Connect with us

Photonics? / frequency multiplier,

Discussion in 'Electronic Design' started by Ken S. Tucker, Mar 11, 2012.

Scroll to continue with content
  1. Suppose one views a photonic (ElectroMagnetic Radiation) image,
    I'm thinking in the microwave range. Can said images frequency
    be multiplied, such as frequency x multiplier = Frequency
    up to a visual range?

    The application might be interesting to read.
    Astronomers have found that as distance of an objects image
    increases, the light from said object is "Red Shifted".
    That effect creates a kind of *Information Barrier* at
    ~14 Giga Light years (14GLy), as the EMR is shifted to what
    appears as the CMBR (Cosmic Microwave Background Radiation).

    The effect is arguably a Doppler Shifting or a General Relativistic
    effect, either takes an emission Frequency and divides it as
    Frequency / multiplier = frequency.

    If photonic multiplication can restore frequency to Frequency,
    then we might be able to image beyond the Information Barrier.
    Regards
    Ken S. Tucker
     
  2. Tim Williams

    Tim Williams Guest

    Be interesting to make, perhaps a metamaterial, which doubles or multiplies
    the frequency of fields in space. A lens or dish could be made out of this
    material, to transmit or reflect light generated by the interaction with
    incident radio waves, perhaps THz radiation. Bias could be incorporated to
    provide amplification; this would be the bulk equivalent of the
    zero-dimensional frequency tripler (which distorts the original signal,
    producing 2nd harmonic, which gets implicitly mixed with the original,
    making a fairly linear tripler).

    Such material can probably be fabricated today from layers of SiO2,
    amorphous silicon and aluminum interconnects -- amorphous transistors suck,
    but it would be an interesting proof-of-concept that might work into the
    GHz. I don't know if schottky diodes can be made with any performance with
    amorphous silicon, but regular MOS structures should still do fine. Good
    enough for TFTs.

    Can Al2O3 be grown by epitaxy on Si? I know the opposite way works.
    Annealing probably isn't possible; growth from solution (Al2O3 is soluble in
    Na3AlF6 and similar salt 'alloys') is probably necessary. Hmm, making
    reliable MOS gates after soaking in a sodium ion bath would be...
    interesting?

    Tim
     
  3. The 'edge', if there is one, seems to be found by linearly
    extrapolating the recession velocity described by Hubble's
    constant to where it reaches c. That's just silly.

    There is no need to have EM energy in the visible range to
    make images, either. We can make images using infrared and
    radio waves just fine. Of course, we need huge apertures
    to get interesting resolution, but that's needed for raw
    sensitivity too, anyway.

    Jeroen Belleman
     
  4. It's the other way around, actually: Remote objects have
    their observed spectra increasingly red-shifted, which is
    explained by positing they are moving away.

    One problem with this is that when you extrapolate that
    sufficiently far backwards, you end up with something
    that present-day physics cannot explain.

    Then again, there are quite a few things in the universe
    that present-day physics has trouble with, and most
    'explanations' are merely unbridled fantasy.

    Jeroen Belleman
     
  5. In cosmology, like religion, I agree with everybody else,
    the model is your choice.

    A standard telescope can increase the brightness, which is
    actually increasing the Number of photons in an image.

    Total Energy = Number x (Plancks h) x frequency

    My curiosity is to boost the Total Energy by

    Total Energy = Number x (Plancks h) x Frequency

    where Frequency = frequency x multiplier.

    Not quite the same as 'heterodyning' or a photo multiplier,
    which increases Number.
    Regards
    Ken
     
  6. Guest

    At sufficient power densities, some materials will behave in a
    non-linear way and produce sum and difference frequencies. Even a
    "transparent" fiber might do this at sufficient (close to melting)
    power levels.

    Of course, this is unusable for image generation purposes, in which
    the power levels are _far_ too low.
     
