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Optical transmitter, optical transmission system and modulation scheme selection method

A technology for optical transmitters and modulation schemes, which is applied in transmission systems, electromagnetic wave transmission systems, electromagnetic transmitters, etc., and can solve problems such as poor receiving sensitivity characteristics and poor dispersion tolerance characteristics

Inactive Publication Date: 2009-07-22
NEC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The optical duobinary modulation scheme has good dispersion tolerance characteristics, but poor receiving sensitivity characteristics
On the other hand, the optical DPSK modulation scheme has better receiving sensitivity characteristics, but poor dispersion tolerance characteristics

Method used

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  • Optical transmitter, optical transmission system and modulation scheme selection method
  • Optical transmitter, optical transmission system and modulation scheme selection method
  • Optical transmitter, optical transmission system and modulation scheme selection method

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Embodiment Construction

[0025] The best mode for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

[0026] (light emitter)

[0027] An optical transmitter according to an exemplary embodiment of the present invention is an optical transmitter for an optical transmission system (device). The optical transmitter in this embodiment has two modulation schemes: an optical duobinary modulation scheme and an optical DPSK modulation scheme. The optical transmitter in this embodiment is characterized in that any one of the two modulation schemes can be easily selected according to the application of each modulation scheme.

[0028] First refer to figure 1 The configuration of the light transmitter according to the embodiment of the present invention is explained. figure 1 is a block diagram showing the configuration of an optical transmitter according to an embodiment of the present invention.

[0029] Such as figure 1 As shown, the optical...

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Abstract

The present invention provides an optical transmitter, an optical transmission system and a modulation scheme selection method capable of selecting either of an optical duobinary modulation scheme and an optical DPSK modulation scheme. The optical transmitter according to the present invention includes a first exclusive OR circuit which outputs as a first output signal the exclusive OR of binary logic signals input from first and second input terminals, a delayer which delays the first output signal by a predetermined amount and outputs the delayed signal to the second input terminal, a low-pass filter which receives the first output signal as an input, converting the first output signal into a three-value signal and outputting the three-value signal as a second output signal, and a selector which selects one of the first output signal and the second output signal on the basis of a selection signal and outputs the selected signal.

Description

[0001] This application is based on and claims the benefit of priority from Japanese Patent Application No. 2008-005930 filed on January 15, 2008, the disclosure of which is incorporated herein by reference in its entirety. technical field [0002] The present invention relates to an optical transmitter used in an optical transmission system, an optical transmission system and a modulation scheme selection method. Background technique [0003] There are already optical transmitters used in optical transmission systems (devices). Regarding such an optical transmitter, depending on the application of the optical transmitter, an optical differential phase shift keying (DPSK) modulation scheme (for example, see Japanese Patent Laid-Open No. 2003-087201 and No. 2003-134181) and optical duobinary A modulation scheme (for example, see Japanese Patent Laid-Open No. 2004-135345 and No. 2005-102221 ) or the like as a modulation scheme. The optical duobinary modulation scheme has good...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B10/155H04B10/516H04B10/524H04B10/54H04B10/556H04B10/61
CPCH04B10/5561H04B10/5055H04B10/5167
Inventor 田岛勉
Owner NEC CORP
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