Fotonisk krystal

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Fotografi af et fotonisk fiber som pga. ulinearitet ændrer lysets bølgelængde ned langs fiberen.[1]

Fotoniske krystaller er periodiske dielektriske eller metal-dielektriske (nano)strukturer som er designet til at påvirke elektromagnetiske bølgers (EM) udbredelse på den samme måde som det periodiske potential i et halvledende krystal påvirker elektronernes bevægelse ved at definere tilladte og forbudte elektriske energibånd.

Fraværet af tilladte udbredelsesenergibånd indeni strukturen for et interval af bølgelængder kaldes et fotonisk båndgab, som forårsager bemærkelsesværdige optiske fænomener, som bl.a. resulterer i; spontan udsendelse, generering af alle regnbuens farver ud fra infrarødt-lys, højreflekterende spejle som virker i alle retninger og lysleder med lavt tab, og materialer med negativt brydningsindeks.

Fotonisk krystal er grundlæggende set baseret på det fysiske fænomen diffraktion.

Kilder/referencer[redigér | redigér wikikode]

  1. 2004-05-24, Sciencedaily: Tightly Focused Laser Light Generates Nonlinear Effects And Rainbow Of Color Citat: "..."supercontinuum generation in nonlinear fibers." The phenomenon can be observed in a new class of optical fibers, called photonic crystal fibers. PCFs consist of a tiny solid glass core surrounded by a cladding, or casing, that contains air holes along the length of the fiber...As the IR light propagates, or spreads, through a 1-meter-long fiber, the light appears, first orange, then yellow and finally green...The visible lightwaves emerge from the fiber as white light, which contains all the colors of the spectrum..."

Se også[redigér | redigér wikikode]

Eksterne henvisninger[redigér | redigér wikikode]

  • Webarchive backup: Ingeniøren nr. -3/1999: Dansk gennembrud i fiberoptik Danske og engelske forskere har sammen bevist, at optisk fiber med huller i kan transportere lys over lange afstande.
  • Vejviser: Photonic Crystal and Photonic Band Gap Links
  • Cnet, August 31, 2000, Why photonics? Citat: "...Demand for photonic equipment is skyrocketing. Internet traffic on the backbone networks has been doubling every three months and shows no sign of abating. Companies are laying fiber in just about every cross-country right-of-way they can find. First it was along the railways, and now it's the gas pipelines, sewers and just about any conduit you can think of... "
  • November 3, 2000, Sandia LabNews: Cheesecloth-like photonics device bends light with little loss Citat: "...the cheesecloth-like structure can be considered essentially a wire for light...Because of the very small light loss, the technique offers the potential of ultimately replacing electronic chips with faster, cooler photonic chips...two-dimensional crystals are cheaper and far easier to build..."
  • Number 646 #1, July 16, 2003, AIP: Photonic Crystal Shifts Energy Citat: "...Shawn Lin and his Sandia colleagues, in the course of their studies of photonic crystals, have seemed to challenge the venerable formulation, made by Max Planck a hundred years ago, of what kind of emission spectrum a body should have..."
  • CERN Courier: Photonic crystal makes flat lens Citat: "...The key to creating the flat lens lies with the recent advent of materials – photonic crystals – that effectively have a negative index of refraction...the principle could herald a revolution in optics..."
  • BBC News: 3 January, 2001, Sea mouse promises bright future Citat: "...The sea mouse, or Aphrodita, has spines that normally appear deep red in colour. But when light falls on a spine perpendicular to its axis, stripes of different colours appear – strong blues and greens..."The simple structure responsible for this effect is a remarkable example of photonic engineering by a living organism."..."These structures may have application in photonic communications, where there is much interest in fabricating photonic crystal fibres with similar morphology."..."