US5546210A — Multi-channel optical fiber communication system

Claim 1

Independent Claim 176 words

Wavelength division multiplexed optical communication system including: transmitter means containing generator means and modulator means for generating, modulating, and introducing a set of multiplexed channel carries into an optical transmission line, the carries having "carrier wavelengths" within a "total bandwidth" distributed about a "system wavelength"; receiver means including de-multiplexer means for de-multiplexing channel carries; optical amplifiers; and a transmission line of optical fiber including at least one fiber span defined at one end by such transmitter means and at the other end by such receiver means, in which the span includes at least one optical amplifier; wherein the set includes at least 4 channels of wavelengths, λ 1 , λ 2 , λ 3 , λ 4 , with a total bandwidth sufficiently narrow that channel carriers produce four-wave-mixing (4WM) products which limit attainable system capacity characterized in that channel-to-channel frequency spacings are unequal and in that spacing are of such magnitudes as to assure substantial non-coincidence of wavelength of any 4WM product with any channel carrier wavelength, whereby the 4WM limit on capacity is lessened.

Claim 2

Dependent Claim 176 words

Wavelength division multiplexed optical communication system including: transmitter means containing generator means and modulator means for generating, modulating, and introducing a set of multiplexed channel carries into an optical transmission line, the carries having "carrier wavelengths" within a "total bandwidth" distributed about a "system wavelength"; receiver means including de-multiplexer means for de-multiplexing channel carries; optical amplifiers; and a transmission line of optical fiber including at least one fiber span defined at one end by such transmitter means and at the other end by such receiver means, in which the span includes at least one optical amplifier; wherein the set includes at least 4 channels of wavelengths, λ 1 , λ 2 , λ 3 , λ 4 , with a total bandwidth sufficiently narrow that channel carriers produce four-wave-mixing (4WM) products which limit attainable system capacity characterized in that channel-to-channel frequency spacings are unequal and in that spacing are of such magnitudes as to assure substantial non-coincidence of wavelength of any 4WM product with any channel carrier wavelength, whereby the 4WM limit on capacity is lessened.

Claim 3

Dependent Claim 31 words

System of claim 1 in which the ratio of (minimum channel-to-channel spacing) to (minimum spacing of any 4WM product from any channel) is equal to a value of at least 2.

Claim 4

Dependent Claim 31 words

System of claim 1 in which the ratio of (minimum channel-to-channel spacing) to (minimum spacing of any 4WM product from any channel) is equal to a value of at least 5.

Claim 5

Dependent Claim 28 words

System of claim 1 in which the fiber constituting a substantial part of a span has a dispersion value as measured at the system wavelength of 0-4 ps/nm-km.

Claim 6

Dependent Claim 16 words

System of claim 4 in which Dispersion Shifted Fiber constitutes a substantial part of the span.

Claim 7

Dependent Claim 28 words

System of claim 1 in which the fiber constituting a substantial part of a span has a dispersion value as measured at the system wavelength of 1.5-4 ps/nm-km.

Claim 8

Dependent Claim 13 words

System of claim 6 in which the system wavelength is approximately 1550 nm.

Claim 9

Dependent Claim 14 words

System of claim 7 in which the optical amplifier is an erbium-doped fiber amplifier.

Claim 10

Dependent Claim 12 words

System of claim 8 in which the total bandwidth is 30 nm.

Claim 11

Dependent Claim 13 words

System of claim 8 in which the total bandwidth is 10 nm-20 nm.

Claim 12

Dependent Claim 13 words

System of claim 1 in which the set includes at least 4 channels.

Claim 13

Dependent Claim 13 words

System of claim 1 in which the set includes at least 8 channels.

Claim 14

Dependent Claim 16 words

System of claim 1 in which the least channel-to-channel spacing is a maximum of 0.8 nm.

Claim 15

Dependent Claim 14 words

System of claim 1 in which per-channel bit rate is at least 2.5 Gb/sec.

Claim 16

Dependent Claim 14 words

System of claim 1 in which per-channel bit rate is at least 5.0 Gb/sec.

Claim 17

Dependent Claim 23 words

System of claim 1 in which span length is at least 360 km and in which system capacity is at least 10 Gb/sec.

Claim 18

Dependent Claim 14 words

System of claim 16 in which the span includes at least two fiber amplifiers.

Claim 19

Dependent Claim 86 words

System of claim 1 in which the channel-to-channel frequency spacings, m i Δf, i=1, . . . , N-1 where N is the number of channels and Δf is the minimum spacing of any 4WM product from any channel, satisfy the condition that the spacing between any two channels, ##EQU4## must be different from that of any other pair of channels, subject to the constraint that all m i ≧n where n is an integer greater than 1, and nΔf is the minimum allowed channel spacing.

Claim 20

Dependent Claim 132 words

Communication method for an optical fiber communication system comprising: generating a set of at least four channel carriers; modulating the carriers, thereby creating a modulated set of carriers, each constituting a bit stream; multiplexing the modulated carriers; launching the modulated set of carriers onto a single optical fiber; simultaneously passing all members of the modulated set through a single fiber amplifier, in which the bit stream in each channel contains at least 2.5 Gb/sec; and receiving digital signals at a receiver which is at least 360 km distant from the launch point characterized in that channel-to-channel frequency spacings are unequal and in that spacings are of such magnitudes as to assure substantial non-coincidence of wavelength of any 4WM product with any channel carrier wavelength, whereby the 4WM limit on capacity is lessened.

Claim 21

Dependent Claim 132 words

Communication method for an optical fiber communication system comprising: generating a set of at least four channel carriers; modulating the carriers, thereby creating a modulated set of carriers, each constituting a bit stream; multiplexing the modulated carriers; launching the modulated set of carriers onto a single optical fiber; simultaneously passing all members of the modulated set through a single fiber amplifier, in which the bit stream in each channel contains at least 2.5 Gb/sec; and receiving digital signals at a receiver which is at least 360 km distant from the launch point characterized in that channel-to-channel frequency spacings are unequal and in that spacings are of such magnitudes as to assure substantial non-coincidence of wavelength of any 4WM product with any channel carrier wavelength, whereby the 4WM limit on capacity is lessened.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-08-13	2000-02-12	2000-08-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-08-13	2004-02-12	2004-08-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-08-13	2008-02-12	2008-08-13	$7700.00	Window Closed / Lapsed

Multi-channel optical fiber communication system

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