  7. I'll ask you, what if we can see more of the universe, perhaps
    out to 15GLys, what would that mean?

    The 'device' theorized, would have applications to earthly
    photonics, (cosmology was just an example).
    Ken
     
  8. Well allow me to be incremental, and start with Doppler Shifted Audio.
    Of course we've all experienced that.
    One has a spectrum of audio ranging from 0-10Khz, and then simulates
    approaching that source to Doppler shift to 0-20Khz, linearly, so that
    would be frequency x2, and one can select x3 x4 ...
    Off hand, I haven't done that using either analog or digital computer,
    so that's where I'd need to start.
    Regards
    Ken
     
  9. Martin Brown

    Martin Brown Guest

    Not quite. We actually see back to the surface of last scattering where
    the universe first became transparent to electromagnetic radiation which
    corresponds to the inevitable 4K background radiation noise in radio and
    microwave receiver electronics that will not go away.

    The patterns in that region reflect the tiny perturbations from perfect
    uniformity that will eventually lead to the formation of stars, galaxies
    and clusters of galaxies.

    The surface of last scattering is still well before the position where
    our observable part of the universe runs out. And you do have to be very
    careful how you define the horizon of our universe too...
    Yet another thing that John doesn't understand so it must be wrong.
    You can make very good aperture synthesis images at radio wavelengths.
    All it takes is a load of dishes and some very low noise front ends,
    phase compensators, correlators and associated electronics. Aperture
    synthesis has been done down to tens of MHz. The VLA surveyed ground is
    currently retrofitted to do aperture synthesis at 74MHz see for example.

    http://lwa.nrl.navy.mil/VLSS/

    The tricky bit is in compensating for the atmospheric and ionospheric
    distortions in these low frequency wavebands. Resolution isn't exactly
    great at 4m wavelength even with a 27km baseline.

    The most interesting detectors in astronomy at the moment are in the
    largely unexplored terahertz band. I have seen some preliminary results.
     
  10. I don't understand it either. It has too many ad-hoc patches.
    What would an infinitely deep background of red-shifted galaxies
    at the observed average density look like? Any chance it might
    look like a uniform 3K background? Like Olbers thought it should,
    but after correction by Hubble or Lemaitre and Einstein?

    Jeroen Belleman
     
  11. Martin Brown

    Martin Brown Guest

    Why do you think that? It has good observation evidence that actually
    found a theoretical prediction of the model much to Penzias & Wilsons
    surprise. They spent a lot of time removing pigeon droppings from their
    feed horn (dielectric material as they referred to it in their paper)
    before concluding that the noise really was uniform and from the sky.

    It also neatly explains the relative cosmic abundances of the elements.

    The only ad hoc patch that I can see is the Guth's inflation hypothesis
    which is required to make the universe sufficiently uniform.

    You might find Martin Rees book "Just 6 Numbers" interesting.
    No. Nothing like right. Tired light theories are completely discredited
    and you would then have to figure out some way through the what happened
    14bn years ago when based on our observations everything was pretty much
    in the same place. And light from further away than 14bn light years
    hasn't had time to reach us yet so an infinite universe cannot help you
    unless it has also been there for infinite time as well.

    One of the fatal nails in the coffin of steady state theories in the
    1960's was the discovery that looking at the early universe in radio
    wavelengths found far more very bright radio sources the deeper they
    looked. The early universe was a much more exciting and dangerous place
    to be with a lot more going on. It is quite benign near us now.
     
  12. Martin Brown

    Martin Brown Guest

    Typical that you quote the whole thing to add your trivial tag line.

    I won't bother because I don't think you have the wit to understand.
    However, for the benefit of other interested readers I will refer you to
    the DAMPT website which explains the four observational pillars of the
    hot big bang cosmology without any detailed mathematics.

    http://www.damtp.cam.ac.uk/research/gr/public/bb_home.html

    It always loses something put into words and without the mathematics.

    We actually live in a golden era of observational cosmology where new
    instruments can now survey and image the sky at high resolution in
    wavelengths ranging from X-rays down to long wave radio. Even the gaps
    like terahertz are now being filled in by metamaterial based sensors.

    Theoretical models are now very well constrained by the observational
    data. When I was a student you could still hide "cold dark matter" as
    old biros, chair legs and sticks of rhubarb - but not any more.
     
  13. Martin Brown

    Martin Brown Guest

    Perhaps you would like to share with the rest of us your great insight
    that tells you that Big Bang Cosmology is incorrect?
    Of course not. The universe has only been around for at most 14bn years
    so looking for 30bn year galaxies would be like digging a big pit on the
    Earth to look for 10bn year old fossils (Earth is 4.5bn years old).

