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    • 专利摘要:
    A system and method for optical fiber transmission (130) with mode or core shuffling. The system comprises a space-time encoder (110) and a plurality of modulators (1251, ..., 125n) respectively associated with distinct propagation modes or cores of said fiber, each modulator modulating a laser beam. Said fiber comprises a plurality of sections (1301, ..., 130L), an amplifier (140l) being provided between any two consecutive segments of the optical fiber. A mode brewer (150l) is associated with each amplifier to perform a permutation of said modes between at least two consecutive segments.
    公开号:FR3023436A1
    申请号:FR1456284
    申请日:2014-07-01
    公开日:2016-01-08
    发明作者:Elie Awwad；Othman Ghaya Rekaya-Ben；Yves Jaouen
    申请人:Telecom ParisTech；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD The present invention generally relates to the field of optical telecommunications and more particularly to those using optical fibers of multi-mode or multi-core type. BACKGROUND OF THE INVENTION STATE OF THE PRIOR ART Long-distance optical transmissions (a few hundred to a few thousand kms) use single-mode optical fibers. These have the advantage of not having any modal dispersion (apart from the polarization mode dispersion) and of being able to withstand high speeds of several tens of Gbits / s per wavelength, and this for a plurality of lengths. wave. However, for short-distance transmissions, especially for wideband local area networks (LANs), multimode or multi-core fibers are a particularly interesting alternative to single-mode fibers. Two types of multi-mode fibers can be distinguished: plastic fibers (or POF) and silica fibers. The former are generally used with simple end-of-line energy detection without multiplexing the data on the different modes. Seconds, on the other hand, generally allow propagation of only a smaller number of modes but are used with multiplexing and data detection on the different modes, which makes them interesting for ensuring high transmission capacities on both low and low modes. than long distances. The multi-mode silica fibers have a large-diameter core allowing the propagation of several guided modes, denoted L, ep for a linear polarization where est is the azimuth mode index and l'the radial mode index. The LPoi mode is the fundamental mode, the only mode that can be propagated in a single-mode fiber. The total number of L.ep modes depends on the optogeometric parameters (core diameter, index profile in particular). The information to be transmitted is distributed over the various guided modes. When the number of guided modes is low, it is called low-multi-mode optical fiber. More precisely, an optical fiber is said to be weakly multi-mode if its normalized frequency parameter V is such that V <8. The bandwidth of the multimode fibers is generally greater than that of the monomode fibers, each mode being separately modulated and the signal to be transmitted being multiplexed on the different modes. This bandwidth is however limited by the coupling between modes L, ep during the propagation (inter-mode cross-talk).
    [0002] In addition, for long distances, amplifiers must be provided between sections of optical fiber. Due to the modal dispersion of the gain of these amplifiers (as well as that due to other optical components such as multiplexers or demultiplexers for example) and, to a lesser extent due to the imperfections of the fiber (especially between splices), the different modes do not undergo the same attenuation. The loss differential between modes L, ep, also called MDL (Mode Dependent Loss), induces an increased sensitivity to noise sources, which can significantly limit the range of these systems. The multi-core fibers comprise a plurality of hearts (generally from 2 to 7 hearts) within a common sheath. The size of the cores is small enough to allow only one-mode propagation in each of them. Unlike multimode fibers, they do not exhibit modal dispersion. On the other hand, the evanescent waves create a coupling between the different cores (inter-heart crosstalk), the level of crotch is all the higher as the number of cores is high and the inter-heart distance is small. Like the inter-mode coupling discussed above, inter-core coupling limits the scope of these systems. It has been proposed in the application FR-A-2977099 in the name of the present applicant, to use a spatio-temporal coding to transmit symbols on a plurality of modes (in a weakly multi-mode fiber) or hearts. This technique makes it possible to substantially reduce the bit error rate in the case of inter-mode or inter-core cross-talk. However, for the same signal-to-noise ratio, the bit error rate remains higher than that which would be observed for a Gaussian additive channel. The object of the present invention is therefore to further reduce the bit error rate in the case of multi-mode or multi-core optical fiber transmission. DISCLOSURE OF THE INVENTION The present invention is defined by a multi-mode optical fiber transmission system comprising: an encoder, called a space-time coder, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a time of use and a mode of propagation of said fiber; a plurality of modulators respectively associated with distinct propagation modes of said fiber, each modulator modulating a laser beam during a time of use by means of a corresponding element of the matrix, each modulated laser beam being injected into said fiber to propagate in a distinct mode; wherein: said fiber comprises a plurality of sections, an amplifier being provided between any two consecutive sections for amplifying the intensity of the beams propagating in said modes; - A mode stirrer is associated with said amplifier to perform a permutation of said modes between at least two consecutive sections. The invention also relates to an optical transmission system on a multi-core fiber comprising: an encoder, called a space-time coder, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a time of use and a core of said fiber; a plurality of modulators respectively associated with cores of said fiber, each modulator modulating a laser beam during a time of use by means of a corresponding element of the matrix, each laser beam thus modulated being injected into a core distinct from said fiber; wherein: said fiber comprises a plurality of sections, an amplifier being provided between any two consecutive segments for amplifying the intensity of the beams propagating in said plurality of cores; a heart brewer is associated with said amplifier for performing a permutation of the beams of the different cores between at least two consecutive segments.
