Optical circuit and linear system dedicated node apparatus, linear system WDM network, and tree system WDM network using such

• US 20070104488A1
• Filed: 12/22/2006
• Published: 05/10/2007
• Est. Priority Date: 07/09/2004
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yoshida, Setsuo, Miyata, Hideyuki, Kai, Yutaka
• Application Number:
  US11/643,976
• Publication Number:
  US 20070104488A1
• Time in Patent Office: Days
• US Class Current: 398/83
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0205 Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04J 14/0216 Bidirectional architectures

Abstract

The optical circuit is attachable to a ring system dedicated node apparatus, which performs add/drop on an optical signal received from a first network and transmits to a second network, so as to convert into a linear system dedicated node apparatus that performs add/drop on an optical signal received from the first or second network and transmit to the second or first network. The optical circuit includes an optical filter having a characteristic of reflecting an optical signal band supplied from the second network and transmitting an optical signal band supplied from the first network, and transmitting an occupied band of an add light in the ring system dedicated node apparatus to which the own circuit is attached at a predetermined transmission rate and reflecting the reminder. The ring system dedicated node apparatus is used in common with a part of the linear system dedicated node apparatus.

Claims

1. An optical circuit that is attachable to a ring system dedicated node apparatus, which performs add/drop on an optical signal received from a first network and transmits to a second network, so as to convert the ring system dedicated node apparatus into a linear system dedicated node apparatus that performs add/drop on an optical signal received from the first or second network and transmit to the second or first network, the optical circuit comprising:

an optical filter having a characteristic of reflecting an optical signal band supplied from the second network and transmitting an optical signal band supplied from the first network, and transmitting an occupied band of an add light in the ring system dedicated node apparatus to which the own circuit is attached at a predetermined transmission rate and reflecting the reminder.

2. An optical circuit that is attachable to a ring system dedicated node apparatus, which performs add/drop on an optical signal received from a first network and transmits to a second network, so as to convert the ring system dedicated node apparatus into a linear system dedicated node apparatus that performs add/drop on an optical signal received from the first or second network and transmit to the second or first network, the optical circuit comprising:

a first circulator connected to the first network;

a second circulator connected to the second network;

a first filter that transmits an optical signal band received from said first network and supplied through said first circulator, and reflects an optical signal band received from said second network and supplied through said second circulator; and

a second filter that transmits an optical signal band received from said first network and supplied through said first circulator, and reflects an optical signal band received from said second network and supplied through said second circulator with respect to an optical signal transmitted from said ring system dedicated node apparatus, and transmits an occupied band of an add light in said ring system dedicated node apparatus at a predetermined transmission rate and reflects the reminder, and transmits the transmitted optical signal to said second network through said second circulator and transmits the reflected optical signal to said first network through said first circulator.

3. The optical circuit as claimed in claim 2, wherein said predetermined transmission rate is set in accordance with a position of a network where said linear system dedicated node apparatus is located.

4. The optical circuit as claimed in claim 3, wherein said predetermined transmission rate is about 50% when said linear system dedicated node apparatus is in a vicinity of a center of a network.

5. The optical circuit as claimed in claim 3, wherein said predetermined transmission rate is a value such that an add light transmitted toward the center of the network is increased when said linear system dedicated node apparatus is in a vicinity of an end part of the network.

6. The optical circuit as claimed in claim 2, wherein at least one of said first and second filters is constituted by a variable optical filter.

7. The optical circuit as claimed in claim 2, further comprising:

a first variable optical attenuator inserted and connected between said first circulator and said first filter; and

a second variable optical attenuator inserted and connected between said second circulator and said first filter.

8. The optical circuit as claimed in claim 2, further comprising:

a first optical amplifier inserted and connected between said first circulator and said first filter; and

a second optical amplifier inserted and connected between said second circulator and said first filter.

9. A linear system dedicated node apparatus that is constituted by attaching the optical circuit as claimed in claim 2 to a ring system dedicated node apparatus, which performs add/drop on an optical signal received from a first network and transmits to a second network, so as to perform add/drop on an optical signal received from the first or second network and transmit to the second or first network.

10. A linear system WDM network configured by connecting a plurality of the linear system dedicated node apparatuses as claimed in claim 9.

11. A tree system WDM network configured by connecting a plurality of the tree system WDM networks as claimed in claim 10 by a star coupler.

12. The tree system WDM network as claimed in claim 11, wherein occupied bands of the add light in the linear system dedicated node apparatuses are different from each other.