Optical access network using wavelength-locked WDM optical source injected by incoherent light

• US 7,912,372 B2
• Filed: 06/24/2005
• Issued: 03/22/2011
• Est. Priority Date: 12/24/2002
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Park, Keun Youl, Choi, Ki Man, Jang, Seung Hyun, Lee, Chang Hee, Min, Hyun Sik, Baik, Jin Serk
• Primary Examiner(s): Tran; Dzung D
• Application Number:
  US11/166,362
• Publication Number:
  US 20060002706A1
• Time in Patent Office: 2,097 Days
• Field of Search: 398 66- 72, 398 75- 79
• US Class Current: 398/72
• 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 14/0282 WDM tree architectures
• CPC Class Codes: H04L 12/2801 Broadband local area networks

Abstract

The present invention relates to a passive optical network, which inexpensively improves the spectral efficiency of an access network and is capable of increasing the number of subscribers per channel by using WDM in combination with Time Division Multiplexing (TDM) or SubCarrier Multiple Access (SCMA) to expand a conventional WDM passive optical network. The passive optical network includes light providing means provided in a central office to provide broadband incoherent light; a multiplexer connected to the central office via an optical fiber to divide the light transmitted from the light providing means according to wavelengths and to multiplex upstream signals; a plurality of splitters to branch divided lights and to combine the upstream optical signals; and a plurality of subscribers connected to the splitters, the subscribers including wavelength-locked Fabry-Perot laser diodes capable of performing direct and analog modulation, and means for directly modulating lights of the Fabry-Perot laser diodes and transmitting modulated lights to the subscribers using time division multiplexing.

Claims

1. A passive optical network, comprising:

a broadband light source in a central office to provide broadband incoherent light;

a multiplexer connected to the central office via an optical fiber for filtering the light transmitted from the broadband light source according to wavelengths and multiplexing upstream signals to provide a first plurality of wavelengths;

at least one splitter coupled to the multiplexer for branching a wavelength of the first plurality of wavelengths and combining the upstream optical signals; and

a plurality of wavelength-locked Fabry-Perot laser diodes connected to the at least one splitter to share the branched wavelength that is injected through the splitter to determine an oscillation wavelength of the plurality of wavelength-locked Fabry-Perot laser diodes, the wavelength-locked Fabry-Perot laser diodes capable of performing direct and analog modulation, and a control unit to directly modulate lights of the Fabry-Perot laser diodes and transmitting modulated lights to subscribers using time division multiplexing.

2. The passive optical network of claim 1, wherein the central office modulates the downstream broadband incoherent light to a synchronization signal, and provides the synchronization signal to the subscribers as a reference clock.

3. The passive optical network of claim 2, wherein distances from the at least one splitter to the subscribers are kept similar to minimize guard time to set up connection between the central office and the subscribers.

4. The passive optical network of claim 1, wherein the central office and the multiplexer are connected via a single optical fiber so that bi-directional transmission is enabled.

5. A passive optical network, comprising:

a broadband light source in a central office to provide broadband incoherent light;

a multiplexer connected to the central office via an optical fiber for dividing the light transmitted from the broadband light source according to wavelengths to provide a first plurality of lights and to multiplexing upstream signals;

at least one splitter coupled to the multiplexer for branching a wavelength of the first plurality of lights and combining the upstream optical signals; and

a plurality of wavelength-locked Fabry-Perot laser diodes connected to the at least one splitter to share the branched wavelength that injected through the splitter to determine an oscillation wavelength of the plurality of wavelength-locked Fabry-Perot laser diodes, the wavelength-locked Fabry-Perot laser diodes capable of performing direct and analog modulation, and a control unit to directly modulate the Fabry-Perot laser diodes using subcarrier modulation and transmitting the modulated lights to subscribers.

6. The passive optical network of claim 5, wherein the subcarrier modulation is one of a Frequency Shift Keying (FSK), Phase Shift Keying (PSK) and Quadrature Amplifier Modulation (QAM).

7. The passive optical network of claim 5, wherein, when one or more of the subscribers do not transmit data, the light providing means lowers power of the light and thus reducing optical Beat Interference Noise (OBI), so that a number of subscribers are statically increased.

8. The passive optical network of claim 5, wherein the central office and the multiplexer are connected via a single optical fiber so that bi-directional transmission is enabled.

9. A method, comprising:

supplying broadband light;

filtering the broadband light transmitted according to wavelengths to provide a first plurality of wavelengths;

injecting, through the splitter, a filtered wavelength of the first plurality of wavelengths into a plurality of wavelength-locked Fabry-Perot laser diodes, to provide output lights, so that the injected wavelength that is shared between the plurality of wavelength-locked Fabry-Perot laser diodes through the splitter determines an oscillation wavelength of the plurality of wavelength-locked Fabry-Perot laser diodes; and

modulating the output lights of the Fabry-Perot laser diodes.

10. The method of claim 9, further comprising

multiplexing upstream signals;

and

combining the upstream signals.

11. The method of claim 9, further comprising

transmitting the modulated output lights by time division multiplexing.

12. The method of claim 9, wherein the output lights are modulated using subcarrier modulation.

13. The method of claim 9, further comprising

modulating the broadband light to provide a synchronization signal as a reference clock.

14. An apparatus, comprising:

a broadband light source to provide broadband light;

a multiplexer for filtering broadband light according to wavelengths to provide a first plurality of wavelengths;

a splitter coupled to the multiplexer to branch a wavelength of the first plurality of wavelengths; and

a plurality of wavelength-locked Fabry-Perot laser diodes connected to the splitter to share the branched wavelength that is injected through the splitter to determine an oscillation wavelength of the plurality of wavelength-locked Fabry-Perot laser diodes.

15. The apparatus of claim 14, wherein the broadband light is modulated.

16. The apparatus of claim 14, further comprising

a control unit to modulate lights of the Fabry-Perot laser diodes.

17. The apparatus of claim 16, wherein the modulated output lights are transmitted from the Fabry-Perot laser diodes by time division multiplexing.

18. The method of claim 16, wherein the modulated output lights are transmitted from the Fabry-Perot laser diodes by subcarrier modulation.

19. A system, comprising:

means for supplying broadband light;

means for filtering the broadband light according to wavelengths to provide a first plurality of wavelengths;

means for injecting, through the splitter, a filtered wavelength of the first plurality of wavelengths into a plurality of wavelength-locked Fabry-Perot laser diodes to provide output lights, so that the injected wavelength that is shared between the plurality of wavelength-locked Fabry-Perot laser diodes through the splitter determines an oscillation wavelength of the output lights; and

means for modulating the output lights of the Fabry-Perot laser diodes.

20. The system of claim 19, further comprising

means for modulating the broadband light.