    [0003] The space-time coder can use a TAST code or a perfect code. The modulator is advantageously a QAM modulator, followed by an OFDM modulator. According to a first variant, the amplifiers are optical amplifiers. According to a second variant, the amplifiers each comprise a plurality of photodiodes for converting the optical signals of the different modes into electrical signals, elementary amplifiers amplifying the different electrical signals, and a plurality of laser diodes respectively modulated by the electrical signals thus amplified. Whatever the embodiment, it is advantageous to provide the mode / core mixers for all the Q amplifiers, the PIQ ratio being chosen so that the modal dispersion of gain of the fiber is substantially equal to the AG.VL value where L is the number of sections of the optical fiber. The invention also relates to a method of optical transmission over a multi-mode fiber comprising: a coding, called spatio-temporal coding, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a time of use and a propagation mode of said fiber; a modulation of a plurality of laser beams associated with the different modes, each laser beam being modulated during a time of use by means of an element of the corresponding matrix, each laser beam thus modulated being injected into said fiber for to propagate in a distinct mode; wherein: the intensity of the beams propagating in said modes is amplified between any two consecutive segments of said fiber; - the modes are brewed between at least two consecutive sections. Finally, the invention relates to an optical transmission method on multicore fiber comprising: a coding, said spatio-temporal coding, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a time of use and at a core of said fiber; a modulation of a plurality of laser beams associated with the different cores, each laser beam being modulated during a period of use by means of an element of the corresponding matrix, each laser beam thus modulated being injected into a core distinct from said fiber; in which: the intensity of the beams propagating along said cores is amplified between any two consecutive segments of said fiber; the beams of the different cores are brewed between at least two consecutive segments. Spatiotemporal coding can use a TAST code or a perfect code. Advantageously, the modulation comprises a first QAM modulation step followed by a second OFDM modulation step. According to a first variant, the amplification between two consecutive sections is carried out by means of optical pumping. According to a second variant, the amplification between two consecutive segments is carried out by means of an optical-electrical conversion, an amplification of the electrical signals thus obtained and an electrical-optical conversion of the electrical signals thus amplified.
    [0004] Whatever the embodiment, it is advantageous to provide P mode / core stirring steps for all Q amplification steps, the PI Q ratio being chosen so that the modal dispersion of gain of the fiber is substantially equal to the value AG .. / 7, where L is the number of sections of the optical fiber.
    [0005] BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will appear on reading preferred embodiments of the invention, with reference to the appended figures in which: FIG. 1 schematically shows a transmission system on optical fiber according to a first embodiment of the invention; Figs. 2A to 2C schematically show the variation of the bit error ratio as a function of the signal-to-noise ratio in the case of the transmission system of FIG. 1, for different levels of coupling between modes and different detection methods; Fig. 3 gives the optimal number of mode mixers per section for different modes coupling ratios; Fig. 4 schematically shows a transmission system on optical fiber according to a second embodiment of the invention.
    [0006] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS We will firstly expose the invention in the case of multi-mode optical fiber transmission, and more particularly in the case of a weakly multi-mode optical fiber. As stated in the introductory part, a multi-mode fiber is affected by a modal gain dispersion or MDL (Mode Dependent Loss) whose effects in terms of bit error rate can be fought by means of a spatio-temporal coding, the spatial variable used here being a propagation mode in the fiber.
