US5455704A — Optical-fiber light amplifier

Claim 1

Independent Claim 128 words

An optical fiber amplifier comprising: (a) error-signal-generating means connected to receive a light signal, on which a first subcarrier is superposed, and for generating an error signal representative of the difference between the level of said light signal and a predetermined reference level; (b) constant level means for maintaining the level of said light signal at a constant level, responsive to said error signal outputted from said error-signal-generating means; (c) subcarrier-processing means for detecting and processing said first subcarrier responsive to said error signal; and (d) subcarrier-superposing means including means for generating a second subcarrier responsive to the detecting and processing performed by said subcarrier processing means and means for superposing said second subcarrier on the light signal maintained at the constant level by said constant level means.

Claim 2

Dependent Claim 128 words

An optical fiber amplifier comprising: (a) error-signal-generating means connected to receive a light signal, on which a first subcarrier is superposed, and for generating an error signal representative of the difference between the level of said light signal and a predetermined reference level; (b) constant level means for maintaining the level of said light signal at a constant level, responsive to said error signal outputted from said error-signal-generating means; (c) subcarrier-processing means for detecting and processing said first subcarrier responsive to said error signal; and (d) subcarrier-superposing means including means for generating a second subcarrier responsive to the detecting and processing performed by said subcarrier processing means and means for superposing said second subcarrier on the light signal maintained at the constant level by said constant level means.

Claim 3

Dependent Claim 88 words

An optical fiber amplifier according to claim 1, wherein said error-signal-generating means includes: a light-branching coupler for separating the light signal from said first subcarrier superposed thereon; light-receiving means for receiving the light signal from said light-branching coupler and for converting the light signal into an electrical signal; and reference potential generating means for producing a reference signal; differential amplifying means for receiving the electrical signal from said light-receiving means and the reference signal from the reference-potential-generating means and for outputting the difference therebetween as said error signal.

Claim 4

Dependent Claim 77 words

An optical fiber amplifier according to claim 2, wherein said constant level means includes: a first source for emitting excitation light; first driving means for driving said first source, based on said error signal outputted from said differential amplifying means; and a first rare-earth-element-doped optical fiber coupled to the first source, for amplifying to a constant level the light signal, on which said first subcarrier is superposed, responsive to the excitation light emitted from said first source.

Claim 5

Dependent Claim 93 words

An optical fiber amplifier according to claim 3, wherein said subcarrier-processing means includes: means for demodulating said error signal outputted from said differential amplifying means; means for separating a first subcarrier signal from a demodulated error signal outputted from said demodulating means means for processing the first subcarrier signal outputted from said separating means; and superposing means for receiving another demodulated error signal outputted from said separating means and for superposing said another demodulated error signal on said first subcarrier from said processing means to output the resulting signal to said subcarrier-superposing means.

Claim 6

Dependent Claim 96 words

An optical fiber amplifier according to claim 1, wherein said subcarrier-superposing means includes: means responsive to the subcarrier-processing means, for generating a second subcarrier signal; a second source for emitting excitation light; second driving means for driving said second source based on said second subcarrier outputted from said subcarrier-generating means; and a second rare-earth-doped optical fiber responsive to said excitation light emitted from said second source, for superposing said second subcarrier on said light signal, which is maintained at the constant level by said constant level means, by said excitation light emitted from said second source.

Claim 7

Dependent Claim 106 words

A light amplification repeating system with a monitoring function using a light amplifier, said system comprising: (a) error-signal-generating means for receiving a light signal, on which a first subcarrier is superposed, and for generating an error signal according to the difference between the level of said light signal and a predetermined reference level; (b) subcarrier-processing means for detecting and processing said first subcarrier based on said error signal; and (c) subcarrier-superposing means including means for generating a second subcarrier in response to the detecting and processing performed by said subcarrier-processing means and means for superposing said second subcarrier on spontaneous emission light from the light amplifier.

