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Science Technology

First Silicon Laser 122

Posted by ScuttleMonkey from the shiny-happy-scientists dept.
An anonymous reader writes "Since the creation of the first working laser, scientists have fashioned them from substances ranging from neon to sapphire. Silicon was not considered a candidate, because its structure wouldn't allow for the proper line-up of electrons needed to get this semiconductor to emit light. That has now changed thanks to three researchers at Brown University who have created the first directly pumped silicon laser by drilling billions of holes in a small bit of silicon using a nanoscale template."
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First Silicon Laser More

First Silicon Laser

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  • Yeah! (Score:2, Funny)

    by ackthpt ( 218170 ) *
    three researchers at Brown University who have created the first directly pumped silicon laser by drilling billions of holes in a small bit of silicon using a nanoscale template."

    Finally, a laser to fit Dwarf Sharks [sciencenews.org]!

    next up, an army of Barbie fem-bots!

  • Do you hear that? (Score:5, Funny)

    by chriswaclawik ( 859112 ) on Monday November 21, 2005 @06:44PM (#14086360)
    That's the sound of a thousand slashdotters trying to make a "shark with friggin laser beams" joke before I do.

  • Full Text: Site kinda slow already. (Score:5, Informative)

    by Erik_the_Awful ( 675368 ) on Monday November 21, 2005 @06:46PM (#14086379) Journal
    Brown Team Creates 'Impossible' Silicon Laser
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    PROVIDENCE, R.I., Nov. 21 -- Silicon has made its way into everything from computers to cameras. But a silicon laser? Physically impossible -- until now. A Brown University research team led by Jimmy Xu has engineered the first directly pumped silicon laser by changing the structure of the silicon crystal through a novel nanoscale technique.

    Since the creation of the first working laser -- a ruby model made in 1960 -- scientists have fashioned these light sources from substances from neon to sapphire. Silicon, however, was not considered a candidate. Its structure would not allow for the proper line-up of electrons needed to get this semiconductor to emit light.

    Now a trio of Brown University researchers, led by engineering and physics professor Jimmy Xu, has made the impossible possible. The team has created the first directly pumped silicon laser. They did it by changing the atomic structure of silicon itself. This was accomplished by drilling billions of holes in a small bit of silicon using a nanoscale template. The result: weak but true laser light. Results are published in an advanced online edition of Nature Materials.

    The feat is an apt one for Xu, whose Laboratory of Emerging Technologies is also known as the "laboratory of impossible technologies."

    "There is fun in defying conventional wisdom," said Xu, "and this work definitely goes against conventional wisdom -- including my own."

    For now, though, the possible isn't practical. In order to make his silicon laser commercially viable, Xu said, it must be engineered to be more powerful and to operate at room temperature. (Right now, it works at 200 C below zero.) But a material with the electronic properties of silicon and the optic properties of a laser could be useful in both the electronics and communications industries by helping to make faster, more powerful computers or fiber optic networks.

    Xu said that when lasers were invented, they were considered a solution looking for a problem. Now lasers are used to power CD players and barcode scanners, and they can cut everything from slabs of steel to delicate eye tissue during corrective surgery.

    "A very new discovery in science eventually finds an application," Xu said. "t will just take years of work to develop the technology."

    Light emission from silicon was considered unattainable because of silicon's crystal structure, and electrons necessary for laser action are generated too far away from their "mates." Bridging the distance to make the atomic connection would require just the right "matchmaker" phonon arriving at precisely the right place and time.

    In the past, scientists have chemically altered silicon or smashed it into dust-like particles to generate light emission. But more light was naturally lost than created. So Xu and his team tried a new way to tackle the problem. They changed silicon's structure by removing atoms.

    This was accomplished by drilling holes in the material. To get the job done, the team created a template, or "mask," of anodized aluminum. About a millimeter square, the mask features billions of tiny holes, all uniformly sized and exactly ordered. Placed over a bit of silicon then bombarded with an ion beam, the mask served as a sort of stencil, punching out precise holes and removing atoms in the process. The silicon atoms then subtly rearranged themselves near the holes to allow for light emission.

    The new silicon was tested repeatedly over the course of a year to ensure it met the classical criteria of a laser, such as threshold behavior, optical gain, spectral line-width narrowing and self-collimated and focused light emission.