    [0007] The basic idea of the first embodiment of the invention is to associate the spatio-temporal coding with a mixing of modes. More specifically, an optical transmission system according to this first embodiment is shown in FIG. 1. This transmission system comprises a spatio-temporal encoder 110. The symbol stream to be transmitted is divided into a block of size B, each block being transmitted during a transmission interval or TTI (rhyme Transmission Interval). The encoder associates with each block of symbols a matrix C of size Nx T, hereinafter referred to as spatio-temporal matrix: C (c (1) T 11 C1 c21 c22 C2T - - .cN1 cN2 CNTE where the elements of the matrix, cn, n = 1, ..., N, t = 1, .., T (with N 2 and T 2) are as a rule complex coefficients depending on the symbols to be transmitted, N is the number of modes used , T is an integer indicating the temporal extension of the code, that is to say the number of uses of the channel, in this case the fiber.The spatio-temporal code will advantageously be a TAST code (Threaded Algebraic Space -Time code) as described in the article by H. El Gamal et al entitled "Universal Space-Time Coding" published in IEEE Trans Information on theory, Vol 49, No. 5, May 2003. Alternatively, a The perfect code can be used as a spatio-temporal code.For a description of the perfect codes, see the article by F. Oggier et al entitled "Perfect space-time codes" published by Trans. on Information Theory, vol. 52, No. 9, September 2006. The optical transmission system comprises N lasers 120 'n = 1, ..., N, of the same wavelength or alternatively a single laser whose beam is divided into N distinct beams . In all cases, the beams are respectively modulated by the different outputs of the space-time coder. More precisely, at time t, element cn modulates the optical signal of laser 120-n by means of modulator 125-n, for example a Mach-Zehnder modulator, known per se. The modulation in question is an amplitude modulation (QAM). The types of modulation used for the different beams are not necessarily identical. Where appropriate the modulators 125-n will each comprise a first QAM modulator followed by a second OFDM modulator (not shown in the figure).
    [0008] The use of an OFDM modulation for the different modes makes it possible to overcome the modal dispersion of propagation time by choosing the size of the cyclic prefix greater than the maximum time spread spreading. In any event, the optical beams thus modulated each excite a mode of the multi-mode fiber 130. This selective excitation can be achieved either by means of an optical device in free space, or by means of an optical multiplexer. guided. The N modes used can represent all the modes of the optical fiber. This can be particularly the case when the optical fiber is weakly multimode.
    [0009] The multi-mode fiber 130 comprises a plurality L of sections, 130 e, e = 1, ..., L, an amplifier 140 e being provided between each pair of consecutive sections 130, e and 130, e + 1. The amplifier is advantageously an FMA optical amplifier (Few Mode Amplifier), adapted to simultaneously amplify the intensity of a plurality of modes of the fiber. The optical amplifier can amplify the different modes by optical pumping, for example. An example of an FMA amplifier using optical pumping in an optical fiber doped with Erbium or FM-EDFA (Few Mode Erbium Doped Fiber Amplifier) is described in the article by G. Le Coq et al. entitled "Fewmode Er3 + doped fiber with micro-structured core for multiplexing division mode in the C-band" published in Optics Express, vol. 21, No. 25 pp. 31646-31659, December 2013.
