Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1998-01-26
2001-04-10
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06215567
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical transmitting apparatus and an optical receiving apparatus, and an optical communicating method suitable for use in an optical communicating system for an optical communication network utilizing broad band characteristics of fibers.
The optical communication network can transmit a large volume of information as compared with a network using general copper cables. In recent years, the optical communication network draws attention as a network which provides a multi-media service such as CATV (Cable Television), VOD (Video on Demand) or the like.
FIG. 26
is a block diagram showing an example of an optical communicating system for providing a multi-media service. In an optical communicating system
100
shown in
FIG. 26
, a single station
101
is connected to an optical coupler
102
on a transmission route through one optical fiber
103
, and a plurality (n, here) of subscriber terminals
104
-
1
through
104
-
n
are connected to the optical coupler
102
through respective exclusive optical fibers
103
-
1
through
103
-
n.
Between the station
101
and each of the subscriber terminals
104
-
1
through
104
-
n
, optical signals are transmitted and received in wavelength division multiplexing. Namely, the station
101
can multiplex signals of wavelengths &lgr;
1
through &lgr; n, and transmit and receive the signals through the optical fiber
103
.
The optical coupler
102
demultiplexes the wavelength division multiplexed optical signal fed through the optical fiber
103
into optical signals of wavelengths &lgr;
1
through &lgr; n, and transmits the demultiplexed optical signals to the subscriber terminals
104
-
1
through
104
-
n
through the optical fibers
103
-
1
through
103
-
n
, respectively.
The optical coupler
102
couples optical signals (having wavelengths &lgr;
1
through &lgr; n, respectively) each of a single wavelength incident from the subscriber terminals
104
-
1
through
104
-
n
through the respective optical fibers
103
-
1
through
103
-
n
, and outputs the optical signals as a wavelength division multiplexed signal to the optical fiber
103
on the side of the station
101
.
The above optical communicating system
100
as shown in
FIG. 26
is configured between the station
101
and the subscriber terminals
104
-
1
through
104
-
n
, whereby a routing (data transmission) in a wavelength for each subscriber and a band for each subscriber can be increased.
However, the optical communicating system
100
using the above wavelength division multiplexing technique as shown in
FIG. 26
has a disadvantage such that the number of subscribers is limited to the number of wavelengths which can be multiplexed. If it is desired to increase the number of subscribers, it is considered an optical communicating system
100
A in which the above wavelength division multiplexing system employed in
FIG. 26
is combined with a time division multiplexing system.
Namely, in the optical communicating system
100
A employing the time division multiplexing system as shown in
FIG. 27
, transmit-receive signals for three subscriber terminals
104
-
u
,
104
-
v
and
104
-
w
(u, v, w; different integers from
1
to n) are assigned to optical signals having the same wavelength &lgr; i, and each of the subscriber terminals
104
-
u
,
104
-
v
and
104
-
w
extracts a signal addressed to itself from the optical signals of the same wavelength &lgr; x (x; an integer from
1
to n) from the station
101
using a unique clock signal.
However, the above optical communication network shown in
FIG. 27
has a low extensibility of the network to increase the number of subscribers of the optical communicating system. In addition, there is a possibility that the subscriber terminals
104
-
u
,
104
-
v
and
104
w
may receive a signal addressed to another terminal depending on setting of a clock signal or the like. Therefore, there is required an improvement in security (so-called privacy protection).
In the light of the above problems, an object of the present invention is to provide an optical transmitting apparatus and an optical receiving apparatus, and an optical communicating method, which can accommodate subscribers larger in number than wavelengths multiplexed, while realizing privacy protection.
SUMMARY OF THE INVENTION
The present invention therefore provides an optical transmitting apparatus being able to transmit wavelength division multiplexed optical signals to a plurality of opposite apparatus as destinations over an optical communication network comprising an optical signal generating unit for generating an optical signal for each of the plurality of opposing apparatus using a combination of p (p; an integer not less than 2) optical wavelengths set in advance for each of the plurality of opposite apparatus, and a wavelength division multiplexing transmitting unit for wavelength division multiplexing the optical signals generated by the optical signal generating unit and transmitting the multiplexed optical signals.
The optical transmitting apparatus according to this invention uses a combination of p optical wavelengths set in advance for each of a plurality of opposite apparatus (optical receiving apparatus, receiving side apparatus) to generate optical signals for each of the plural opposite apparatus, and transmits the wavelength division multiplexed optical signals from the wavelength division multiplexing transmitting unit over an optical communication network. It is therefore possible to configure an optical communicating system which can accommodate subscribers m larger in number than wavelengths n which can be wavelength division multiplexed and transmitted so as to efficiently use a transmission band of the optical communication system and increase extensibility of the network while keeping an existing performance of wavelength division multiplexing of the network.
The present invention also provides an optical receiving apparatus comprising a wavelength filtering unit for filtering signals of p (p; an integer not less than 2) optical wavelengths set in advance for each of the optical receiving apparatus among wavelength division multiplexed signals transmitted from a transmitting side apparatus over an optical communication network, p photoelectric converting units for converting the signals of the p optical wavelengths filtered by the wavelength filtering unit into electric signals, and a data restoring unit for restoring data addressed to its own apparatus on the basis of the electric signals converted by the photoelectric converting units.
The optical transmitting apparatus according to this invention uses a combination of p optical wavelengths set in advance for each of a plurality of opposite apparatus (optical receiving apparatus, receiving side apparatus) to generate optical signals for each of the plural opposite apparatus, and transmits the wavelength division multiplexed optical signals from the wavelength division multiplexing transmitting unit over an optical communication network. It is therefore possible to configure an optical communicating system which can accommodate subscribers m larger in number than wavelengths n which can be wavelength division multiplexed and transmitted so as to efficiently use a transmission band of the optical communication system and increase extensibility of the network while keeping an existing performance of wavelength division multiplexing of the network.
The present invention still also provides an optical communicating method comprising the steps of, when a transmitting side apparatus transmits wavelength division multiplexed optical signals to a plurality of receiving side apparatus opposite to the transmitting side apparatus over an optical communication network, on the transmitting side apparatus, generating optical signals for each of the plural receiving side apparatus on the basis of a combination of p (p: an integer not less than 2) optical wavelengths set in advance for each of the plural receiving side apparatus an
Fujitsu Limited
Pascal Leslie
Phan Hanh
Staas & Halsey , LLP
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