[time-nuts] Fw: Optical transfer of time and frequency

Tom Van Baak tvb at LeapSecond.com
Sun May 1 15:44:36 UTC 2016


> Has anybody experienced with free-space optical gigabit Ethernet
> links? I am curious about whether the transceivers have a fixed
> latency or at least a latency one can easily quantify online. This is
> the trickiest part for adding WR support on top of a given physical
> layer.

Hi Javier,

When searching this topic I ran across a commercial laser solution:

http://www.laseroptronics.com/products.cfm/product/27-0-0.htm
http://www.laseroptronics.com/index.cfm/id/57-66.htm
http://www.laseroptronics.com/index.cfm/id/57-69.htm
etc.

But, according to /57-67.htm it "starts" at $15k per node. Plus there's the cost of all the WR pieces, assuming the two are even compatible. So this is vastly above the ~$2k budget mentioned by OP. I also assume OP is not ready to embark on a one-off, multi-man-year R&D project.

This particular issue -- how to synchronize (or, at least phase compare) multiple oscillators by a two-way laser link over a few km to within 500 ps -- is really quite interesting. It would, for example, allow me to do live monitoring of 5071A Cs time dilation on my next mountain-valley relativity experiment.

/tvb



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