    [0010] According to a second variant, the amplifier 140, e may comprise a plurality of photodiodes for converting the optical signals of the various modes (separated by means of a diffraction grating for example) into electrical signals, elementary amplifiers amplifying the different electrical signals , and a plurality of laser diodes respectively modulated by the electrical signals thus amplified. After amplification, the electrical signals can be subject to analog-to-digital conversion, digital filtering and then digital-to-analog conversion. A plurality of digital sample streams respectively associated with the different modes is thus obtained. Whatever the variant envisaged, the amplifier may be associated with a mode mixer. In the illustrated case, a mode mixer, 150, e, is associated with each amplifier 140, e. This mode shifter performs a permutation of the plurality of modes 1, ..., N. By permutation is meant any bijection of the set of modes over itself, distinct from the identity. This permutation can be for example a circular permutation on all modes 1, ..., N. Advantageously, for each section, the permutation is a random permutation among the possible N! -1 permutations. The mode brewer can be realized by applying mechanical stresses to the fiber. An embodiment of a mode brewer can be found in the article by An Li et al. entitled "Transmission of 107-Gb / s mode and multiplexed polarization CO-OFDM signal over a two-mode fiber", published in Optics Express, April 25, 2011, vol. 19, No. 9, pp. 8808-8814. Other types of mode mixers are available on the market, for example the Space Division Multiplexing (SDM) mode brewers from Phoenix Photonics. It is important to note that when the amplifier is implemented according to the second variant mentioned above, the mixing of modes can be achieved simply by stirring the digital sample flows relating to the different modes. Thus, the mode brewer can be realized either optically or digitally (and more generally electrical by stirring the electrical signals relating to different modes). At the output of the optical fiber, on the side of the receiver (not shown), the different modes are spatially demultiplexed, converted into electrical signals by photodetectors and digitized. The digitized signals can be expressed in the following matrix form: LKY = HC + N = 11 reGII (17k) C + N (2) k = 1 where Y is a matrix of size NxT representing the T signals received on the N modes during the T tans of transmission of a TTI interval, H is a matrix of size NxN representative of the transmission channel, C is the size matrix NxT of the space-time code, and N is a matrix of size NxT whose elements are noise samples (assumed Gaussian additive white) affecting the signals received on the N modes for the transmission instants, 1 and Ge are respectively the permutation matrix of the mode mixer 150e and the gain matrix of the amplifier 140, e for the different modes. In other words, G, e is a diagonal matrix of size NxN whose elements give the respective gains of the amplifier for the different modes. The matrix G, e can be represented by the product of a mean gain (scalar) with an offset matrix around this gain. Each fiber section can be conceptually divided into K consecutive sections, the characteristics of the fiber being stationary along the length of each section and modeled by a matrix product TÆkRÆkoù R, ek, of size NxN, is the coupling matrix between modes, relative at the section k of the section L, and T, ek is a diagonal matrix, also of size NxN, whose diagonal elements give the respective phase displacements of the different modes on the section k of the section L. The matrix 1: t, ek is assumed be an orthogonal random matrix (R, ek.R, eTk = Ili where II / is the identity matrix), which reflects the conservation of distributed energy on the different modes. The non-diagonal coefficients of the coupling matrix are the coupling coefficients between modes. Their values depend on the overlapping integrals of the field distributions between the different modes propagating in the section of the section in question. The overlapping integrals themselves depend on the imperfections and the curvature of the fiber section in this section.
    [0011] The matrix Te k is, for its part, a matrix whose diagonal coefficients are of the form eek where I 9, k is the result of the drawing of a random variable uniformly distributed on [0.24. The received signals can be decoded using a maximum likelihood decoder, also called ML (Maximum Likelihood) decoder, in a manner known per se and recalled below: The maximum likelihood decoder estimates the code word CML minimizing the Euclidean distance over the set S1 of the possible codewords: CML = argminY-HC112 (3) Cen This search for the minimum supposes to know beforehand the matrix H representative of the transmission channel. This can be determined by channel estimation from pilot symbols.
    [0012] The ML decoder by exhaustive search in all, however, is complex. More precisely, its complexity varies according to card (n) = qNT where q is the cardinal of the modulation alphabet. Thus for a 6x6 TAST code using 4-QAM symbols, the cardinal of the set of codes is card (n), 436. Alternatively, a decoder based on the criterion ML may be used but does not require an exhaustive search, such as a sphere decoder or even a stack sphere decoder, also known as Sphere-Bound Stock Decoder (or SB-Stack Decoder), as described in the article by R. Ouertani et al. entitled "The spherical bound stack decoder" published in IEEE Inn Conf. on WiMob, Avignon, France, October 2008 or in the application FR-A-2930861 incorporated by reference. Alternatively again, it will be possible to use a decoder of the ZF-DFE type (Zero Forcing Decision Feedback Equalizer), known per se. This decoder is substantially simpler than the ML decoder but gives very good results. For this purpose, the expression (1) can be converted into the following vectorized expression: Y1 = 111C1-FN1-He, S + N1 (4) where Y ', N' are vectors of size N7'x1 obtained by concatenation of the column vectors of the matrices Y and N, respectively. The matrix H 'is a block matrix of size NTxNT obtained by replication of the matrix H, T times in the horizontal direction and T times in the vertical direction. It is a vector of size N7'x1 obtained by C '= I'S where I' is the generator matrix of the code, of size NTxNT and S is the vector of size NTx1 of the modulation symbols. The matrix is defined by Heq = H'I 'and is called the equivalent matrix of the transmission channel. The equivalent matrix Heq can be decomposed using a QR decomposition, ie Heq = QR where Q is a unitary matrix and R is an upper triangular matrix. ZF-DFE decoding involves solving the system equivalent to (4): i . = QH y = Rs + QHNI (5) The SZFDFE vector is obtained by solving the -L7- = RS ZFDFE system starting with the last component and taking a hard decision on the corresponding symbol. The symbol obtained by hard decision is then injected into the previous equation to obtain the previous component. This is done step by step to obtain an estimate of the different symbols transmitted.
