Pulsed cooperative backward emissions from non-degenerate atomic transitions in sodium
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| Number of Parts | 49 | |
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| License | CC Attribution 3.0 Unported: You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
| Identifiers | 10.5446/38733 (DOI) | |
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Emission nebulaElectric power distributionParticle physicsPlain bearingVideoComputer animation
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AstronomerLaserLightMeasurementSkyNightStellar atmosphereAtmosphärische TurbulenzAdaptive opticsStarReference workGuide starDistortionLaserMeeting/Interview
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Direct currentLaserLightAtomismStellar atmosphereDistortionLaserGuide starGround (electricity)Signal (electrical engineering)PaperAtom laser
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LaserCarburetorAngeregter ZustandAtomismEmissionsvermögenDensityDirect currentSpeckle imaging
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Intensity (physics)Vertical integrationPower (physics)Airbus A300Fiat 500 (2007)Electronic componentDirect currentPower (physics)TheodoliteWavelengthEmissionsvermögenSpare partComputer animationDiagram
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PaperAngeregter ZustandMeeting/Interview
Transcript: English(auto-generated)
00:04
As researchers from the Institute of Quantum Science and Engineering at Texas A&M University, it's one of our dreams to create laser-like light in the sky directed back towards us. There are various ways that technology like this could be beneficial. An example of such would be with laser guide star technology.
00:23
As astronomers observe the night sky, turbulence in the atmosphere makes it hard to make very precise measurements. Adaptive optics allows a technique to correct for these distortions. However, they need a reference star. A bright star in the sky can be used as a reference, but a bright star is not always where they want it to be or need it to be.
00:50
This is where artificial laser guide star technology comes in handy because they can, in a way, create their own star in the sky.
01:00
An artificial guide star is created by directing a laser beam into the sodium layer of the atmosphere. The laser light excites the sodium atoms and causes them to glow. On the ground, the light from this glow is collected and used for atmospheric distortion correction. Now the glow is in all directions.
01:21
This means some energy is lost in directions that we don't observe. What if, instead, we could create a laser guide star that was in the backwards direction and not off to the sides? This could mean a better signal, a better laser guide star. This is one of the motivations for our research.
01:44
In our paper, we discuss an experiment we have done in our labs here at Texas A&M University. We use ultra-fast laser pulses to excite sodium atoms in a dense sodium vapor via two-photon absorption. A cooperative emission at 1140 nanometers is observed in the backward direction.
02:04
An ultra-fast street camera is used to measure the temporal characteristics of this emission. We observed that as the power of the input pulse increases, the relative delay of the emission decreases. We also saw that for high enough input power, there are two temporally resolved pulses emitted in the backward direction.
02:26
Our analysis shows that these two pulses come from two non-degenerate atomic transitions in the sodium. This means that we get not one, but two emissions with slightly different wavelength components in the backward direction.
02:42
We have really enjoyed doing this research, and we hope you enjoy reading about it. Please take a look at our paper. Thank you.