What are diffraction orders in nano-structures?

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Discussion Overview

The discussion centers around the concept of diffraction orders in nano-structures, particularly in the context of nano-gratings and their implications for imaging devices. Participants explore the nature of these orders, their physical interpretations, and the underlying principles of diffraction and interference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on the nature of diffraction orders, specifically the -1, 0, and +1 orders, and questions if any order is preferred over others.
  • Another participant describes the zero order as the wave passing through without interference, while the -1 and +1 orders represent interference peaks at one wavelength away, assuming a linear grating.
  • A participant expresses a desire for a more physical interpretation of how the wavelength changes at one wavelength away, despite understanding the theoretical aspects and equations involved.
  • Some participants provide verbatim excerpts from Wikipedia regarding the principles of constructive and destructive interference, discussing how path length variations affect wave phases and intensity maxima and minima.
  • One participant questions whether each diffraction order corresponds to a portion of the initial incident light or if different pulses produce different diffraction orders.
  • A later reply clarifies that if the light source is pulsed, each pulse will produce all diffraction peaks, with the number of observed peaks influenced by factors such as grating quality and light source characteristics.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the nature of diffraction orders and their physical interpretations, indicating that the discussion remains unresolved with multiple competing views present.

Contextual Notes

Some participants reference external sources and papers, but there is a lack of consensus on the interpretation of diffraction orders and their relation to the properties of the light source.

Who May Find This Useful

Readers interested in the principles of diffraction, nano-structures, imaging devices, and the underlying physics of wave interference may find this discussion relevant.

faryafada
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Can someone please describe the diffraction orders on a nano-grating?

I am reading articles about imaging devices, and I cannot understand the diffraction orders

For example, incident wave can be mapped into a propagating wave through the -1, 0, and+1 diffraction orders.

Is any of these orders preferred over others? What is their difference?
 
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Zero order is the wave passing through without interference. The -1 and 1 are the interference peaks on either side at one wavelength away. Assuming a linear grating
 
Hyo X said:
Zero order is the wave passing through without interference. The -1 and 1 are the interference peaks on either side at one wavelength away. Assuming a linear grating

I know the theory, also the equation for k'= k+ n 2 pi/period, n being the diffraction order. I want a more physical interpretation. How is it possible that the wavelength is changed when you say at one wavelength away?
 
verbatim http://en.wikipedia.org/wiki/Diffraction_grating

"Since the path length varies, generally, so will the phases of the waves at that point from each of the slits, and thus will add or subtract from one another to create peaks and valleys, through the phenomenon of additive and destructive interference. When the path difference between the light from adjacent slits is equal to half the wavelength, λ/2, the waves will all be out of phase, and thus will cancel each other to create points of minimum intensity. Similarly, when the path difference is λ, the phases will add together and maxima will occur. "

if this is problematic you can revisit constructive or destructive interference, or the wave-particle duality and the double-slit experiment.
 
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Hyo X said:
verbatim http://en.wikipedia.org/wiki/Diffraction_grating

"Since the path length varies, generally, so will the phases of the waves at that point from each of the slits, and thus will add or subtract from one another to create peaks and valleys, through the phenomenon of additive and destructive interference. When the path difference between the light from adjacent slits is equal to half the wavelength, λ/2, the waves will all be out of phase, and thus will cancel each other to create points of minimum intensity. Similarly, when the path difference is λ, the phases will add together and maxima will occur. "

if this is problematic you can revisit constructive or destructive interference, or the wave-particle duality and the double-slit experiment.
I've been reading articles about this consistently during these two days, I have no problem with constructive/destructive interference.
I have another question now, is every diffraction order a portion of the initial incident light being propagated within the medium to produce other diffraction orders or different pulses produce different diffraction orders?
 
Do you have a reference to the paper you are reading or the source you're trying to understand?

By pulses, I assume you mean the light source is not continuous: it is an on/off/on/off/on/off blinking light source, like a laser with a chopper in front of it. Each pulse is identical and indistinguishable from each other pulse. In a standard diffraction grating, each pulse will produce all of the diffraction peaks. -n, ... -1, 0, 1, ... n.
Physically, How many peaks are observed (the number n) is determined by the quality/uniformity of the grating, the intensity and collimated -ness of the light source, and the sensitivity of the detector.
 
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