Slashdot Mirror
Mastering Light
thyristor writes "'Researchers at MIT document the ultimate control over light: a way to shift the frequency of light beams to any desired colour, with near 100 per cent efficiency. This technology could revolutionise a range of fields, from turning heat into light, or even into prized terahertz rays - which hold great promise for medical imaging. It could also make it possible to focus a wide range of frequencies into a narrow band, make devices such as light bulbs and solar cells more efficient, and help to keep optical telecommunications networks moving.' These are probably the most exciting results in photonics in the last decade."
Well, with such a frequency translator, we can all imagine all the goodies and baddies that can be made with it. One of them is a cloaking devices, efficient power sources, phase weapons...
Imagine changing harmless light from light bulbs into a focused gamma rays or worse !
- Generate low-frequency (LF) pulse travelling into crystal.
- Apply shock wave to turn crystal into frequency shifter.
- Wait until LF pulse is shifted to higher frequency and emitted from crystal.
- Allow time for crystal to relax to original properties by allowing the shock wave to dissipate.
- Repeat for as long as necessary/desired.
Now, this may or may not create any really usable stream of pulses, but I believe that you would be able to shine a (pulsed) red light in and get a (pulsed) blue light out. Whether the pulsing could be controlled sufficiently to prove useful in optical switching or other applications is yet to be shown.As for the number of wavecycles being equal, I wonder if this is already observed. It would make sense (if the number of wavecycles is conserved) that the resulting higher frequency pulse would be shorter in duration than the incoming lower frequency pulse, due to the relation among the speed of light/frequency of light/duration of pulse.
Reading the article it seems that the light frequency is altered for only a short time, the time during which the shock wave passes through the crystal.
So you put through another shock wave and another and another and another...
You will get the same number of peaks and troughs out, but those that have bounced back and forth a bit (and thus got Doppler shifted) will come out later, having travelled further, and shifted. This technique stretches the light pulse.
So, (asciiart time!) you could put in pulses of green and get out continuous red:
S S S S
gggg gggg gggg gggg
rrrrrrrrrrrrrrrrrrrrrrrr
[View it in a fixed-width font, it'll make sense I promise]
Each green pulse g has been stretched by the shockwave sent at each S and turned to red light r, filling the time for pulse + gap.
Justin.
You're only jealous cos the little penguins are talking to me.
Uhm, it wouldn't mess up anything. A 1280*1024 colourdisplay is essentially a 3840*1024 "monochrome"-display (each R,G,B being separate elements). If you wouldn't need separate elements, you'd have a true 3840*1024 colour display, which would be vastly superiour to sub pixel rendering .. :)
it's in my head
IANAP[hysicist], and so I have some questions about this process.
What I know:
So, when light is converted to a higher frequency (shorter wavelength) where does the necessary energy come from? The shockwave? What about when it is converted to a lower frequency (longer wavelength)? Where does the excess energy go? If the conversion really is 100% efficient (I'm a bit skeptical of that claim), then just imagine the solar panels we could have; sucking up all the UV raining down on us and emitting a soft red glow.
Fascinating stuff. I've got to study more optics and electromagnetic physics.