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ubwdm 12/4/2012 | 8:06:43 PM
re: Physicists Find Fiber's Limit "Even if you did, most fiber NL effects scale non-linearly with power spectral density of the source (not total optical power)..."

Where did you get that idea? Have you ever seen
n(w) = n0(w) + n1 * (E*conj(E))
?


ownstock 12/4/2012 | 8:06:36 PM
re: Physicists Find Fiber's Limit Exactly! That equation is only accurate under the assumption of quasi-monochromatic waves, or if you like: pair-wise between individual tones of two complex signals. Consider it this way: when the individual tone powers of the complex multi-tone signal are reduced (spread spectrum), the nonlinear tones (cross products) are reduced proportionate to the square of spread. In simple terms, cut the signal tone powers by 3db by doubling the number of tones, the power of each cross tone drops by 6db. Therefore, spectral density, not total power, is the issue.
ppm 12/4/2012 | 8:06:34 PM
re: Physicists Find Fiber's Limit hahaha

Even math and physics no longer works. Great.

The proof I supplied for applying the central
limit theorem is perfectly valid at any given
time. Having different carriers makes no
difference. Adding a separate phase to each
of N random phases still leaves those phases
random. Proof: If phi_n are uniformly
i.i.d. distributed, so are phi_n+n*omega*t.

As for the NLS, it does not require
quasimonochromatic fields. The E^2 term in
the dielectric constant is the total field
intensity, not any spectral density.

Gosh, too many textbooks will now have to be
rewritten ... or maybe not (!)
ownstock 12/4/2012 | 8:06:07 PM
re: Physicists Find Fiber's Limit Clearly you need to read Agrawal Second Ed Ch 7, in particaluar the first paragraph on page 305 and ask yourself 1) What would the noise spectrum of AM/PM noise look like for complex modulated signals, and having figured that out, 2) could would it interfere with the detected signals, and 3) could it be filtered out 4) how much and how?
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