Claim 8

Dependent Claim 106 words

A light amplification repeating system with a monitoring function using a light amplifier, said system comprising: (a) error-signal-generating means for receiving a light signal, on which a first subcarrier is superposed, and for generating an error signal according to the difference between the level of said light signal and a predetermined reference level; (b) subcarrier-processing means for detecting and processing said first subcarrier based on said error signal; and (c) subcarrier-superposing means including means for generating a second subcarrier in response to the detecting and processing performed by said subcarrier-processing means and means for superposing said second subcarrier on spontaneous emission light from the light amplifier.

Claim 9

Dependent Claim 121 words

A light repeating system comprising: (a) subcarrier-transmitting means for receiving part of a light signal on which a first sub-carrier is superposed and for generating a second sub-carrier from said first sub-carrier; (b) pumping-light-source-driving means for outputting a driving signal based on said second sub-carrier outputted from said subcarrier-transmitting means; (c) means for modulating said driving signal, which is outputted from said pumping-light-source-driving means, with a signal whose frequency is higher than that of said second subcarrier; (d) a pumping light source driven by the modulated driving signal outputted from said modulating means; and (e) amplifying means for superposing said second subcarrier on said light signal, on which said first subcarrier is superposed, by excitation light from said pumping light source.

Claim 10

Dependent Claim 121 words

A light repeating system comprising: (a) subcarrier-transmitting means for receiving part of a light signal on which a first sub-carrier is superposed and for generating a second sub-carrier from said first sub-carrier; (b) pumping-light-source-driving means for outputting a driving signal based on said second sub-carrier outputted from said subcarrier-transmitting means; (c) means for modulating said driving signal, which is outputted from said pumping-light-source-driving means, with a signal whose frequency is higher than that of said second subcarrier; (d) a pumping light source driven by the modulated driving signal outputted from said modulating means; and (e) amplifying means for superposing said second subcarrier on said light signal, on which said first subcarrier is superposed, by excitation light from said pumping light source.

Claim 11

Dependent Claim 29 words

A light repeating system according to claim 7, wherein said modulating means includes an adder for adding a sine-wave high-frequency signal of over 600 MHz to said driving signal.

Claim 12

Dependent Claim 29 words

A light repeating system according to claim 7, wherein said modulating means includes an adder for adding a pulse high-frequency signal of over 600 MHz to said driving signal.

Claim 13

Dependent Claim 99 words

A light repeating system with a monitoring function, comprising: (a) subcarrier-transmitting means for receiving part of a light signal on which a first sub-carrier is superposed and for generating a second sub-carrier from said first sub-carrier; (b) pumping-light-source-driving means for outputting a driving signal based on said second sub-carrier outputted from said subcarrier-transmitting means; (c) a self-oscillation pumping light source driven by said driving signal outputted from said pumping-light-source-driving means; and (d) amplifying means for superposing said second subcarrier on said light signal, on which said first subcarrier is superposed, by excitation light from said self-oscillation pumping light source.

Claim 14

Dependent Claim 99 words

A light repeating system with a monitoring function, comprising: (a) subcarrier-transmitting means for receiving part of a light signal on which a first sub-carrier is superposed and for generating a second sub-carrier from said first sub-carrier; (b) pumping-light-source-driving means for outputting a driving signal based on said second sub-carrier outputted from said subcarrier-transmitting means; (c) a self-oscillation pumping light source driven by said driving signal outputted from said pumping-light-source-driving means; and (d) amplifying means for superposing said second subcarrier on said light signal, on which said first subcarrier is superposed, by excitation light from said self-oscillation pumping light source.

Claim 15

Dependent Claim 85 words

A light repeating system composed of a plurality of light repeaters, each with a monitoring function whose elements are located in a light end office, said system comprising: (a) demodulating means located in the light end office for demodulating subcarriers transmitted from the individual light repeaters; and (b) judging means located in the light end office for receiving demodulated subcarriers and for judging when abnormal information contained in said demodulated subcarrier continues for one of a predetermined time period or a predetermined number of occasions.