    [0013] Fig. 2A represents the variation of the bit error rate as a function of the signal-to-noise ratio for a high coupling between modes. Fig. 2B represents the variation of the bit error rate as a function of the signal-to-noise ratio for an average coupling between modes. Finally, FIG. 2C represents the variation of the bit error ratio as a function of the signal-to-noise ratio for a weak coupling between modes.
    [0014] It was assumed that 6 modes propagated in the fiber (LP1, LP11a, LP11b, LP02, LP21a, LP21b where the indices a, b translate the anisotropy along two orthogonal axes). The gain was assumed to be equal to 1 for the LP01 mode and the gain offsets AGoi, (per amplification stage) of the LP '' modes were assumed equal to AGoi_ii = -1.3dB, AG01-02 0.2dB, and AGo1_21 = -2dB. Different scenarios are shown in Figs. 2A-2C. Scenario 210 represents the case of the classical Gaussian additive channel. The scenario 220 represents the case of a transmission in the absence of spatio-temporal coding but with mode shuffling and ML decoding in reception. The scenario 230 represents the case of a transmission in the absence of spatio-temporal coding and mode shuffling, but with ML decoding in reception. The scenario 240 represents a transmission with spatio-temporal coding using a 6x6 TAST code, with mode switching and ZF-DFE decoding on reception. The scenario 250 represents a transmission with spatio-temporal coding by means of a 6x6 TAST code, without shuffling of modes and with a ZF-DFE decoding on reception. Scenario 260 corresponds to the case of transmission in the absence of space-time coding but with mode switching and ZF-DFE decoding on reception. The scenario 270 corresponds to the case of a transmission without spatio-temporal coding or mixing of modes but with ZF-DFE decoding on reception. Finally, the scenario 280 corresponds to the case of a transmission with spatio-temporal coding by means of a 6x6 TAST code, mode switching and ML decoding on reception. Note that, whatever the coupling level, the best result is obtained when combining spatio-temporal coding (in this case a 6x6 TAST code), mixing modes and ML decoding (curves 280 in FIGS. 2A-2C). The combination of spatio-temporal coding, mode shuffling and ZF-DFE decoding also leads to a significant reduction in the bit error rate compared to the same scenario without shuffling, when the coupling level in the fiber is medium or low. The embodiment shown in FIG. 1 associates with each amplifier a mode mixer. It will be understood, however, that a mode combiner may only be associated with certain amplifiers, for example that an amplifier on Q successive amplifiers, or more generally P (P 1) mode stirrups may be provided for Q successive amplifiers, an equipment ratio of r-P1Q. This ratio will be chosen even lower as the coupling between modes will be higher and the distribution of the gain offset (amplifiers) will be narrower. In fact, both the coupling between modes in the fiber and the mixing of modes contribute to the reduction of the modal dispersion of gain in the optical fiber. In an optical fiber without coupling or shuffling, the modal dispersion of gain varies in AG.L where AG is the maximum gain offset of the amplifiers for the different modes and L is the number of sections of the fiber. Conversely, in the theoretical situation where the coupling would be maximal, that is to say in the case where the coupling matrix of a section would be a random orthogonal matrix, it can be shown that the modal dispersion of gain reaches a minimum substantially equal to AG .. / 7,. The introduction of stirrers with a rate r makes it possible to approach the modal dispersion of minimum gain.
