'Dark Pulse Laser' Produces Bursts of ... Almost Nothing


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In an advance that sounds almost Zen, researchers at the National Institute of Standards and Technology (NIST) and JILA, a joint institute of NIST and the University of Colorado at Boulder, have demonstrated a new type of pulsed laser that excels at not producing light. The new device generates sustained streams of "dark pulses" -- repeated dips in light intensity -- which is the opposite of the bright bursts in a typical pulsed laser.

Despite its ominous name, the dark pulse laser is envisioned as a tool for benign communications and measurements based on infrared light frequencies. The laser's ultrashort pulses span just 90 picoseconds (trillionths of a second), making the device suitable for measurements on short timescales. Dark pulses might be useful in signal processing because, unlike bright pulses, they generally propagate without distortion. Dark pulses might be used like a camera shutter for a continuous light beam in optical networks.

Described in Optics Express, the new NIST/JILA technology is the first to generate dark pulses directly from a semiconductor laser cavity, without electrical or optical shaping of pulses after they are produced. The chip-sized infrared laser generates light from millions of quantum dots (qdots), nanostructured semiconductor materials grown at NIST. Quantum dot lasers are known for unusual behavior.

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Perhaps it could be a new feature in high end cameras?

I don't think you quite understood what they meant with the shutter analogy :)

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so basically you just keep turning it off and boom, you have yourself a dark pulse laser? awesome.

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It's a Laser that essentially "removes" light, kind of a negative light. as opposed to a positive light.

I would like a more detailed explanation of how it removes light....i'm guessing since it is not generating its own light its removing light from outside sources? how in the hell is that possible? I was under the impression the only thing that could effect a visible light source like that was immense amounts of gravitational force.

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They built a laser that emits regular intervals of significantly reduced light intensity and they use those "dark" pulses for timing or something to that extent.

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I would like a more detailed explanation of how it removes light....i'm guessing since it is not generating its own light its removing light from outside sources? how in the hell is that possible? I was under the impression the only thing that could effect a visible light source like that was immense amounts of gravitational force.

Hi!

THIS is an interesting work on dark pulse. However, it is not that original as it said. Physical Review A, 80, 045803 (2009) reported the emission of dark pulse in fiber lasers laser year. THE cavity design is simpler than this one but with all fiber format and many other advantages. If you feel interested, you could see this paper through http://www3.ntu.edu.sg/home2006/zhan0174/pra.pdf. After reading this paper, you will know how this dark structure form. It is just because of the normal dispersion cavity and thus only dark pulse solution was allowed.

PRA.PDF

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Hi!

THIS is an interesting work on dark pulse. However, it is not that original as it said. Physical Review A, 80, 045803 (2009) reported the emission of dark pulse in fiber lasers laser year. THE cavity design is simpler than this one but with all fiber format and many other advantages. If you feel interested, you could see this paper through http://www3.ntu.edu.sg/home2006/zhan0174/pra.pdf. After reading this paper, you will know how this dark structure form. It is just because of the normal dispersion cavity and thus only dark pulse solution was allowed.

Thanks! I will have to read through this.

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ok this does NOT produce negative light as some might imagine

It produces low frequency light- think about a sin wave but it doesn't quite reach -0 but stays confined in the negative space.

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It's a Laser that essentially "removes" light, kind of a negative light. as opposed to a positive light.

Darth Vader will be proud. :shiftyninja:

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