    Radio telescopes are now down to deciding what new experiments will help
    distinguish between the various competing theories by finding additional
    observational constraints. Deep radio surveys at ever lower frequencies
    and longer baselines have been done to death already.

    The answer is already known the "Steady State Universe" is dead and had
    curled up its toes in the late 1960's though it took a while for its
    main proponents to accept this and/or die off. The battle royal between
    Hoyle vs Ryle (radio astronomy) in Cambridge was particularly brutal.

    Observational data from the most distant regions of the universe are
    limited to objects that are intrinsically *very* bright and/or imaged
    for us by gravitational lensing of an intervening galactic cluster.

    http://www.sdss.org/news/releases/20031217.lensing.html

    And in case you are wondering how they know the views are images of the
    same quasar there are two pieces of evidence. Spectroscopy and temporal
    variations in light output. It is an annoying property of quasars that
    their output varies rather rapidly (also implying small physical size
    and/or relativistic beaming).

    The furthest back a galaxy or quasar has been seen is about Z=8 and one
    or two really bright ones have been found suitable for further study.

    http://www.eso.org/public/news/eso1122/
     
  14. People sometimes pontificate as tho they have god on speed dial,
    ((I've never received a call from Marty ;-)).
    10 GLys away are galaxies requiring 10 Gigayears to form, setting back
    it's early formation to 20G years ago....hmmm....
    so Big Bangers (BBs) merely modify (speed up) galactic evolution.
    OTOH GRists (General Relativity specialists), can provide the same
    observations using an *infinite universe* model.
    BBs sell more books, and pop-sci, so that's in it's favor.
    Regards
    Ken
     
  15. John S

    John S Guest

    You're getting help on these replies from your wife, I think.
     
  16. Tim Williams

    Tim Williams Guest

    Gauss must be rolling in his grave...

    Tim
     
  17. Les Cargill

    Les Cargill Guest

    So what's holding it back, then? In a soap bubble, it's
    the shear in density between the air and the soap. I'm
    thinking it's electrostatically maintained. Why
    is there an edge to a bubble in the dense soup? The radii
    of attractio/repulsion seem off.

    I do like the poetry of the image of a child blowing a bubble,
    and that bubble is our universe. That's way cool.
    So think relativistically; the timebase
    is different at the edges than it is in the middle.

    I think I read that somewhere, can't remember. But in relativity,
    time is not an independent variable.
    I like the origin myths of aboriginal peoples better. They've
    had longer to polish them.
     
  18. Martin Brown

    Martin Brown Guest

    You are still thinking in semi-classical terms of there being something
    outside our universe. That is not required at all although it is not
    excluded as a possibility in modern cosmology.
    I think you will find a gentleman by the name of Gauss proved a long
    time ago that inside a uniform spherical shell of mass or charge you
    will feel no attractive force from it at all.
    Not true. Dark matter was proposed by Oort in 1932 to explain the
    anamolous motion of stars in the Milky Way. That is nearly 3 decades
    before the huge fight over Big Bang vs Steady State in the 1960's.

    Dark matter was proposed to explain why galaxies don't fly apart. If you
    look at the speed the stars and gas in the spiral arms are doing and yet
    they are held together by gravity. The initial idea was that there was
    dark matter that is non-luminous in the form of rocks and dust to make
    up the balance. Modern observational techniques are now sensitive enough
    to rule that out so cold dark matter has to be some form of mass that
    doesn't interact in other ways with ordinary matter or with
    electromagnetic radiation.

    It is reassuring that ab initio computer simulations of CDM universes
    now produce very good agreement with the observations of the microwave
    background, elemental abundances and galaxy cluster formation that we
    observe.

    Dark energy is actually the name that has been given to the constant of
    integration that Einstein inserted into his field equations to
    facilitate a steady state universe solution. Without it he had proved
    that universes had to either expand or contract. It is ironic that it
    seems now from observations that the value is not quite exactly zero
    although its influence only really makes a difference at very great
    distances.
     
  19. josephkk

    josephkk Guest

    Actually that is done in music, with a DSP, even in realtime for karaoke.
    As for whether the techniques are relevant to your use is rather
    questionable.Actually Al2O3 is much more readily soluable/etchable than Si. What would
    be really cool is SOI processes on BN.

    ?-)
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-