    [0015] Fig. 3 gives the amplifiers equipment rate for amplifiers to obtain a minimum gain mode dispersion. The ordinate represents the r equipment rate brewers amplifiers and abscissa the number L of sections. Each section is assumed to consist of K = 400 sections with section coupling ratios equivalent to those generated by maximum misalignments of cores between consecutive sections equal to a fraction x% of the core radius. These misalignments represent imperfections of the fiber and generate a coupling between modes. The maximum gain offset per amplification stage was AG = 2dB. It is noted in the figure that beyond a certain number of sections, the equipment rate to obtain the minimum gain mode dispersion tends to a minimum rate. Thus, for example, for a core misalignment of 4%, it is possible to obtain the minimum modal dispersion of gain by equipping a brewer with an amplifier out of 4, since the fiber comprises more than 16 sections.
    [0016] In general, from the maximum gain offset and the inter-mode coupling rate, the optimal equipment rate of the amplifiers can be determined. This rate is optimal in the sense that, on the one hand, it makes it possible to achieve the modal dispersion of minimum gain and, on the other hand, the addition of additional brewers would not lead to an improvement in performance in terms of bit error rate. Fig. 4 schematically shows a transmission system on optical fiber according to a second embodiment of the invention. Unlike the first embodiment, the fiber used here is of multi-core type. The optical transmission system comprises a spatio-temporal encoder 410, identical to the spatio-temporal encoder 110, N lasers 420 'n = 1, ..., N, of the same wavelength or alternatively a single laser whose beam is divided into N distinct beams. The beams are respectively modulated by the different outputs of the space-time coder by means of the modulators 425 'n = 1, ..., N. The optical beams thus modulated are respectively injected into the different cores of the fiber. This injection can be performed either by means of an optical device in free space, or by means of a guided optical multiplexer. The multi-core fiber 430 comprises a plurality of sections L, 430.e, e = L, an amplifier 440k being provided between each pair of consecutive sections 430e and 430.e + 1. Each amplifier 440.e is associated with a heartbeater, 450.e, located upstream or downstream of the amplifier. The different variants described in connection with the first embodiment are also applicable here. In particular, the amplifier may be an optical amplifier or include photodiodes and amplifiers followed by laser diodes. In the same way the heart brewers can be implemented optically or numerically (and more generally electrical). Those skilled in the art will understand that the different types of decoding evoked for the first embodiment apply in the same way to the second embodiment.
    权利要求:
    Claims (16)
    [0001]
    REVENDICATIONS1. Optical transmission system on multi-mode fiber comprising: an encoder (110), said space-time coder, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a usage time and a propagation mode of said fiber; a plurality of modulators (125) respectively associated with distinct propagation modes of said fiber, each modulator modulating a laser beam during a time of use by means of a corresponding element of the matrix, each laser beam thus modulated being injected into said fiber to propagate therein in a distinct fashion; said transmission system being characterized in that: - said fiber comprises a plurality of sections (130.e), an amplifier (140 L) being provided between any two consecutive sections for amplifying the intensity of the beams propagating in said modes; - A mode stirrer (150.e) is associated with said amplifier to perform a permutation of said modes between at least two consecutive sections.
    [0002]
    2. An optical transmission system on a multi-core fiber comprising: an encoder (410), said space-time coder, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a time delay; use and at a core of said fiber; a plurality of modulators (425) respectively associated with cores of said fiber, each modulator modulating a laser beam during a period of use by means of a corresponding element of the matrix, each laser beam thus modulated being injected into a distinct heart of said fiber; said transmission system being characterized in that: - said fiber comprises a plurality of sections (430, e), an amplifier (440f) being provided between any two consecutive sections for amplifying the intensity of the beams propagating in said plurality of cores ; - A heart brewer (450, e) is associated with said amplifier to perform a permutation beams of different hearts between at least two consecutive sections.
    [0003]
    Optical transmission system according to claim 1 or 2, characterized in that the space-time coder uses a TAST code.
    [0004]
    4. Optical transmission system according to claim 1 or 2, characterized in that the space-time coder uses a perfect code.
    [0005]
    5. Optical transmission system according to one of the preceding claims, characterized in that each modulator is a QAM modulator, followed by an OFDM modulator.
    [0006]
    Optical transmission system according to one of the preceding claims, characterized in that the amplifiers are optical amplifiers. 20
    [0007]
    7. Optical transmission system according to one of claims 1 to 5, characterized in that the amplifiers each comprise a plurality of photodiodes for converting the optical signals of the different modes into electrical signals, elementary amplifiers amplifying the different electrical signals, and a plurality of laser diodes respectively modulated by the electrical signals thus amplified.