Claim 16

Dependent Claim 85 words

A light repeating system composed of a plurality of light repeaters, each with a monitoring function whose elements are located in a light end office, said system comprising: (a) demodulating means located in the light end office for demodulating subcarriers transmitted from the individual light repeaters; and (b) judging means located in the light end office for receiving demodulated subcarriers and for judging when abnormal information contained in said demodulated subcarrier continues for one of a predetermined time period or a predetermined number of occasions.

Claim 17

Dependent Claim 146 words

An optic fiber amplifier comprising: a rare earth doped optic fiber connected to carry a light signal; an automatic light level control circuit, including a light level receiver having an light level output and connected to receive the light signal from the doped optic fiber, an error amplifier producing an error signal and connected to receive the light level output and a reference level, and an excitation light source optically coupled to the doped optic fiber and controlled by the error signal; an input subcarrier detector having a data output and connected to receive the light signal; an output subcarrier superposing circuit having a light signal output and connected to receive the data from the input subcarrier detector, the output subcarrier superposing circuit including an output subcarrier generator and a light modulation circuit producing the light signal output including the output subcarrier modulated by the data.

Claim 18

Dependent Claim 146 words

An optic fiber amplifier comprising: a rare earth doped optic fiber connected to carry a light signal; an automatic light level control circuit, including a light level receiver having an light level output and connected to receive the light signal from the doped optic fiber, an error amplifier producing an error signal and connected to receive the light level output and a reference level, and an excitation light source optically coupled to the doped optic fiber and controlled by the error signal; an input subcarrier detector having a data output and connected to receive the light signal; an output subcarrier superposing circuit having a light signal output and connected to receive the data from the input subcarrier detector, the output subcarrier superposing circuit including an output subcarrier generator and a light modulation circuit producing the light signal output including the output subcarrier modulated by the data.

Claim 19

Dependent Claim 113 words

The optic fiber amplifier of claim 12, wherein the automatic light level control circuit further comprises: a light-branching coupler having the light signal as an input and a second light signal output, the second light signal having been separated from the first subcarrier superposed on the light signal; a light signal receiver connected to receive the second light signal and having an electrical signal output representative of the second light signal received; and the error amplifier comprises a differential amplifier having a first input connected to the reference signal, a second input connected to receive the electrical signal from the light signal receiver and the error signal appearing as an output signal thereof.

Claim 20

Dependent Claim 77 words

The optic fiber amplifier of claim 13, the excitation light source having a control input and wherein the automatic light level control circuit further comprises: a driver circuit connected to the control input of the excitation light source and responsive to the error signal output by the differential amplifier; and a first rare-earth-element-doped optical fiber coupled to and pumped by the excitation light source and coupled to receive the light signal, whereby the light signal is amplified.

Claim 21

Dependent Claim 129 words

The optic fiber amplifier of claim 14, wherein the automatic light level control circuit further comprises: a demodulator having the error signal as an input and a demodulated error signal as an output; a subcarrier separating circuit having the demodulated error signal as an input, a first subcarrier signal as an output and a separated demodulated error signal as another output; a subcarrier processing circuit having the first subcarrier signal as an input and a processed first subcarrier signal as an output; and a superposing circuit having the separated demodulated error signal as an input and the first subcarrier as another input, and an output signal formed of a superposition of the first subcarrier and the separated demodulated error signal, the output connected to the output subcarrier superposing circuit.

Claim 22

Dependent Claim 78 words

The optic fiber amplifier of claim 12, further comprising: a second subcarrier generation circuit having the processed first subcarrier signal as an input and a second subcarrier signal as an output; a second excitation light source, having a control input; a second driving circuit connected to the control input of the second excitation light source and responsive to the second subcarrier signal; and a second rare-earth-doped optical fiber coupled to and pumped by the second excitation light source.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-10-02	1999-04-03	1999-10-03	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-10-02	2003-04-03	2003-10-03	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-10-02	2007-04-03	2007-10-03	$7700.00	Window Closed / Lapsed

Optical-fiber light amplifier

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