Wavelength division multiplexing passive optical network system

• US 20040033076A1
• Filed: 08/05/2003
• Published: 02/19/2004
• Est. Priority Date: 08/06/2002
• Status: Active Grant

• Current Assignee: Jun-Kook Choi
• Original Assignee: Jun-Kook Choi
• Inventors: Lee, Jong-Hoon, Park, No-Wook, Song, Jae-Won, Jeon, Man-Shik, Seo, Jun-Hyok, Jang, Suck-Woo, Baek, Jang-Ki
• Granted Patent: US 7,254,332 B2
• Time in Patent Office: Days
• US Class Current: 398/70
• CPC Class Codes: H04J 14/0216 Bidirectional architectures
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0252 Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/028 WDM bus architectures
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0293 Optical channel protection
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)

Abstract

Disclosed is a wavelength division multiplexing passive optical network (WDM PON) system in which an optical signal outputted from a central office is injected into a Fabry-Perot laser diode (F-P LD) as the light source of an optical network unit, so that the output wavelength of the optical network unit is injection-locked at the same wavelength as that of the optical signal outputted from the central office, thereby enabling the optical network unit to output an optical signal having the same wavelength as that of the optical signal outputted from the central office. In accordance with this system, it is possible to transmit and receive forward and backward data at the same wavelength by the unit of channels. Since inexpensive F-P LDs are used as respective light sources of the central office and optical network units, it is possible to efficiently and economically implement a WDM PON system.

Claims

1. A wavelength division multiplexing passive optical network (WDM PON) system comprising:

a central office for generating optical signals of different wavelengths, multiplexing the generated optical signals, and outputting the resultant multiplexed optical signal to an optical communication line, the central office receiving an optical signal having the same wavelengths as those of the generated optical signals, and demultiplexing the received optical signal;

a remote node for demultiplexing the optical signal transmitted from the central office via the optical communication line, and outputting the resultant demultiplexed optical signals to distributed optical communication lines, respectively, the remote node multiplexing optical signals respectively transmitted from the distributed optical communication lines, and outputting the resultant multiplexed optical signal to the optical communication line; and

a plurality of optical network units for receiving the optical signals transmitted from the remote node via the distributed optical communication lines, respectively, each of the optical network units generating an optical signal having the same wavelength as that of the optical signal received thereto, and transmitting the generated optical signal to the remote node through an associated one of the distributed optical communication lines.

2. The WDM PON system according to claim 1, wherein the central office comprises:

a plurality of first transmitters for generating and outputting optical signals of different wavelengths, respectively;

a plurality of first receivers for receiving optical signals having the same wavelengths as those of the optical signals outputted from the first transmitters, respectively;

a first multiplexer/demultiplexer for multiplexing the optical signals respectively outputted from the first transmitters, and outputting the resultant multiplexed optical signal, the first multiplexer/demultiplexer demultiplexing the multiplexed optical signal transmitted from the remote node, and outputting the resultant demultiplexed optical signals; and

a plurality of first optical splitters for distributing the demultiplexed optical signals outputted from the first multiplexer/demultiplexer to respective first transmitters and respective second transmitters.

3. The WDM PON system according to claim 2, wherein each of the first transmitters is injection-locked by the optical signal distributed by an associated one of the first optical splitters.

4. The WDM PON system according to claim 2, wherein the optical signals outputted from the first transmitters have the same wavelengths as those of the optical signals transmitted from the remote node, respectively.

5. The WDM PON system according to claim 1, wherein the remote node comprises:

a second multiplexer/demultiplexer for demultiplexing the multiplexed optical signal transmitted from the central office, and transmitting the resultant demultiplexed optical signals to the optical network units, respectively, the second multiplexer/demultiplexer multiplexing the optical signals respectively transmitted from the optical network units, and transmitting the resultant multiplexed optical signal to the central office.

6. The WDM PON system according to claim 1, wherein each of the optical network units comprises:

a second transmitter for generating and outputting an optical signal having the same wavelength as that of an associated one of the demultiplexed optical signals outputted from the remote node;

a second receiver for receiving the associated optical signal outputted from the remote node; and

a second optical splitter for distributing the associated optical signal outputted from the remote node to the second transmitter and the second receiver.

