US5828477A
Expired / Lapsed
US
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Multi-tone phase modulation for light wave communication system
Assignee: Aurora Networks Inc
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Filing: 1995-11-16
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Granted: 1998-10-27
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Expires: 2015-11-16
Abstract
Abstract An optical transmission system enables launching at least 17 dBm of optical power at 1550 nm wavelength into an e.g. 50 km long span of standard telecommunications single-mode optical fiber, without incurring unacceptable penalties from stimulated Brillouin scattering, damage to optical phase modulators from excessive drive power or thermal effects, or signal degradations caused by the SBS suppression. High frequency modulation of the laser drive current is combined with lower frequency modulation of the phase of the laser output light that is itself varied over a range of approximately 25 MHz. This two tone modulation raises the SBS threshold to greater than 17 dBm in the 1550 nm wavelength region when the laser has a line width less than 10 MHz, under cw operation. By thereby dividing the task of spectral partitioning between the laser and the phase modulator, the RF input power level to the phase modulator is manageable and the laser operates in a regime that does not cause clipping.
Inventors
- 👤 Alan C. Nilsson
- 👤 Chien-Yu Kuo
- 👤 Joseph Kleefeld
- 👤 Charles H. Gall
- 👤 Alfred Nicholson Riddle
- 👤 Harry Chou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 09:24
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2507; H04B10/2537
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
107 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; and a second source of a second frequency signal driving the light source; wherein the second source includes a DC current source and an oscillator providing an alternating current, to drive the light source with a second high frequency signal.
Claim 2
Dependent Claim
107 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; and a second source of a second frequency signal driving the light source; wherein the second source includes a DC current source and an oscillator providing an alternating current, to drive the light source with a second high frequency signal.
Claim 3
Dependent Claim
17 words
The system of claim 1, wherein the first frequency signal is at a frequency exceeding 1 GHz.
Claim 4
Dependent Claim
21 words
The system of claim 1, wherein the first frequency signal and the second frequency signal are not commensurate to one another.
Claim 5
Dependent Claim
46 words
The system of claim 1, wherein the first and second frequency signals are designated f 1 and f 2 and are non-commensurate to one another wherein there are no solutions to the equation Mf 1 =Nf 2 , M and N being integers less than 10.
Claim 6
Dependent Claim
14 words
The system of claim 1, wherein the first frequency signal is of non-constant frequency.
Claim 7
Dependent Claim
142 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the first source includes: a frequency dither generator having an output terminal; a voltage controlled oscillator operating at at least 1 GHz, having a control terminal connected to the output terminal of the frequency dither generator; and a power amplifier having an input terminal coupled to an output terminal of the oscillator and an output terminal coupled to drive the phase modulator.
Claim 8
Dependent Claim
142 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the first source includes: a frequency dither generator having an output terminal; a voltage controlled oscillator operating at at least 1 GHz, having a control terminal connected to the output terminal of the frequency dither generator; and a power amplifier having an input terminal coupled to an output terminal of the oscillator and an output terminal coupled to drive the phase modulator.
Claim 9
Dependent Claim
114 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the second source includes: an oscillator having an output terminal; a frequency doubler coupled to the output terminal of the oscillator; and a power amplifier coupled to an output terminal of the frequency doubler.
Claim 10
Dependent Claim
114 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the second source includes: an oscillator having an output terminal; a frequency doubler coupled to the output terminal of the oscillator; and a power amplifier coupled to an output terminal of the frequency doubler.
Claim 11
Dependent Claim
112 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the first source outputs a signal having a frequency of 2.15±0.01 GHz with excursions of less than 50 MHz, and the second source outputs a signal having a frequency of 5.31±0.01 GHz.
Claim 12
Dependent Claim
112 words
An optical fiber transmission system comprising: a light source outputting a light beam which is coupled to an optical phase modulator; an intensity modulator driven by an information-carrying RF signal and coupled to an output port of the phase modulator; a connector for connecting an output port of the intensity modulator to an optical fiber; a first source of a first frequency signal driving the phase modulator; a second source of a second frequency signal driving the light source; wherein the first source outputs a signal having a frequency of 2.15±0.01 GHz with excursions of less than 50 MHz, and the second source outputs a signal having a frequency of 5.31±0.01 GHz.