    • Highlights (Score:3, Interesting)

      by TubeSteak ( 669689 )

      Right now, it works at 200 C below zero.

      and

      The new silicon was tested repeatedly over the course of a year to ensure it met the classical criteria of a laser, such as threshold behavior, optical gain, spectral line-width narrowing and self-collimated and focused light emission.

      This is pretty cool stuff & its not something that they just figured out how to do.

      /I'd really like to know how they plan to go from -200C to room temperature.

    • I didn't RTFA, or the posted text, but... wait, what was this about, again?

  • ...but will it be worth it to drill billions of holes into silicon to make lasers? I don't think it will be cost efficient until there are advances made in nanotechnology.
  • Now silicone lazers, I never get a break.

  • After RTFA... (Score:3, Funny)

    by GeneralEmergency ( 240687 ) on Monday November 21, 2005 @06:54PM (#14086443) Journal


    Summary: Stupid Silicon Tricks candidate. No viable application.

    Must be nice to be a Mad Scientist(TM) like "Jimmy" Xu. Nice big lab with all those blinking lights, bendy glassware and stuff.

    • Summary: Stupid Silicon Tricks candidate. No viable application.

      Well, it's going to take a few clever silicon tricks to make optoelectronic devices out of silicon. The linked article alludes to silicon's indirect bandgap, which is why silicon is such a troublesome optoelectronic material. Progress in computing speed and communications bandwidth will stagnate until we either discover how to make optoelectronic devices out of silicon or we discover how to make logic gates out of InGaAsP or AlGaAs. Becaus

  • Which one is first? (Score:5, Interesting)

    by TechyImmigrant ( 175943 ) * on Monday November 21, 2005 @06:54PM (#14086449) Homepage Journal
    Another first silicon laser? So who was really first?

    ----
    http://oemagazine.com/newscast/2004/102604_newscas t01.html [oemagazine.com]

    Los Angeles, CA | 26 October 2004 -- Researchers at UCLA have demonstrated the first silicon laser, which could lead to more effective biochemical detection, secure communications, and defense against heat-seeking missiles.

    ----
    http://www.intel.com/technology/silicon/sp/ [intel.com]

    First Continuous Silicon Laser

    In a paper published February 17, 2005 by the prestigious scientific journal Nature, Intel researchers disclosed the development of the first continuous wave all-silicon laser using a physical property called the Raman Effect. They built the experimental device using Intel's existing standard CMOS high-volume manufacturing processes. This is the third silicon photonics paper Intel has published in Nature since 2004, beginning with the modulator breakthrough (see the Learn More section).

    ----
    http://www.photonics.com/readart.asp?url=readartic le&artid=325&bhsh=1050&bhsw=1680&bhqs=1 [photonics.com]

    PROVIDENCE, R.I., Nov. 21 -- Silicon has made its way into everything from computers to cameras. But a silicon laser? Physically impossible -- until now. A Brown University research team led by Jimmy Xu has engineered the first directly pumped silicon laser by changing the structure of the silicon crystal through a novel nanoscale technique.

    • Re:Which one is first? (Score:2, Informative)

      by Anonymous Coward
      Both the UCLA and Intel lasers were Raman lasers. Note that Intel was careful to claim only the first "continuous" all silicon raman laser so both are technically "first" reports. The excited state in this laser is a defect state related to an electron trapping vacancy and so the authors can claim another first. Unfortunately the trap is fairly shallow, so room temperature operation is probably not going to be possible.

      Note that all of these lasers require optical pumping by another laser and so have no rea

    • Re:Which one is first? (Score:5, Informative)

      by Hal-9001 ( 43188 ) on Monday November 21, 2005 @07:52PM (#14086880) Homepage Journal
      • The UCLA laser was a Raman laser that could only operate in pulsed mode. The Raman effect is a nonlinear effect that requires several external laser beams to power the silicon device.
      • The Intel laser was also a Raman laser and was the first silicon Raman laser that could operate in continuous-wave (non-pulsed) mode.
      • The Brown laser is not a Raman laser. Therefore it only requires a single external laser beam to power the device.

      The holy grail, of course, is an electrically-pumped silicon laser where you apply a voltage directly across the device and get laser light out. We're not there yet, but each of these devices represents progress toward that goal. In particular, a device with direct optical pumping like the Brown laser suggests that direct electrical pumping might not be far off.
      • Stupid question - but what is a laser diode ? Granted it is doped silicon, but why should we care ?

