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Technology Science

Breakthrough In Plastic Lasers 54

esocid writes "Conventional electrically-powered laser diodes used in everyday consumer goods like DVD players are currently based on inorganic semiconductor materials such as gallium arsenide, gallium nitride, and related alloys. Plastic laser diodes offer the promise of covering more of the light spectrum than their counterparts, from near ultraviolet to the near infrared. Yet despite over a decade of research worldwide, plastic laser diodes have not yet been demonstrated because there haven't been any plastics that could sustain a large enough current while also supporting the efficient light emission needed to produce a laser beam. Now researchers at Imperial College London, publishing their findings in Nature Materials in April, are studying a plastic related to PFO (polydioctylfluorene), a blue-light emitting material; by making subtle changes in the plastic's chemical structure they have produced a material that transports charges 200 times better than before, while actually increasing its ability to emit light efficiently."
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Breakthrough In Plastic Lasers

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  • Great! (Score:5, Funny)

    by Daimanta ( 1140543 ) on Saturday May 24, 2008 @04:52PM (#23531114) Journal
    Now, all we need is a breakthrough with plastic sharks.
  • How tunable would these emitters be? Are they suitable as general light emitting components, rather than "just" lasers? Would it be possible to create displays where the color of a pixel was actually changed in real time?
    • Re: (Score:2, Informative)

      by Anonymous Coward
      Hmm. You might be able to get away with tuning using some kind of piezo stack, varying the size of the cavity.
      I'm not sure why you'd want to - lasers have a narrowband emission; better would be to find some chemical structures that replicate (in bulk emission properties) the response of the sensors of the eye.
      • Re: (Score:3, Insightful)

        by argent ( 18001 )
        Chromatically accurate displays are not necessarily used for direct use by the human eye. Consider the article a few months back about what it took to get chromatically accurate white light from arrays of LEDs for illuminating pictures in a gallery.
    • by lixee ( 863589 ) on Saturday May 24, 2008 @05:36PM (#23531404)
      They are tunable in the sense that chemists can play around with them in order to change the bandgap (from Lowest Unoccupied Molecular Orbital to Highest Unoccupied Molecular Orbital), thus changing the wavelength produced.

      I don't know what you mean by changing the color "in real time", but it seems to me that you're talking about electrochemical display devices. They're ridiculously simple to build and can cover a wide range of contrasts. Granted, PEDOT:PSS or similar materials can only go from transparent to dark blue (through a lot of shades of blue), and switching time is quite slow, but let's not forget that this field is at its infancy. Hang around, organic electronics might be huge in the medium term.
      • Re: (Score:2, Informative)

        by Anonymous Coward
        No this is not true.
        They are directly tuneable - as a broad gain medium, you can just change the cavity to _tune_ (literally!) the frequency of light produced by varying the modes which can be supported by the cavity.
        The chemistry will vary the range over which you can do this, though polyfluorene already has a nice fat response up in the blue.

        This is exactly the same as an optically pumped dye laser, as often used for research in the 1980s, but these required jets of the nasty stuff getting flung around an
      • Don't you mean Highest Occupied Molecular Orbital?
  • Awsome (Score:4, Funny)

    by Peter_The_Linux_Nerd ( 1292510 ) on Saturday May 24, 2008 @05:06PM (#23531220)
    Cool, the US government has worked out another piece of technology from the Roswell crash.
    • Re: (Score:1, Informative)

      by Anonymous Coward
      No; a Japanese chemical company (Sumitomo) and a British University.
  • by compumike ( 454538 ) on Saturday May 24, 2008 @05:10PM (#23531246) Homepage
    The original article is here here [].

    Something cool is that while traditional semiconductor lasers have an output wavelength that is very much controlled by the bandgap energy of the material, here the laser is substantially tunable by adjusting the plastic's thickness. (Of course, this is just adjusting the energy states too, but it seems more tunable.) From the paper, "Tuning the film thickness (45-160 nm) enabled access to lasing wavelengths across a 45 nm spectral window (434-479 nm)."

    While it's not real-time electrical tuning over that kind of bandwidth, it's still pretty cool. Tunability is especially useful for detectors of various chemicals, and now this is getting into the wavelength range where more biological substances start to have their spectrographic signatures.

    Electronics kits for the digital generation! []
    • Re: (Score:3, Informative)

      by Liz99 ( 1291588 )
      Unfortunately, you have to be a subscriber to have access to the article. I'd be interested in seeing it at some point.
  • by MLCT ( 1148749 ) on Saturday May 24, 2008 @05:20PM (#23531294)
    This is moving in the right direction.

    The holy grail is an electrically pumped organic laser. Varying the co-polymer ratios has improved electron mobilities, but they still have many orders of magnitudes to go before they would get into the likely energy densities required for lasing.

    People are attacking it from multiple ends. Bradley's group have gone at it by taking an efficient light emitter and attempting to improve its pitiful charge mobilities. Others have taken very good charge carrying organic materials, LETs (light emitting transistors) and attempted to improve their pitiful light emission. (paper) []
    • This is moving in the right direction.
      Organic lasers are clearly the correct direction. In time, humanity will finally reach its ultimate goal; that of genetically engineering itself to grow lasers at several strategically chosen body parts. And no, I'm not referring to eye lasers. ;)
  • Did Vader just make the breakthrough he needed to construct the Death Star laser?
  • by brunokummel ( 664267 ) on Saturday May 24, 2008 @06:56PM (#23531942) Journal
    Now my LEGO Gun will be complete!
  • Would they be called 'plasers'?
  • by LM741N ( 258038 ) on Saturday May 24, 2008 @08:10PM (#23532498)
    You know, every bomb has an LED readout that counts down the minutes and seconds. I saw it on TV. Even nukes have them.
  • by naoursla ( 99850 ) on Saturday May 24, 2008 @11:51PM (#23533465) Homepage Journal
    Shortly after earning my bachelors degree from an unnamed college in the Northest, one of my parent's friends took me aside at a party and gave me a recommendation for a successful career. His advice consisted of two words: plastic lasers.

    I didn't listen to him then but I believe him now.

    Also, I slept with his wife.
  • Btw, gallium arsenide and gallium nitride are not alloys; they're inorganic compounds. An alloy is a mixture of two or more metals. There is a fundamental difference. /wisecrack

Doubt isn't the opposite of faith; it is an element of faith. - Paul Tillich, German theologian and historian