Claim 13
Dependent Claim
77 words
An optical fiber transmission system comprising: means for outputting a light beam; means for modulating the means for outputting a light beam at a first high frequency wherein the means for modulating provides an alternating current; means coupled to the output light beam for modulating the light beam at a second frequency; means for intensity modulating the modulated light beam with an information-bearing signal; and means for coupling the intensity modulated light beam to an optical fiber.
Claim 14
Dependent Claim
77 words
An optical fiber transmission system comprising: means for outputting a light beam; means for modulating the means for outputting a light beam at a first high frequency wherein the means for modulating provides an alternating current; means coupled to the output light beam for modulating the light beam at a second frequency; means for intensity modulating the modulated light beam with an information-bearing signal; and means for coupling the intensity modulated light beam to an optical fiber.
Claim 15
Dependent Claim
16 words
The system of claim 9, wherein the first and second frequencies are non-commensurate to one another.
Claim 16
Independent Claim
85 words
A method of transmitting an optical signal through a fiber thereby to suppress stimulated Brillouin scattering, the method comprising the steps of: providing a light beam from a source; modulating the source of the light beam at a first frequency by applying a direct current and a high frequency alternating current to the source; phase modulating the light beam at a second frequency; intensity modulating by an RF information-carrying signal the phase modulated light beam; and coupling the intensity modulated light beam to the fiber.
Claim 17
Independent Claim
85 words
A method of transmitting an optical signal through a fiber thereby to suppress stimulated Brillouin scattering, the method comprising the steps of: providing a light beam from a source; modulating the source of the light beam at a first frequency by applying a direct current and a high frequency alternating current to the source; phase modulating the light beam at a second frequency; intensity modulating by an RF information-carrying signal the phase modulated light beam; and coupling the intensity modulated light beam to the fiber.
Claim 18
Dependent Claim
12 words
The method of claim 11, wherein the high frequency exceeds 1 GHz.
Claim 19
Dependent Claim
15 words
The method of claim 11, further comprising the step of dynamically varying the second frequency.
Claim 20
Dependent Claim
16 words
The method of claim 11, wherein the first and second frequencies are non-commensurate to one another.
Claim 21
Dependent Claim
13 words
The system of claim 1, wherein the light source is a DFB laser.
Claim 22
Dependent Claim
17 words
The system of claim 15, wherein the DFB laser outputs light having a wavelength of 1550 nm.
Claim 23
Dependent Claim
17 words
The system of claim 1, further comprising an erbium doped fiber amplifier coupled to the optical fiber.
Claim 24
Dependent Claim
16 words
The system of claim 1, wherein the information carrying RF signal is a multi-channel TV signal.
Claim 25
Dependent Claim
17 words
The system of claim 1, wherein the phase modulator and intensity modulator are a single integrated component.
Claim 26
Dependent Claim
15 words
The system of claim 1, wherein the first frequency signal is subject to frequency dithering.
Claim 27
Dependent Claim
11 words
The system of claim 9, wherein the second frequency is non-constant.
Claim 28
Dependent Claim
12 words
The method of claim 11, wherein the source is a DFB laser.
Claim 29
Dependent Claim
15 words
The method of claim 11, wherein the light beam has a wavelength of 1550 nm.
Claim 30
Dependent Claim
13 words
The method of claim 11, further comprising amplifying the intensity modulated light beam.
Claim 31
Dependent Claim
15 words
The method of claim 11, wherein the RF information-carrying signal is a multi-channel TV signal.
Claim 32
Dependent Claim
21 words
The method of claim 11, wherein the steps of phase modulating and intensity modulating are performed in a single integrated component.
Claim 33
Dependent Claim
16 words
The method of claim 11, further comprising the step of frequency dithering the second frequency signal.
Claim 34
Dependent Claim
18 words
The system of claim 1, wherein the first frequency signal at any one time has a single frequency.
Claim 35
Dependent Claim
20 words
The method of claim 11, wherein an any one time the light beam is phase modulated by a single frequency.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-26 | 2002-04-27 | 2002-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-26 | 2006-04-27 | 2006-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-26 | 2010-04-27 | 2010-10-27 | $7700.00 | Window Closed / Lapsed |