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Modulation scheme with increased number of states of polarization

A technology of polarization state and modulation method, which is applied in the field of optical communication and can solve problems such as work and low symbol rate

Inactive Publication Date: 2009-10-14
ALCATEL LUCENT SAS
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] When using existing optical fiber infrastructure to transmit high data rates (such as 40Gb / s, 100Gb / s or higher) and across With long transmission spans (e.g. hundreds of km or 1000 km), the system is still operating at the limit of its sensitivity despite the use of coherent detection for lower symbol rates and powerful electronic equalization

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  • Modulation scheme with increased number of states of polarization
  • Modulation scheme with increased number of states of polarization

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Embodiment Construction

[0066] Figure 1-Figure 3 This has been discussed above. Figure 4 A constellation diagram of a POL-QAM 6 / 4 modulation scheme as an exemplary embodiment of the modulation scheme of the present invention is shown. 4 SOPs each with 4 phase constellation points except in case of PDM-QPSK (see image 3 ), in POL-QAM 6 / 4, two additional polarization states are added (see Figure 4 SOP5 and SOP6 in ), which do not lie in the plane defined by SOP1-SOP4. Therefore, POL-QAM 6 / 4 uses 6 SOPs each with 4 IQ-constellation points. Here, 0° (TE) and 90° (TM) linear polarization states are used as additional polarization states. However, the SOP1-6 ensemble can be rotated on the sphere such that the relative distance between polarization states remains the same. For example, when the two polarization components forming a POL-QAM 6 / 4 signal exhibit a phase offset ψ from each other, SOP1-4 revolves around figure 2 The S1 axis in is rotated (rotation 2ψ).

[0067] The joint PDM-QPSK symb...

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Abstract

A modulation method for optical communication comprises the step of generating an optical signal modulated between a plurality of different states of polarization and between different phase states. The plurality of states of polarization comprises first states of polarization (SOP1-4). The first states of polarization (SOP1-4) define a single great circle (10) on the Poincare sphere. The method is characterized in that the plurality of states of polarization further comprise one or more second states of polarization (SOP5-6) located outside the great circle (10). Such additional second statesof polarization increase the symbol alphabet.

Description

technical field [0001] The present invention relates to optical communications and in particular to modulation schemes for optical communications in which an optical signal is modulated between different polarization states. Background technique [0002] The state-of-the-art optical transmission scheme of polarization multiplexing (PDM) using two independently phase-modulated signals, such as two QPSK (Quadrature Phase Shift Keying) signals, has higher the spectral efficiency. In a coherent receiver, such PDM signals can be polarization demultiplexed and distortion compensated by means of digital signal processing. [0003] figure 1 A conventional PDM-QPSK transmitter is shown. The transmitter includes a laser that generates an optical carrier signal. The optical carrier signal is split and fed to an upper IQ modulator 2a and a lower IQ modulator 2b. The IQ modulator 2a above is used for the first polarization component ( figure 1 Denoted as "x" in), such as the TE com...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B10/145H04B10/155H04B10/50H04B10/532H04B10/556
CPCH04B10/548H04L27/2096H04B10/505H04L5/0014H04L5/12H04L27/3416H04B10/532H04L5/04H04B10/5561H04L27/2085H04J14/06
Inventor H·比洛
Owner ALCATEL LUCENT SAS
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