Optical communications – Optical repeater system – Monitoring
Reexamination Certificate
2001-06-27
2004-10-12
Phan, Hanh (Department: 2872)
Optical communications
Optical repeater system
Monitoring
C398S173000, C398S181000, C398S006000, C398S011000, C398S018000, C398S030000, C398S033000, C398S037000, C359S333000, C359S341100, C359S341300, C359S341400, C359S337000
Reexamination Certificate
active
06804469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to supervisory control of an optical amplifier repeater system, and particularly to a supervisory system and supervisory method of an optical amplifier repeater system used for long distance optical communications through a submarine cable laid on an ocean floor and the like.
2. Description of Related Art
FIGS. 8-11
are block diagrams showing a conventional supervisory system of the optical amplifier repeater system:
FIG. 9
is a block diagram showing the optical transmitter as shown in
FIG. 8
;
FIG. 10
is a block diagram showing an optical amplifier repeater as shown in
FIG. 8
; and
FIG. 11
is a block diagram showing the optical receiver as shown in FIG.
8
. In
FIG. 8
, each reference numeral
101
designates an optical amplifier repeater, the reference numeral
102
designates an optical transmitter,
103
designates an optical receiver and
104
designates a transmission fiber. The optical amplifier repeater
101
, receiving an optical signal from the optical transmitter
102
through the transmission fiber
104
, amplifies the optical signal, and supplies it to the transmission fiber
104
on the side of the optical receiver
103
.
Next, the operation of the supervisory system of the optical amplifier repeater system as shown in
FIG. 8
will be described. First, the operation of the optical transmitter
102
will be described with reference to
FIG. 9. A
main signal circuit
105
outputs a main signal bearing transmitted information, and an auxiliary signal circuit
106
outputs an auxiliary signal with a lower rate and smaller amplitude than the main signal. The two signals are superimposed so that a modulator
107
modulates the multiplexed signal. A driver
108
drives a semiconductor laser
109
in response to the modulated signal to generate the optical signal. The optical signal is transferred to the transmission fiber
104
(shown in
FIG. 8
) via an internal transmission fiber
110
.
Here, the optical signal output from the semiconductor laser
109
includes a main optical signal and an auxiliary optical signal generated by the electric-optic conversion of the main signal and auxiliary signal, respectively. Thus, the optical signal has such a waveform as modulated by the main signal, on which the low rate auxiliary signal of a small modulation factor is superimposed.
The auxiliary signal from the auxiliary signal circuit
106
consists of an operation command for the individual sections or circuits constituting each optical amplifier repeater
101
to inform about their states for monitoring them. The auxiliary signal includes one of proper address codes uniquely assigned to individual optical amplifier repeaters
101
in advance to specify the optical amplifier repeater
101
to be activated.
When the optical transmitter
102
activates a particular optical amplifier repeater
101
by providing the auxiliary signal with one of the address codes proper to the optical amplifier repeater
101
, it must consider a time period the optical amplifier repeater
101
will take to execute the command and to make a response, and transmits the subsequent operation commands to other optical amplifier repeaters
101
at suitable intervals to avoid overlapping of the response optical signals from a plurality of optical amplifier repeaters
101
.
Next, the operation of the optical amplifier repeater
101
will be described with reference to FIG.
10
. The optical amplifier repeater
101
receives the optical signal via the transmission fiber
104
of
FIG. 8. A
coupler
112
connected to an internal input fiber
111
splits the optical signal, and provides only a small part of the optical signal to a photoelectric converter
121
. Most of the optical signal is supplied to an erbium doped fiber amplifier
113
.
The optical signal entering the erbium doped fiber amplifier
113
passes through an optical isolator
114
, is coupled by a coupling filter
115
with pumping light fed from a pumping laser diode
116
, amplified by an erbium doped fiber
117
, and passes through an optical isolator
118
. A coupler
119
splits the optical signal to extract only a small part of the optical signal as feedback control information. Most of the optical signal is transferred to the transmission fiber
104
as shown in
FIG. 8
via an output fiber
120
.
The photoelectric converter
121
converts the part of the optical signal into an electric signal, and supplies it to an amplifier
122
. The amplifier
122
amplifies the electric signal by a prescribed amount, and supplies it to a lowpass filter
123
. The lowpass filter
123
detects the auxiliary signal from the electric signal, and supplies it to a call identifying section
124
. The call identifying section
124
compares the address code in the auxiliary signal with the address code of the optical amplifier repeater to identify it, and supplies the identification result to an identification controller
125
.
Subsequently, when the identification result of the call identifying section
124
indicates the agreement between the address codes, the identification controller
125
carries out the operation command. For example, when the operation command instructs the notification of level states, the identification controller
125
activates an encoder
126
and a modulator
127
to encode supervisory information indicating whether the levels of various portions are higher or lower than initially set values, and to modulate it to be supplied to the pumping laser diode driver
128
.
The pumping laser diode driver
128
drives the pumping laser diode
116
in accordance with the modulation signal fed from the modulator
127
, and outputs the pumping light which also serves as a response optical signal including the supervisory information. The coupling filter
115
combines the transmitted optical signal with the pumping light to be supplied to the erbium doped fiber
117
.
Thus, the erbium doped fiber
117
amplifies the optical signal based on the pumping light bearing the response optical signal. The amplified optical signal is supplied to the transmission fiber
104
through the output fiber
120
.
A photoelectric converter
130
, receiving part of the optical signal extracted by the coupler
119
, converts the optical signal into an electric signal. An amplifier
131
amplifies the electric signal and supplies it to a feedback controller (not shown). A photodetector
129
detects the output of the pumping laser diode
116
, and feeds the detected signal back to the pumping laser diode driver
128
.
Next, the operation of the optical receiver
103
will be described with reference to FIG.
11
. In the optical receiver
103
that receives the optical signal sent from the optical amplifier repeater
101
through the transmission fiber
104
as shown in
FIG. 8
, a photoelectric converter
133
receives the optical signal through an internal transmission fiber
132
, and converts it into an electric signal. Since the optical signal includes the main optical signal and response optical signal corresponding to the main signal and response signal, they are extracted as the main electric signal and response electric signal.
Subsequently, the amplifier
134
amplifies the electric signals by a prescribed amount. The amplified main electric signal is demodulated by a main signal demodulator
135
as the main signal. A low pass filter
136
extracts the response electric signal. An auxiliary signal demodulator
137
demodulates the response electric signal and outputs the supervisory information. The supervisory information is used as supervisory/control information when operating the optical amplifier repeater
101
.
As described above, according to the conventional supervisory system of the optical amplifier repeater system, each optical amplifier repeater
101
encodes the states of the various sections and circuits in response to the request for the state notification, and transmits the information about the states to the optical receiver
103
. For
Goto Hideki
Horiuchi Yukio
Ishii Daishi
Kasahara Yasunori
Kawazawa Toshio
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