    [0008]
    8. Transmission system according to one of the preceding claims, characterized in that the mode / core mixers are provided for all Q 30 amplifiers, the P / Q ratio being chosen so that the modal dispersion of gain fiber is substantially equal to the value AG..Nii where L is the number of sections of the optical fiber.
    [0009]
    9. Optical transmission method on multi-mode fiber comprising: a coding, said spatio-temporal coding, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a usage time and a propagation mode of said fiber; a modulation of a plurality of laser beams associated with the different modes, each laser beam being modulated during a time of use by means of an element of the corresponding matrix, each laser beam thus modulated being injected into said fiber for to propagate in a distinct mode; said transmission method being characterized in that: the intensity of the beams propagating in said modes is amplified between any two consecutive segments of said fiber; - the modes are brewed between at least two consecutive sections.
    [0010]
    10. An optical transmission method on a multi-core fiber comprising: a coding, called spatio-temporal coding, transforming each block of symbols to be transmitted into a code matrix, each element of said matrix being relative to a usage time and at a core of said fiber; a modulation of a plurality of laser beams associated with the different cores, each laser beam being modulated during a period of use by means of an element of the corresponding matrix, each laser beam thus modulated being injected into a core distinct from said fiber; said transmission method being characterized in that: the intensity of the beams propagating along said cores is amplified between any two consecutive segments of said fiber; the beams of the different hearts are brewed between at least two consecutive sections.
    [0011]
    11. Optical transmission method according to claim 9 or 10, characterized in that the spatio-temporal coding uses a TAST code.
    [0012]
    12. Optical transmission method according to claim 9 or 10, characterized in that the spatio-temporal coding uses a perfect code.
    [0013]
    13. Optical transmission method according to one of claims 9 to 12, characterized in that the modulation comprises a first QAM modulation step followed by a second OFDM modulation step.
    [0014]
    14. Optical transmission method according to one of claims 9 to 13, characterized in that the amplification between two consecutive sections is performed by means of optical pumping.
    [0015]
    15. Optical transmission method according to one of claims 9 to 13, characterized in that the amplification between two consecutive sections is performed by means of an optical-electrical conversion, an amplification of the electrical signals thus obtained and an electrical conversion. -optic electrical signals and amplified.
    [0016]
    16. An optical transmission method according to one of claims 9 to 15, characterized in that P mode / heart stirring steps are provided for all Q amplification steps, the P / Q ratio being chosen so that the modal dispersion of gain of the fiber is substantially equal to the value AGJL where L is the number of sections of the optical fiber.
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    同族专利:
    公开号 | 公开日
    CN107005308B|2020-11-06|
    EP3164951B1|2021-03-17|
    US10491300B2|2019-11-26|
    FR3023436B1|2016-08-19|
    EP3164951A1|2017-05-10|
    WO2016001078A1|2016-01-07|
    KR102043220B1|2019-12-02|
    KR20170115032A|2017-10-16|
    CN107005308A|2017-08-01|
    US20170195052A1|2017-07-06|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1456284A|FR3023436B1|2014-07-01|2014-07-01|METHOD AND SYSTEM FOR TRANSMITTING OPTICAL FIBER WITH BREWING OF MODES AND / OR HEARTS|FR1456284A| FR3023436B1|2014-07-01|2014-07-01|METHOD AND SYSTEM FOR TRANSMITTING OPTICAL FIBER WITH BREWING OF MODES AND / OR HEARTS|
    KR1020177000102A| KR102043220B1|2014-07-01|2015-06-26|Method and system for transmission over optical fiber with mode and/or core scrambling|
    US15/322,612| US10491300B2|2014-07-01|2015-06-26|Method and system of optical fibre with switching of modes and/or cores|
    CN201580036322.4A| CN107005308B|2014-07-01|2015-06-26|Method and system for transmission over optical fiber with mode and/or core scrambling|
    EP15732640.6A| EP3164951B1|2014-07-01|2015-06-26|Method and system of optical fibre transmission with switching of modes and/or cores|
    PCT/EP2015/064499| WO2016001078A1|2014-07-01|2015-06-26|Method and system of optical fibre transmission with switching of modes and/or cores|
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