OCaml All the Way Down – How Jane Street Builds FPGA Designs [video]

Re:OCaml All the Way Down – How Jane Street Builds FPGA Desi... by datenwolf on Sunday September 30, 2018 @05:08PM (#18108429)

This is wrong on both accounts.

The speed of light in a fiber is only about 70% of speed of light in vacuum.

Modern single mode fiber has very low attenuation (less than 0.01dB/km). But more importantly you don't have to use opto-electrical repeaters to boost the signal. What you do is using purely passive dispersion control by mixing different kinds of fiber and compensate for the rest dispersion using chirped fiber bragg gratings. To boost the signal you splice in rare earth doped fibers (Erbirum, Yttrium) which acts as optically pumped optical amplifier.

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Re:OCaml All the Way Down – How Jane Street Builds FPGA Desi... by zoggenhoff on Sunday September 30, 2018 @09:45PM (#18109453)

When you write "modern" how long ago would that have been installed?

/me trying to get a handle on optical development.

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Re:OCaml All the Way Down – How Jane Street Builds FPGA Desi... by datenwolf on Monday October 01, 2018 @10:14AM (#18112680)

The basic principle has been invented over 30 years ago in 1987: https://ieeexplore.ieee.org/document/4258955

They're used in long haul communication for some 15 years or so. They're especially useful in submarine cables, for the sole reason, that new optical transmission schemes(modulation, wavelength multiplexing and so on) can be implemented by just replacing the equipment on either end, without the need to replace components down there on the seabed.

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