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Asymmetric transmission of Infrared

  1. Oct 17, 2014 #1
    Is it possible to have a material that transmits infrared in one direction but not in the other? There are a few articles available that say it is, though I don't have any here with me now.

    So, lets say you make a hollow sphere of this material, oriented so that infrared light can pass out of the container but not into it. Would that make anything inside of the sphere very cold?

    Edit: removed misleading reference to a "one-way mirror"
     
    Last edited: Oct 17, 2014
  2. jcsd
  3. Oct 17, 2014 #2
    Asymmetric light propagation based on semi-circular photonic crystals
    Wang Lin-Hui et al 2014 Chinese Phys. B 23 034215 doi:10.1088/1674-1056/23/3/034215


    A new structure based on a semi-circular photonic crystal is proposed to achieve asymmetric light propagation. The semi-circular photonic crystal structure proposed in this paper is a deformation of a two-dimensional conventional square photonic crystal. Through the directional bandgap of the semi-circular photonic crystal, the light from one direction can transfer to the other side, but the light from the opposite direction cannot. A high contrast ratio is obtained by designing the constitutive parameters of the photonic crystal and choosing the suitable light frequency. This structure promises a significant potential in optical integration and other areas.
     
  4. Oct 17, 2014 #3
    I can think of several uses in power generation...say a thermoelectric generator with its cold side connected via heat pipe to the inside of the sphere such that the cold side is always kept much lower than ambient temperature. Would this create a sort of perpetual generator? Something tells me no, and I fear I am missing something key here :-(
     
  5. Oct 17, 2014 #4

    Drakkith

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    Perfect one-way mirrors do not exist. Normal one-way mirrors are not actually "one-way", they simply reflect about half of the incident light from either side. To work, you need a darkened room on one side and a well lit room on the other.

    If such perfect one-way mirrors existed, you could create a source of infinite energy, which is not possible.
     
  6. Oct 17, 2014 #5
    I wasn't asking about normal one-way mirrors...please read the article in my second post...
     
  7. Oct 17, 2014 #6

    mfb

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    One-way mirrors and one-way transmission (they are the same idea) do not exist. They would violate the second law of thermodynamics.
    I don't have access to that paper, but I would guess they suggest some active stuff - external energy input to circumvent that. Also note it is a suggestion instead of an experiment and appeared just in some national journal (maybe for a good reason?).
     
  8. Oct 17, 2014 #7
    Asymmetric light propagation in chirped photonic crystal waveguides
    H. Kurt, D. Yilmaz, A. E. Akosman, and E. Ozbay »View Author Affiliations
    Optics Express, Vol. 20, Issue 18, pp. 20635-20646 (2012)

    We report numerical and experimental investigations of asymmetric light propagation in a newly designed photonic structure that is formed by creating a chirped photonic crystal (PC) waveguide. The use of a non-symmetric distribution of unit cells of PC ensures the obtaining of asymmetric light propagation. Properly designing the spatial modulation of a PC waveguide inherently modifies the band structure. That in turn induces asymmetry for the light’s followed path. The investigation of the transmission characteristics of this structure reveals optical diode like transmission behavior. The amount of power collected at the output of the waveguide centerline is different for the forward and backward propagation directions in the designed configuration. The advantageous properties of the proposed approach are the linear optic concept, compact configuration and compatibility with the integrated photonics. These features are expected to hold great potential for implementing practical optical rectifier-type devices.
     
    Last edited: Oct 17, 2014
  9. Oct 17, 2014 #8

    mfb

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    Yes you posted the abstract before, but it does not say how they want to achieve that and that link works for uwo members only.
     
  10. Oct 17, 2014 #9
    That was a second article...sorry for the uwo only link, it has been removed!
     
  11. Oct 18, 2014 #10
    Here's a link to a NIST news article: http://www.nist.gov/cnst/light-070114.cfm

    "Testing their structures, the researchers found that around 30 times more light passed through in the forward direction than in reverse, a contrast larger than any other achieved thus far with visible light."

    This is apparently without any form of energy input, aside from the light itself.
     
  12. Oct 18, 2014 #11

    mfb

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    Ah, the angles are the trick:
    It works well with lasers or other focussed light sources, but not with thermal radiation.
     
  13. Oct 18, 2014 #12

    Drakkith

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    The way I'm reading it is that if the incident light hit at a non-normal angle then it can propagate backwards through the material. Is that correct?
     
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