US4368543A
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Multimode fiber lightwave communication system utilizing pulse self-confinement
Assignee: AT&T Inc
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Filing: 1981-02-02
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Granted: 1983-01-11
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Expires: 2001-02-02
Abstract
Abstract A multimode fiber lightwave communication system using pulses of center wavelength in the region of anomalous dispersion of the fiber material. For instance, in silica-based fiber, this implies a wavelength greater than about 1.3 μm. In such a system, modal dispersion can be reduced by using the nonlinear properties of the fiber material. In particular, by adjusting the pulse amplitude to satisfy the expression ##EQU1## where v gj is the group velocity of the j-th mode, v o is the group velocity of the pulse, f o is the center frequency of the pulse, n o is the field-independent effective refractive index of the fiber at f o , n 2 is the quadratic coefficient of the refractive index of the fiber at f o , |φ| is the absolute magnitude of the peak electric field in the pulse averaged over the cross-section of the guiding region, and α is a constant approximately equal to 1/2, all modes whose group velocity satisfy the expression are "trapped", i.e., are prevented from spreading. The reduced mode dispersion permits e.g., operation of lightwave communication systems at increased data rates.
Inventors
- 👤 Akira Hasegawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:08
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2581
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
177 words
A multimode fiber lightwave communication system using pulses of electromagnetic radiation of center frequency f o and group velocity v o , the system comprising (a) means for generating the pulse with f o such that (∂v gj /∂k j )>0 in the guiding region of the fiber, and (b) means for coupling at least a part of the energy in the pulse into the guiding region of the fiber, CHARACTERIZED IN THAT (c) the electric field of the pulse in the guiding region satisfies ##EQU9## for at least one mode of mode number j, wherein v gj is the group velocity of the j-th mode, k j is the wavenumber of the j-th mode, n o is the field-independent effective refractive index of the fiber at f o , n 2 is the quadratic coefficient of the refractive index of the fiber at f o . |Φ| is the absolute magnitude of the peak electric field in the pulse averaged over the cross-section of the guiding region, and α is a constant approximately equal to 1/2.
Claim 2
Dependent Claim
177 words
A multimode fiber lightwave communication system using pulses of electromagnetic radiation of center frequency f o and group velocity v o , the system comprising (a) means for generating the pulse with f o such that (∂v gj /∂k j )>0 in the guiding region of the fiber, and (b) means for coupling at least a part of the energy in the pulse into the guiding region of the fiber, CHARACTERIZED IN THAT (c) the electric field of the pulse in the guiding region satisfies ##EQU9## for at least one mode of mode number j, wherein v gj is the group velocity of the j-th mode, k j is the wavenumber of the j-th mode, n o is the field-independent effective refractive index of the fiber at f o , n 2 is the quadratic coefficient of the refractive index of the fiber at f o . |Φ| is the absolute magnitude of the peak electric field in the pulse averaged over the cross-section of the guiding region, and α is a constant approximately equal to 1/2.
Claim 3
Dependent Claim
157 words
A multimode fiber lightwave communication system having link length L n and maximum data transmission rate B n when operated with input signals to the fiber of amplitude A and center frequency f o , the system comprising (a) means for generating pulses of electromagnetic energy of center frequency f o , (b) a multimode fiber link of length L n having a transmitter end and a receiver end, (c) means for coupling pulses of amplitude A into the guiding region of the fiber at the transmitter end, and, (d) means for detecting the signals at the receiver end CHARACTERIZED IN THAT the system has a rate-length product L n B n ≧1.05 B e L e , with B e L e determined for the linear system operated with pulses of amplitude A and center frequency f o , wherein B e is the linear maximum data transmission rate, and L e the linear link length.
Claim 4
Dependent Claim
157 words
A multimode fiber lightwave communication system having link length L n and maximum data transmission rate B n when operated with input signals to the fiber of amplitude A and center frequency f o , the system comprising (a) means for generating pulses of electromagnetic energy of center frequency f o , (b) a multimode fiber link of length L n having a transmitter end and a receiver end, (c) means for coupling pulses of amplitude A into the guiding region of the fiber at the transmitter end, and, (d) means for detecting the signals at the receiver end CHARACTERIZED IN THAT the system has a rate-length product L n B n ≧1.05 B e L e , with B e L e determined for the linear system operated with pulses of amplitude A and center frequency f o , wherein B e is the linear maximum data transmission rate, and L e the linear link length.
Claim 5
Dependent Claim
120 words
A multimode fiber light wave communication system using pulses of electromagnetic radiation of center frequency f o , the fiber having a transmitter end and a guiding region comprising material having anomalous dispersion for radiation of frequency f o , the system comprising (a) means for generating the pulses with center frequency f o , (b) means for coupling at least part of the energy in the pulse into the guiding region at the transmitter end of the fiber, CHARACTERIZED IN THAT (c) the absolute magnitude of the peak electric field of the pulse in the guiding region at the transmitter end of the fiber, averaged over the cross-section of the guiding region, is at least about 10 6 V/m.
Claim 6
Dependent Claim
120 words
A multimode fiber light wave communication system using pulses of electromagnetic radiation of center frequency f o , the fiber having a transmitter end and a guiding region comprising material having anomalous dispersion for radiation of frequency f o , the system comprising (a) means for generating the pulses with center frequency f o , (b) means for coupling at least part of the energy in the pulse into the guiding region at the transmitter end of the fiber, CHARACTERIZED IN THAT (c) the absolute magnitude of the peak electric field of the pulse in the guiding region at the transmitter end of the fiber, averaged over the cross-section of the guiding region, is at least about 10 6 V/m.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-10 | 1986-07-12 | 1987-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-10 | 1990-07-12 | 1991-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-10 | 1994-07-12 | 1995-01-11 | $7700.00 | Window Closed / Lapsed |