        • Re:Which one is first? (Score:3, Informative)

          by Hal-9001 ( 43188 )

          Stupid question - but what is a laser diode ? Granted it is doped silicon, but why should we care ?

          Actually, most laser diodes are made of aluminum gallium arsenide (AlGaAs) or indium gallium arsenide phospide (InGaAsP). At the moment, there are no commercial silicon laser diodes because there are no silicon laser diodes. The reason, as is alluded to in the linked article, is that silicon is an indirect bandgap material, so a photon (a quantum of light or electromagnetic vibration) emission event can on

        • diodes don't have to be made out of silicon!!

          diodes constructed in different ways out of different semiconductors can have very different properties

      • MMmmmh... Ramen Laser... beef flavored...
    • It's debatable whether the Raman effect is *real* science or not, but in addition to lasers, it can also be used to make mountains, trees, and midgets.

  • So many impossible things done! (Score:5, Funny)

    by Datamonstar ( 845886 ) on Monday November 21, 2005 @06:55PM (#14086451)
    First bubbles, now Lasers! Frikin' Lasers!

  • Next up... (Score:1, Funny)

    by Anonymous Coward
    glowing laser boobies!

  • What about diode lasers? (Score:5, Informative)

    by dsci ( 658278 ) on Monday November 21, 2005 @06:56PM (#14086467) Homepage
    But a silicon laser? Physically impossible

    Diode lasers use silicon, or at least compounds of silicon. Some details here [photonics.com] and here [fsu.edu].

    Pretty cool, though that this is the "the first directly pumped silicon laser."

    • Diode lasers use silicon, or at least compounds of silicon.

      Actually, the first article you cite only mentions silicon carbide as a substrate, that is, what to grow the active material on (gallium nitride in this case); silicon is not involved in the laser emission. The second article is a bit misleading, in that it mentions silicon to illustrate what a semiconductor is, without insisting on the fact that silicon is not a good light emitter due to its indirect bandgap.

      At least, that is, under normal

    • Diode lasers use silicon, or at least compounds of silicon.

      They don't, unless you are willing to call the laser diode in your CD player a "plastic laser" because it's mounting in a plastic casing. The semiconductor in light emitting diodes is usually GaAs and never silicon, mainly because silicon diodes just won't emit light (no even infrared).

  • Intel already did this (Score:3, Interesting)

    by warrior ( 15708 ) on Monday November 21, 2005 @06:58PM (#14086479) Homepage
    And they did it using ordinary semiconductor manufacturing methods. It was in spectrum a couple months ago, you can find it here: http://www.spectrum.ieee.org/print/1915 [ieee.org] They're planning it for use in single-chip optical networking solutions.
  • they should start working on a silicone laser.

    You know...to make bigger boobies.

  • I'm confused. Do we mean this laser [dodgeballmovie.com]

    or thislaser? [imdb.com]

  • Unfortunately... (Score:4, Funny)

    by Anonymous Coward on Monday November 21, 2005 @07:17PM (#14086598)
    From TFA...
    "Right now, it works at 200 C below zero."

    It looks like we'll be seeing penguins with laser beams long before sharks with lasers beams.

  • Porous Silicon (Score:2, Interesting)

    by karvind ( 833059 )
    Is this too much different from photoluminesence from porous silicon [uni-kiel.de] ? That was shown in 90s and yes it wasn't coherent.
    • Yes, it is different, and no it may not be. The difference is, as they state in the article:

      The new silicon was tested repeatedly over the course of a year to ensure it met the classical criteria of a laser, such as threshold behavior, optical gain, spectral line-width narrowing and self-collimated and focused light emission.

      These are characteristics for stimulated (the "s" in laser) emission, not spontenous emission, which is what you had in the previous photoluminesence work.

      However, it may not actually
  • "Always keep your optics clean."
    • Kent: My condolences on your meltdown.
      Chris Knight: What meltdown, Kent?
      Kent: I'm not saying you had one, because how would I know? But just in case you do.
      Chris Knight: You slime!
      Kent: It's your own fault, Knight. Didn't anyone tell you to make sure your optics are clean?

      http://imdb.com/title/tt0089886/ [imdb.com]
      "When he gets mad, he doesn't get even... he gets creative"

      Mitch: And from now on, stop playing with yourself.
      Kent: It is God.