7. The WDM PON system according to claim 6, wherein the second transmitter is injection-locked by the associated optical signal distributed by the second optical splitter.

8. The WDM PON system according to claim 6, wherein the optical signal outputted from the second transmitter has the same wavelength as that of an associated one of the optical signals generated from the central office.

9. The WDM PON system according to claim 1, further comprising:

a bi-directional optical amplifier installed on the optical communication line.

10. A ring type wavelength division multiplexing passive optical network (WDM PON) system comprising:

a central office including a first multiplexer/demultiplexer adapted to perform a multiplexing/demultiplexing operation for normal signals to be used in a normal state, and a second multiplexer/demultiplexer adapted to perform a multiplexing/demultiplexing operation self-healing signals to be used for a self-healing purpose, the central office generating optical signals of N different wavelengths, each of the first and second multiplexers/demultiplexers multiplexing the generated optical signals, and transmitting the resultant multiplexed optical signal to optical network units through a single optical fiber, while demultiplexing a multiplexed optical signal received from the single optical fiber, thereby detecting data generated from the optical network units; and

remote nodes respectively including bi-directional add/drop devices connected to respective optical network units, the remote nodes establishing a ring type distribution network in cooperation with the first and second multiplexers/demultiplexers of the central office, each of the bi-directional add/drop devices including first and second WDM filters respectively having opposite signal travel directions, the first WDM filter performing an add/drop operation for associated ones of the normal signals, the second WDM filter performing an add/drop operation for associated ones of the self-healing signals.

11. The ring type WDM PON system according to claim 10, wherein the first multiplexer/demultiplexer of the central office performs the same multiplexing/demultiplexing operation for the normal signals in both cases in which the normal signals travel in forward and backward directions, respectively.

12. The ring type WDM PON system according to claim 10, wherein the first multiplexer/demultiplexer of the central office performs the same multiplexing/demultiplexing operation for the self-healing signals in both cases in which the self-healing signals travel in forward and backward directions, respectively.

13. The ring type WDM PON system according to claim 10, wherein each WDM filter included in each bi-directional add/drop device drops an optical signal having a selected wavelength from optical signals of N different wavelengths inputted to an input port thereof, to a drop port thereof in accordance with a reflection operation thereof, and transmits the optical signals of the remaining wavelengths through an output port thereof, while reversibly reflecting an optical signal having the selected wavelength inputted to the drop port toward the input port to output the reflected optical signal to the central office.

15. The bus type WDM PON system according to claim 10, wherein the multiplexing/demultiplexing operation of the central office is carried out in the same manner in both cases in which optical signals travel in forward and backward directions, respectively.

14. A bus type wavelength division multiplexing passive optical network (WDM PON) system including a central office, and a remote node connected to the central office via a single optical fiber while being connected to a plurality of optical network units via optical fibers, respectively,

wherein the central office generates optical signals of N different wavelengths, multiplexes the generated optical signals through a multiplexer, transmits the resultant multiplexed optical signal to the remote node through the single optical fiber, receives a multiplexed optical signal from the remote node, and demultiplexes the received multiplexed optical signal through a demultiplexer, thereby detecting data generated from the optical network units;

and

wherein the remote node includes bi-directional add/drop elements connected to respective optical network units, thereby establishing a bus type distribution network, each of the bi-directional add/drop elements drops an optical signal having a selected wavelength from optical signals of N different wavelengths inputted to an input port thereof, to a drop port thereof in accordance with a reflection operation thereof, and transmits the optical signals of the remaining wavelengths through an output port thereof, while reversibly reflecting an optical signal having the selected wavelength inputted to the drop port toward the input port to output the reflected optical signal to the central office.

16. The bus type WDM PON system according to claim 14, wherein each of the add/drop element is a WDM thin film filter having an input port, an output port, and a drop port, the WDM thin film filter dropping an optical signal having a selected wavelength from optical signals of N different wavelengths inputted to the input port thereof, to the drop port thereof in accordance with a reflection operation thereof, and transmitting the optical signals of the remaining wavelengths through the output port thereof, while reversibly reflecting an optical signal having the selected wavelength inputted to the drop port thereof toward the input port.