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Coherent light receiving system

A technology of coherent light and receiver, applied in the field of optical communication system, can solve the problems of inability to receive and realize 40Gbps fast signal light, and achieve the effect of simplified structure and size reduction

Inactive Publication Date: 2012-03-28
FUJITSU LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, a coherent optical receiving system has a fundamental problem that reception cannot be performed when the polarization state of the local oscillator light output from the local oscillator light source provided for the optical receiver is orthogonal to the polarization state of the received signal light
[0019] Therefore, the conventional coherent optical receiver in the system (III) needs a circuit whose bandwidth is three times or more (that is, 120Gbps or more) of the signal bandwidth of the signal light of 40Gbps, and cannot realize the fast signal light of 40Gbps or more.

Method used

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no. 1 approach

[0045] figure 1 A coherent optical receiver 10 according to the first embodiment is shown. figure 1 The coherent optical receiver 10 shown in can be applied as image 3 An optical receiver 306 in an optical communication system 300 is shown in FIG. here, in image 3 In the optical communication system 300 shown, a WDM transmitting device 301 is connected to a WDM receiving device 302 via an optical network 310 .

[0046] The wavelength division multiplexing transmission device 301 includes: a plurality of optical transmitters (T) 303 outputting optical signals having different wavelengths; and a wavelength multiplexer 304 . The optical transmitter 303 modulates light using multi-valued phase modulation such as DQPSK, QPSK, and QAM (Quadrature Amplitude Modulation), and outputs the modulated light as an optical signal. The wavelength multiplexer 304 multiplexes the optical signal from the optical transmitter 303 in the wavelength domain, and transmits the multiplexed ligh...

no. 2 approach

[0090] Figure 6 is a block diagram showing a coherent optical receiver 10A according to the second embodiment of the present invention. Figure 6 The coherent optical receiver 10A shown in can be applied as image 3 is shown in the receiver 306, and includes a Figure 15 The coherent optical receiver shown in (see reference number 200) modulates the local optical generator 11 differently.

[0091] refer to Figure 6 , a coherent optical receiver 10A includes: an identification circuit 7; a VCO 8a; and a frequency divider 9, which are basically the same as those according to the first embodiment. In addition, the coherent optical receiver 10A also includes: a modulated local light generator (LL GEN) 11; a 2×4 phase mixing circuit 12 as an optical mixer; a differential photodetector (D-PD) 13- 1 and 13-2; ADCs 14-1 and 14-2; digital signal processor 15; and repeating pattern generator 8e.

[0092] The modulated local light generator 11 outputs the local oscillator light for...

no. 3 approach

[0193] Figure 12 is a block diagram showing a coherent optical receiver 10B according to the third embodiment of the present invention. Figure 12 The coherent optical receiver 10B shown in can be used as image 3 The optical receiver 306 in. Here, the coherent optical receiver 10B according to the third embodiment includes a polarization modulator (POL-MOD) 11A for polarization modulation (see Figure 7 , 10 or 11) to replace the polarization controller 20 in the structure of the coherent optical receiver 10 according to the first embodiment.

[0194] here, Figure 12 The coherent optical receiver 10B shown in , LO1 and the phase modulator 2 form a first modulated light output unit for outputting light modulated with an optical frequency based on a second clock phase-synchronized with the first clock (local oscillator modulating light). By setting the received signal light as m-value modulated light (mPSK, mQAM, etc.) with a transmission bit rate of X[Gb / s] (the symbol...

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Abstract

The invention provides a coherent light receiving system. In order to reduce the size and simplify the structure of a coherent light receiver, the coherent light receiver includes an optical mixer for coupling local oscillator light and reception signal light, a photoelectric converter for photoelectrically converting light coupled in the optical mixer, a reception data processing unit for extracting reception data included in the reception signal light through digital signal processing for processing the coupled signal converted into an electrical signal by the photoelectric converter, basedon a first clock, and a modulator for modulating the local oscillator light or the reception signal light inputted to the optical mixer respectively, by using a clock phase-synchronized with the first clock used for the digital signal processing in the reception data processing unit.

Description

technical field [0001] The invention relates to an optical receiver used in an optical transmission system, in particular to an optical receiver of a coherent optical receiving system independent of the polarization state of signal light and an optical communication system. Background technique [0002] In order to realize ultra-fast optical transmission systems of 40Gbps or more, optical receiver-transmitters based on multi-valued phase modulation such as RZ-DQPSK (Return to Zero Differential Quadrature Phase Shift Keying) have been developed. There is a need to further improve the optical noise tolerance of optical receiver-transmitters based on multivalued phase modulation, and to reduce the optical receiver-transmitter the size of. As a means of realizing it, coherent light receiving systems preferably include, for example, homodyne (homodyne) systems, intradyne (intradyne) systems, and heterodyne (heterodyne) systems, and their applications have been studied (for examp...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B10/148H04B10/516H04B10/275H04B10/291H04B10/40H04B10/50H04B10/532H04B10/54H04B10/556H04B10/58H04B10/60H04B10/61H04J14/00H04J14/02
CPCH04B10/6151H04B10/611H04B10/614H04B10/6165H04B10/60H04B10/61H04B10/65
Inventor 星田刚司
Owner FUJITSU LTD