  • nanoscale template metaprogramming (Score:4, Funny)

    by smittyoneeach ( 243267 ) * on Monday November 21, 2005 @07:28PM (#14086677) Homepage Journal
    smoke pouring soon out of a C++ compiler near you!
  • Whats the difference between this and the laser diode found in any CD player or laser pointer?? Laser diodes have been around for 30 years.

    • Re:What about laser diodes? (Score:4, Informative)

      by serbanp ( 139486 ) on Monday November 21, 2005 @07:48PM (#14086849)
      The laser diode you're talking about is not made of silicon...
    • What's different about it is that it's made out of the exact same stuff that your CPU is made of. So you could make a CPU with lasers on the die , reducing complexity and increasing compactness and integration. It's not that they're better lasers, it's that it opens the door to do more stuff with optical computing, networking, etc, ON CHIP. It's a real PITA to try to, e.g., combine GaAs lasers with a Si IC.

      Will it make it possible for your computer to have sex with you tomorrow? No. But it's important n
  • I'm not 100% on this, but I do believe this stuff has been out for a while. In the lab I worked in last summer, we experimented with trying to grow gallium arsenide nano wires on a silicon nanoporous sub strait. This stuff costs us about $100 US for a sliver the size of a nickel. The idea was that we hoped we could get the nano wires to grow strait up and down much more easy than conventional techniques. The experiment failed because the silicon substrait could not be cleaved easily and the temperatures
  • What do they make laser diode chips out of, like the ones in CD players and fiberoptic "lights"?
    • usually gallium arsenide or sometimes gallium nitride.

    • Re:Old Lasers? (Score:4, Informative)

      by kimvette ( 919543 ) on Monday November 21, 2005 @09:45PM (#14087537) Homepage Journal
      When did GaAs or GaAn become equivalent to Si?

      From http://www.mtmi.vu.lt/pfk/funkc_dariniai/diod/led. htm [mtmi.vu.lt]

      he radiative recombination of electron-hole pairs can be used for the generation of electromagnetic radiation by the electric current in a p-n junction. This effect is called electroluminescence. In a forward-biased p-n junction fabricated from a direct band gap material, such as GaAs or GaN, the recombination of the electron-hole pairs injected into the depletion region causes the emission of electromagnetic radiation. Such a device is called a Light Emitting Diode (LED). If mirrors are provided (usually by cleaved crystallographic surfaces of the semiconductor) and the concentration of the electron hole pairs (called the injection level) exceeds some critical value, this device may function as a semiconductor laser that emits a coherent electromagnetic radiation with all photons in phase with each other. LEDs fabricated from different semiconductors cover a broad range of wavelengths, from infrared to ultraviolet.

      The electrical conductivity of a semiconductor can be increased by adding doping elements, or small percentages of impurity elements, to the semiconductor. The presence of the small traces of impurity elements can yield extra charge carriers which are free to move through the material.

      In the compound gallium arsenide, each gallium atom has three electrons in its outermost shell of electrons and each arsenic atom has five. This gives an average of four electrons per atom in the compound. When a trace of an impurity element with two outer electrons, such as zinc, is added to the crystal, the result is the shortage of one electron from one of the pairs. This shortage sets up an imbalance in which there is a place in the crystal for an electron but there is no electron available. This is commonly called a "hole." This forms the so-called p-type semiconductor in which the conduction of electricity is by motion of the hole from one atom to another.

  • Si Laser? (Score:3, Interesting)

    by SHUT_TEH_FACE ( 844019 ) on Monday November 21, 2005 @09:14PM (#14087380)
    This is particularly interesting to me. Not twenty minutes ago, my professor in Laser Theory spent a few minutes describing why Si lasers would never work, and we'd be rich to figure out how to get one to work.

  • xu? (Score:1, Funny)

    by Anonymous Coward
    Xu said. "t will just take years of work to develop the technology."

            Funny, wouldn't have guessed Xu to be a Brit.
    • If Xu was a Brit, he would have said: "We'll work on this for a couple of years, fail to make anything viable, sell the rights to a Far Eastern company for peanuts and watch them make it a commercial success and earn bazillions from it."
  • I guess the Brown research team just wnated to see if they can emit laser light through silica. but man... it's not
    practicle, and it's very ineffecient. Why not focus research on creating something that's extremely effecient?

  • The first silicon laser produced is not very powerful. It is an "A" cup. In three years the Dolly Parton laser should be in full effect.

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