Optical communications – Optical repeater system – Monitoring
Reexamination Certificate
2002-10-03
2004-11-16
Phan, Hanh (Department: 2633)
Optical communications
Optical repeater system
Monitoring
C398S079000, C398S181000, C398S173000, C398S006000, C398S037000, C398S011000, C398S018000, C398S030000, C398S031000, C398S033000, C398S038000, C359S341430, C359S337000
Reexamination Certificate
active
06819875
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an optical wavelength multiplexing transmission apparatus and optical output control method for the optical wavelength multiplexing transmission apparatus, suitable for use in an optical wavelength multiplexing transmission system including an optical wavelength multiplexing terminating set and an optical wavelength multiplexing repeater, using an optical direct amplifier, particularly for an optical wavelength multiplexing transmission system including a linear optical wavelength multiplexing repeater.
BACKGROUND ART
For fast transmission of a large volume of information, there has been employed a system based on an optical wavelength multiplexing transmission technique. This optical wavelength multiplexing transmission system is for transmitting a wavelength-multiplexed light with different wavelengths through one optical fiber. In recent years, an optical wavelength multiplexing transmission system, which provides a transmission rate of approximately 2.4 Gbps×16 waves (where “G” represents 10
9
and “bit per second” signifies transmission rate per second) has been put to practical use.
Furthermore, on the design of a transmission line used for the optical wavelength multiplexing transmission, it is technically required to suppress the non-linear effects of an optical fiber. Still furthermore, in a case in which the aforesaid optical wavelength multiplexing transmission system is used as a linear repeating system, the key is maintaining the gain fattening in an optical band the optical amplifier puts to use. For this reason, as one example of meeting such a technical requirement, there is a method in which an optical amplifier is controlled through the use of ALC (Automatic Level Control).
An optical wavelength multiplexing transmission system will first be described with reference to
FIGS. 18
to
20
and an ALC will then be described with reference to
FIGS. 21 and 22
. In the following description, an optical amplifier will sometimes be referred to as an “optical AMP” or simply as an “AMP”, and the contents thereof are the same.
FIG. 18
is a block diagram showing a transmission side WDM (Wavelength Division Multiplexing) terminal station. In
FIG. 18
, a transmission side WDM terminal station
100
a
is an optical wavelength multiplexing transmission apparatus designed to perform the multiplexing for a wavelength-multiplexed light and the demultiplexing thereof, and acts as a transmission terminal station. Moreover, this transmission side WDM terminal station
100
a
is made up of a multiplexing unit (MUX)
16
a
, an up main signal light amplifying unit
31
, an OSC (Optical Supervisory Channel) light transmitting unit
113
b
, a control unit
113
c
and an optical output monitor
113
a.
The multiplexing unit
16
a
accomplishes optical coupling, and the up main signal light amplifying unit
31
compensates for a drop of an optical level at optical multiplexing and dispersion compensation, or in a transmission line or the like. Moreover, the optical output monitor
113
a
monitors an optical output level from a coupler (optical coupler)
60
a
in the up main signal light amplifying unit
31
to issue an output monitor value. This output monitor value is inputted to the control unit
113
c
to implement the output control of the up main signal light amplifying unit
31
and the information transfer to the OSC light transmitting unit
113
b.
In addition, the OSC light transmitting unit
113
b
is for wavelength-multiplexing a sub-signal light, functioning as a control signal, and a main signal light for the purpose of the supervisory control of a remote station (not shown). In this case, the sub-signal light is equally referred to simply as an “OSC light”. This OSC light transmitting unit
113
b
is for carrying out the switching control between the ALC control for automatically controlling the optical output level and the AGC control (Automatic Gain Control) for variably controlling the gain, and further for transmitting the number of transmission wavelengths forming the ALC setting information and the information such as a transmission rate to a linear repeater or reception side WDM terminal station lying on the downstream side. These ALC control and AGC control will be described later with reference to
FIGS. 21 and 22
.
In the following description, a main signal light signifies an optical wavelength-multiplexed signal to be linearly repeated between WDM terminal stations, while an OSC light (sub-signal light) represents a single wavelength light for supervisory control which does not pass through an optical amplifier and which is terminated at each of repeating sections. This OSC light does not affect the passing of a main signal light and does not pass through an optical amplifier, and is used as a supervisory control channel or pilot light. This “pass” signifies that it is in a communication state. Although a WDM terminal station is equally referred to as a “WDM terminal device”, in the following description it sometimes will be referred to simply as an “terminal station”.
Moreover, in
FIGS. 18
to
20
, the same reference numerals as those used above denote the same or equivalent functions, and the further description thereof will be omitted.
FIG. 19
is a block diagram showing a WDM linear repeater. In
FIG. 19
, a WDM linear repeater
100
b
is an optical wavelength multiplexing transmission apparatus, and operates as a linear repeater (linear repeating device) An OSC light transmitted from a former station is received by an OSC light receiving unit
113
d
located on the wavelength-multiplexed light input side and the reception level is inputted as a reception value to the control unit
113
c
. Moreover, a wavelength-multiplexed light outputted from the up main signal light amplifying unit
31
is monitored in the optical output monitor
113
a
and the output monitor value is inputted to the control unit
113
c
. In the control unit
113
c
, an OSC transmission value is calculated on the basis of these values and is outputted to the OSC light transmitting unit
113
b
to be transmitted to an adjacent station (next station). Thus, information is transmitted through the use of an OSC light different from a main signal light.
FIG. 20
is a block diagram showing a reception side WDM terminal station. In
FIG. 20
, a reception side WDM terminal station
100
c
is also constructed as an optical wavelength multiplexing transmission apparatus, and works as a transmission (reception) terminal station. A main signal light from a transmission line is amplified in the up main signal light amplifying unit
31
and, following this, in a demultiplexing unit (DMUX)
16
b
, a received wavelength-multiplexed light is demultiplexed into lights with optical wavelengths &lgr;
1
to &lgr;
8
and then outputted.
In addition, the OSC light is received by the OSC light receiving unit
113
d
and the OSC reception value is inputted to the control unit
113
c
. On the other hand, for the main signal light, an output light level is monitored in the optical output monitor
113
a
and inputted as an output monitor value to the control unit
113
c
. On the basis of these values, the control unit
113
c
outputs an output control signal to a variable attenuator
31
b
in the up main signal light amplifying unit
31
.
As described above, the transmission side WDM terminal station
100
a
, the WDM linear repeater
100
b
and the reception side WDM terminal station
100
c
, shown in
FIGS. 18
to
20
, are connected through optical fiber transmission lines, and a wavelength-multiplexed light comprising a main signal light and an OSC light is transmitted from the transmission side WDM terminal station
100
a
through the downstream side WDM linear repeater
100
b
to the reception side WDM terminal station
100
c.
Furthermore, with respect to the output level control of an optical amplifier, a description will be given hereinbelow of ALC control and AGC control in a case in which the number of wavelengths to be multiplexed increases and
Phan Hanh
Staas & Halsey , LLP
LandOfFree
Optical wavelength multiplexing transmission apparatus and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical wavelength multiplexing transmission apparatus and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical wavelength multiplexing transmission apparatus and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3346652