SPATIAL DOMAIN BASED MULTI DIMENSIONAL CODED MODULATION FOR MULTI TB PER SECOND SERIAL OPTICAL TRANSPORT NETWORKS

• US 20120207470A1
• Filed: 10/10/2011
• Published: 08/16/2012
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Djordjevic, Ivan B., Xu, Lei, Wang, Ting
• Granted Patent: US 8,977,121 B2
• Time in Patent Office: Days
• US Class Current: 398/44
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/291 in which processing or amplification is carried out without conversion of the main signal from optical form
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0278 WDM optical network architectures
• CPC Class Codes: H04J 14/04 Mode multiplex systems
• CPC Class Codes: H04J 14/06 Polarisation multiplex systems

Abstract

An optical transport network based on multimode/multicore fibers includes a mode-multiplexer to multiplex independent data streams from one or more transmitters; a multimode erbium-doped fiber amplifier (MM EDFA) to compensate for MMF loss; a multimode optical add-drop multiplexer (MM OADM) to add and/or drop multimode channels in multimode networks; a multimode optical cross-connect; and a mode-demultiplexer to separate various mode streams to one or more receivers.

Claims

1. An optical transport network, comprising:

a. a mode multiplexer to combine inputs from one or more transmitters;

b. a multimode erbium-doped fiber amplifier (MMEDFA) to compensate for multimode fiber loss;

c. a multimode optical add-drop multiplexer (MMOADM) to add and/or drop multimode signals;

d. a multimode optical cross-connect; and

e. a mode demultiplexer to separate the mode-multiplexed streams and provide data to one or more receivers.

2. The network of claim 1, comprising a spatial-domain-based N-dimensional modulator.

3. The network of claim 2, comprising one electro-optical modulator (EO MOD) per coordinate coupled to a mode-multiplexer.

4. The network of claim 3, wherein the mode-multiplexer comprises a taper core receiving a plurality of channels.

5. The network of claim 4, wherein the taper core is coupled to a multimode fiber (MMF).

6. The network of claim 2, comprising a power splitter coupled to the EO MOD.

7. The network of claim 1, comprising a passive MM device coupled to an MMF.

8. The network of claim 7, wherein the passive MM device comprises a mode splitter coupled to a plurality of single mode devices, each of the single mode devices coupled to a mode combiner.

9. The network of claim 1, wherein the MM EDFA comprises a spatial mode WDM combiner receiving a multimode weak incoming signal and driving a multimode erbium doped fiber.

10. The network of claim 9, wherein corresponding laser pumps are independently adjusted so that different spatial-modes have the same output power level.

11. The network of claim 1, wherein K input bits are used as an address in a look-up table in which N-dimensional coordinates are stored and, after selection, used as inputs to the mode-multiplexer by EO MODS.

12. The network of claim 1, wherein orthogonal demultiplexed modes are used as inputs to a corresponding set of N photodetectors/receivers.

13. The network of claim 1, comprising a donut-shaped photodetector to simultaneously detect all separate OAM modes of interest.

14. The network of claim 1, wherein a center frequency of the bands within one band-group are orthogonal to each other to simplify the band detection.

15. The network of claim 1, comprising a three-layer architecture with a baseband layer, a mode multiplexing layer where several orthogonal OAM modes are used to multiplex corresponding data streams, and a photonic layer.

16. The network of claim 15, wherein the baseband layer comprises a coded modulation block coupled to DACs and low-pass filters.

17. The network of claim 15, wherein the photonic layer combines signals from several-frequency locked lasers into a serial optical transport signal.

18. The network of claim 1, comprising multimode fiber (MMF), multiplexers/demultiplexers, MMF amplifiers, MM optical add-drop multiplexers, MM cross-connects and modes-detector.

19. A method to communicate over an optical transport network, comprising:

splitting a spatial-mode signal using a modes-demultiplexer;

processing each mode by a corresponding single mode fiber (SMF) component, and combining SMF signals using a mode-multiplexer.

20. The method of claim 19, comprising organizing a frame into several band-groups with center frequencies being orthogonal to each other, each group carrying traffic.

21. The method of claim 19, comprising processing a spatial-domain-based multidimensional coded-modulation with N-dimensional signal constellations.

22. The method of claim 19, comprising forming N-dimensional constellations by employing orbital angular momentum (OAM) states as basis functions.

23. The method of claim 19, comprising combining quasi-cyclic binary/nonbinary LDPC codes of large girth to achieve multi-terabit per second serial optical transmission for long-haul applications.

24. The method of claim 19, comprising applying OAM states in combination with spin angular momentum (SAM) to double the dimensionality of OAM-space.

25. The method of claim 19, comprising combining a weak spatial-mode signal and corresponding pump signals in a spatial-mode WDM combiner.

26. The method of claim 25, wherein corresponding pumps are independently adjusted so that different spatial-modes have the same output power level.

27. The method of claim 19, comprising integrating in one integrated circuit a power combiner, a series of EO MODS and mode-multiplexer on a mixed-signal device;

and integrating modes-demultiplexer and series of photodetectors or donut-shape-based photodetectors on another integrated circuit.