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Laser Clock Generates One Trillion BPS
FunkyELF writes "Professor of optics, electrical and computer engineering and physics Peter Delfyett, Jr., of the School of Optics CREOL, has developed a laser-driven clock that is smaller than the head of a pin, with applications in computers as well as general timekeeping. One of many fascinating things going on at The University of Central Florida"
There's a link of for this story on the NY times at the bottom of the page.
I figure i'd post it here for reference:
And here it is.
that that is is that that is not is not
When reading up on the atomic clock on this site, I read mention aobut the mercury ion clock which would be, when finished, 1000 times more accurate than the standard caesium atomic clock: http://whyfiles.org/078time/2.html
More competition for the new laser-clock, but at 1008 Billion signals per second, I see a major advantage in his laser-research.
Peter Delfyett's area of focus is "increasing the speed of fiber-optic systems" because, according to his research, in the current fibre-optic system:
"beams from several separate lasers, each costing about $1,000, send light wavelengths at the same speed at the same time down the line and the total speed is calculated by multiplying the number of wavelengths by their pulse rates."
Delfyette's current area of research led him to use a "mode-lock laser". This is used to "control the timing and the number of wavelengths that are simultaneously generated"
If you can't see where I'm going with this, think about fibre-optic communications, particularly Fibre-Optic Broadband. This new system can generate 1008 Billion signals per second, each signal having the ability to carry one digital bit, and all this from just one laser, instead of many expensive, bulky convergance lasers. The implications of Peter's new laser-research include the fact that if you had a single fibre-optic fibre for broadband internet access, it would give you a maximum download speed of 120162.9638671875 Megabytes per second, unless I'm mistaken which I could be because my mathematics isn't the best. At any rate, it's much faster than today's fibre-optic broadband connections. Also, since the fibre-optic lines themselves need not be changed, only new laser-systems installed, this technology could be implemented into all current major fibre-optic networks.
I can see Peter's research coming in very handy in the future of land-based communications.
I work for a group that uses and researches mode-locked lasers for a different purpose, and there seem to be a few inaccuracies and misconceptions floating around.
Mode locked lasers have been around since at least 1970, and are widely used for laser and communications research and telecom applications. It's a technology that's getting better as people like Delfyett iron out the substantial kinks, but it's hardly a new technique.
Talking about the size of these things, let's trace a source or two. UCF News release: "smaller than the head of a pin." NY Times: "that potentially could nestle on the head of a pin." Really, the individual optical components (Mach-Zehnder modulator, fiber, electronic oscillator, waveplates, filters, polarization control, isolators, etc.) reqired for a mode locked laser are each at least a few cubic centimeters. With good packaging, you might get a mode locked laser into a lunchbox, but no way as small as a pinhead. That's not to say thirty years down the road they won't have figured out how to put all of these components onto a chip and make it tiny, but it's not happening any time in the next ten years without a serious revolution in optics miniturization.
Mode locked lasers utility as a clock is limited to very fast things, as they're not good clocks for long periods of time. The numerical measure that is quoted for clock accuracy (-140 dBc/Hz, for those of you that follow the stuff) isn't good for time periods longer than 0.1 microseconds. Go below 1-10 MHz (more than 1 - 0.1 microseconds worth of time) or so, and the inaccuracy goes up exponentially for any mode locked laser. Now, that's a thousand clock ticks for a GHz processor, so it's fine for chip clocks. Just don't try timing anything that takes a millisecond.
Compare this to atomic clocks, which get worse over these short time scales, but much, much better over any human time scale. There are physics-based reasons for this, mostly involving the temperature, vibration, and other nusiance noises applied to a few very simple atoms suspended in a shielded vacum trap vs the stability of a bunch of optical components in a box that constantly have optical and electrical power flowing through them.
This is why NIST is looking at linking the two types of clock, not replacing one with the other.
BMagneton
They watch interference patterns. There are mathematical ways to measure infinitesimaly small pulses as long as they repeat in a predictable pattern. Essentialy, they have written a mathematical proof that the device which they built resonates at 1 THz.