[HN Gopher] Electrons turn piece of wire into laser-like light s...
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Electrons turn piece of wire into laser-like light source
Author : dr_dshiv
Score : 57 points
Date : 2022-11-06 09:27 UTC (13 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| claaams wrote:
| The author did a good job with the hook but I'm still not sold.
| bilsbie wrote:
| Paywall
| [deleted]
| KurvaKing wrote:
| dtgriscom wrote:
| Well, it had an interesting start...
| adrian_b wrote:
| From the description, the device made by the Chinese team is
| for a free-electron laser what a transistor was for an
| amplifying vacuum tube.
|
| A free-electron laser is also a kind of vacuum tube, and one
| that is extremely large and expensive.
|
| The new kind of free-electron laser, uses the free electrons
| from a solid-state metal wire instead of using free electrons
| from vacuum, so it can be much smaller, much cheaper and much
| more reliable, exactly like a solid-state transistor is in
| comparison with a vacuum pentode or triode.
|
| Without access to complete text, it is not known in which
| wavelength range the metal wire can act as a laser and which is
| the energy efficiency.
|
| Nevertheless, it could revolutionize the use of free-electron
| lasers. Such a laser has a much more limited domain of
| applications than a transistor, so it will not have a similar
| impact, even if it is a similar kind of invention.
|
| The traditional free-electron lasers have the advantage that
| they can be designed to produce light of a desired frequency,
| while most other kinds of lasers are constrained to produce
| only certain frequencies from the spectra of various kinds of
| atoms, ions, molecules or solid crystals.
|
| It would be interesting to know if this new kind of free-
| electron laser can also be designed to produce light of any
| desired frequency (within a certain range).
| bilsbie wrote:
| Thanks for the explanation! Could this be used for holograms
| for less money like hobos? What are some other applications?
| Better laser cutters?
| adrian_b wrote:
| After browsing through the full text, thanks to the link
| provided by another poster, the conclusion is that such
| solid-state free-electron lasers might be realizable only
| in the far infrared, at frequencies much lower than those
| of visible light, unlike the vacuum free-electron lasers,
| which can produce even ultraviolet light.
|
| These can still have many useful applications, but
| holograms are not one of them, because their output will
| not be visible.
|
| Laser cutters are also another excluded application,
| because such lasers will have a low electrical energy to
| light energy conversion efficiency. The reason is that
| these solid-state free-electron lasers, like also most
| other laser types except the laser diodes and some of the
| gas lasers, use another laser as their energy source, so
| the efficiencies of the 2 lasers are multiplied. Actually
| the pumping laser needs almost certainly to be pumped
| itself by a laser diode. Therefore the total efficiency
| will be the product of the efficiencies of 3 lasers, so it
| will be low.
|
| More likely applications would be in communications, Lidar,
| imaging through materials that are opaque for visible
| light, chemical analysis, maybe influencing certain
| chemical reactions.
|
| The fact that solid-state free-electron lasers should work
| only in the far infrared is actually expected, because high
| frequencies, like those of visible or ultraviolet light
| require a large energy difference between the energy of the
| electrons before and after emitting the laser light. When
| the electrons are free before and after emission, that
| means that the pumping source must accelerate them,
| providing the energy difference.
|
| In vacuum, a free electron can be accelerated to any
| energy, e.g. up to levels enabling the emission of X-rays
| when the electrons lose the accumulated energy, but in a
| metal a free electron that is accelerated too much will
| either collide with the lattice of atoms, losing the
| energy, or it might even exit the metal and be lost, like
| in the photoemissive electrodes that were used in the
| earliest video cameras.
| mycall wrote:
| Is there a way to shift light frequency outside of the
| laser? That could open up more applications.
| adrian_b wrote:
| There are frequency multipliers, optical mixers and
| optical parametric amplifiers, which can multiply, sum or
| subtract the frequencies of laser beams.
|
| A well known use is in the green laser pointers, which
| contain a frequency doubler and an infrared laser.
|
| However any frequency conversion device increases the
| cost and reduces the energy efficiency.
|
| It is very unlikely that it would ever make sense to
| multiply the frequency of such a laser with enough stages
| to reach visible light, because that would increase the
| cost much above the alternative solutions that exist for
| tunable lasers in the visible range.
| lightedman wrote:
| Dipotassium Phosphate crystals have been used to
| frequency-shift IR to green light for lasers, IIRC. I
| don't know how well they would work for other frequencies
| but doing 1064 to 532nm is workable.
| swayvil wrote:
| Cheap tunable laser. That's HUGE.
|
| There are amazing tricks available then. For one, in tuning
| to the resonant frequencies of whatever. For low-heat cutting
| stuff, 3d video.
| [deleted]
| RobotToaster wrote:
| Full paper is here https://europepmc.org/article/ppr/ppr485152
| sitkack wrote:
| https://web.archive.org/web/20220421175228/https://assets.re...
| westurner wrote:
| "Coherent Surface Plasmon Polariton Amplification via Free
| Electron Pumping" (2022) Ye Tian, Dongdong Zhang, Yushan
| Zeng, Yafeng Bai, Zhongpeng Li, and 1 more
| https://doi.org/10.21203/rs.3.rs-1572967/v1
|
| > Abstract: _Surface plasmonic with its unique confinement of
| light is expected to be a cornerstone for future compact
| radiation sources and integrated photonics devices. The
| energy transfer between light and matter is a defining aspect
| that underlies recent studies on optical surface-wave-
| mediated spontaneous emissions. But coherent stimulated
| emission, being omnipresent in every laser system, remains to
| be realized and revealed in the optical near fields
| unambiguously and dynamically. Here, we present the coherent
| amplification of Terahertz surface plasmon polaritons via
| free electron stimulated emission. We demonstrate the
| evolutionary amplification process with a frequency redshift
| and lasts over 1-mm interaction length. The complementary
| theoretical analysis predicts a 100-order surface wave growth
| when a properly phase-matched electron bunch is used, which
| lays the ground for a stimulated surface wave light source
| and may facilitate capable means for matter manipulation,
| especially in the Terahertz band._
|
| Polariton: https://en.wikipedia.org/wiki/Polariton
|
| Surface plasmon polaritons :
| https://en.wikipedia.org/wiki/Surface_plasmon_polaritons :
|
| > [...] _Application of SPPs enables subwavelength optics in
| microscopy and photolithography beyond the diffraction limit.
| It also enables the first steady-state micro-mechanical
| measurement of a fundamental property of light itself: the
| momentum of a photon in a dielectric medium. Other
| applications are photonic data storage, light generation, and
| bio-photonics.[2][3][4][5]_
| sitkack wrote:
| This looks ripe for some cutting edge table-top physics!
| westurner wrote:
| - Live ~fMRI in surgery (OpenWater,) #TricorderXPrize
|
| - Atomic antenna that listens on all frequencies; with
| bus and disk throughput as the new limits (Rydberg
| Technologies)
|
| - Nonlocal entanglement, laser-induced coherence, QKD,
| passive backscatter wireless,
|
| Exciting work!
| westurner wrote:
| Near-infrared window in biological tissue:
| https://en.wikipedia.org/wiki/Near-
| infrared_window_in_biolog...
|
| NIRS Near-infrared spectroscopy > Applications:
| https://en.wikipedia.org/wiki/Near-
| infrared_spectroscopy#App...
| stevespang wrote:
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