BIDIRECTIONAL WAVELENGTH-DIVISION-MULTIPLEXED PASSIVE OPTICAL NETWORK

• US 20090208212A1
• Filed: 08/04/2008
• Published: 08/20/2009
• Est. Priority Date: 02/19/2008
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Lee, Kwan-Il, Lee, Sang-Bae
• Granted Patent: US 8,135,278 B2
• Time in Patent Office: Days
• US Class Current: 398/72
• CPC Class Codes: H04B 10/032 using working and protection systems H04J14/0287 takes precedence
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• 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 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)

Abstract

Provided is a bidirectional wavelength division multiplexed passive optical network (WDM-PON) which includes a central office (CO) that transmits and receives multiplexed optical signals, a remote node (RN) that communicates with the CO, receives a multiplexed optical signal to demultiplex, and receives a demultiplexed optical signal to multiplex, an optical network unit (ONU) that transmits and receives demultiplexed optical signals to and from the RN, operational and protective backbone optical fibers that connect the CO to the RN, and operational and protective distribution optical fibers that connect the RN to the ONU. The ONU transmits and receives optical signals through the operational distribution optical fiber and the operational backbone optical fiber, and, where a failure occurs in the operational distribution optical fiber or the operational backbone optical fiber, the ONU transmits and receives optical signals through the protective distribution optical fiber and the protective backbone optical fiber.

Claims

1. A bidirectional wavelength division multiplexed passive optical network (WDM-PON) comprising:

a central office (CO) that transmits and receives multiplexed optical signals;

a remote node (RN) that communicates with the CO, receives a multiplexed optical signal to demultiplex, and receives a demultiplexed optical signal to multiplex;

an optical network unit (ONU) that transmits and receives demultiplexed optical signals to and from the RN;

operational and protective backbone optical fibers that connect the CO to the RN; and

operational and protective distribution optical fibers that connect the RN to the ONU,

wherein the ONU transmits and receives optical signals through the operational distribution optical fiber and the operational backbone optical fiber, and where a failure occurs in the operational distribution optical fiber or the operational backbone optical fiber, the ONU transmits and receives optical signals through the protective distribution optical fiber and the protective backbone optical fiber.

2. The bidirectional WDM-PON according to claim 1, wherein the CO comprises:

an optical transceiver that transmits and receives optical signals;

an arrayed waveguide grating (AWG) that wavelength-division multiplexes the optical signal transmitted from the optical transceiver and wavelength-division demultiplexes the optical signal received into the optical transceiver;

an optical coupler that couples or separates the optical signal transmitted from the optical transceiver and the optical signal received into the optical transceiver to or from each other; and

an incoherent light source that provides seed light for generating an optical signal to the optical transceiver and the ONU.

3. The bidirectional WDM-PON according to claim 2, wherein the optical coupler is a 2×

2 optical coupler.

4. The bidirectional WDM-PON according to claim 2, wherein the CO further comprises a plurality of WDM couplers and an optical circulator.

5. The bidirectional WDM-PON according to claim 2, wherein the optical transceiver receives the seed light from the incoherent light source and transmits an optical signal having the same wavelength as that of the seed light.

6. The bidirectional WDM-PON according to claim 5, wherein the optical transceiver is a Fabry-Perot laser, of which the entire surface is subjected to antireflection coating, or a reflective semiconductor optical amplifier (RSOA).

7. The bidirectional WDM-PON according to claim 1, wherein the RN comprises an N×

N AWG where N represents a natural number.

8. The bidirectional WDM-PON according to claim 7, wherein where the multiplexed optical signal is input to an N-th port of the N×

N AWG, demultiplexed optical signals are output from first to (N−

1)th ports of the N×

N AWG in the side opposite to the N-th port.

9. The bidirectional WDM-PON according to claim 1, wherein the ONU receives seed light for generating an optical signal from the CO via the RN, and transmits an optical signal having the same wavelength as that of the received seed light.

10. The bidirectional WDM-PON according to claim 1, wherein the ONU comprises:

an optical signal monitor that measures an intensity of an optical signal received from the RN through the operational distribution optical fiber;

an optical switching element that is selectively connected to the operational distribution optical fiber or the protective distribution optical fiber;

an optical transceiver that is connected to the optical switching element so as to transmit and receive optical signals; and

a control unit that connects the optical switching element to the protective distribution optical fiber where a failure occurs in the optical signal measured by the optical signal monitor.

11. The bidirectional WDM-PON according to claim 10, wherein the optical transceiver receives seed light for generating an optical signal from the CO via the RN, and transmits an optical signal having the same wavelength as that of the received seed light.

12. The bidirectional WDM-PON according to claim 11, wherein the optical transceiver is a Fabry-Perot laser, of which the entire surface is subjected to antireflection coating, or an RSOA.