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Blue-shift due to oblique angle of the incidence

  1. Jun 7, 2007 #1
    I posted this question in another category but no replies, probably this place is more appropriate.

    I read a paper and it states that "the reflection spectrum is blue-shifted due to oblique angles of incidence" without a reference.

    Can any one show me the reference of this phenomenon?

  2. jcsd
  3. Jun 8, 2007 #2


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    Please do not do multiple post. This is clearly prohibited in the PF Guidelines that you have agreed to.

    Secondly, did you notice that you did the exact same bad habit here? You started about a paper that you read, but you never gave the exact citation to it. I've told this to everyone who come here and post something that says "I heard somewhere..." or "I read somewhere...". You must give the exact reference, or all of this could be moot.

    This also is in the wrong forum. I'll move it to where I think it is more appropriate, especially when I have no clue what paper you were reading.

  4. Jun 12, 2007 #3

    Claude Bile

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    The reflection spectrum of what? Give us some context and we may be able to help.

  5. Jun 12, 2007 #4
    I'm quite sorry for that. I'm reading to understand the Second Harmonic Generation. The article I read (in our language, not English. I do not know the reference either) quoted the statement somewhere. That's why I ask you for the reference for the phenomenon since I think it's a popular effect that I don't know.

    After finding I have found the citation of the English article with that statement:


    The original paper does not have the reference about this phenomenon either (the last page).

    I just wonder why the wavelength of the light can change due to the oblique incidence. A bit weird to me.
  6. Jun 19, 2007 #5

    Claude Bile

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    The article does not mention the shift of the reflection spectrum per-se, only a shift in the band-edge of a Photonic Band Gap. In fact, in the context of the article it sounds like a bit of a throw-away comment - I see this all the time in these papers where the measured reflection peak does not correspond to the predicted peak; very little discussion is usually devoted to discrepancies between measured and predicted values!

    The shift of a band-edge toward the blue-end of the spectrum due to an increase in angular incidence is not an intuitive or obvious result in my opinion, and in the context of the paper, this effect probably warranted some more discussion. What exactly causes it? Well that's hard to say without knowing details of the dispersion relation and the photonic crystal structure to start with.

    The real question I believe is whether this effect is common to most or all photonic crystals, or is this effect specific to this particular crystal? Unfortunately I am not well-read on this subject, so I can't answer this question with confidence - have you encountered this effect in other papers?

  7. Jun 22, 2007 #6
    Thank you, Claude, for the comment. In fact, this is the first time I saw such statement. I even asked the one who works in photonic crystals and no explanation at all. Now I believe this is not a universal effect like, for e.g., a Newton law, otherwise people would know that.
  8. Jun 24, 2007 #7

    Claude Bile

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    You may want to email the author(s) of the paper if it is something you really want to clear up.

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