to accommodate the dispersion of the medium.
 
MiddleVision said:
Does the filter effective index in the equation above have to be corrected then when that filter is not used in air?

https://en.wikipedia.org/wiki/Interference_filter
The fact that the index is called effective refractive index instead of refractive index only, most likely means that its value is determined by more than one media. But to be more accurate, I suggest that you check the related reference (ref. [2]) to know how that equation was derived.
 

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