CN101557270A - Full-optical Fourier converter, inverse converter and orthogonal frequency division multiplexing system - Google Patents

Abstract

A full-optical Fourier converter, an inverse converter and an orthogonal frequency division multiplexing system belong to optical signal processing devices and optical transmission systems and aim at realizing Fourier conversion and inverse conversion functions by a full-optical way and eliminating the dependency on processing speed of an electronic chip. The full-optical Fourier converter consists of two N/2*N/2 Fourier converters, N/2 2*2 Fourier converters and N/2 phase shifters; the only difference between the full-optical Fourier converter and the full-optical Fourier inverse converter is that the phase shifting values of the phase shifter are opposite numbers; and the orthogonal frequency division multiplexing system comprises a clock divider, a continuous light laser, an electro-optic modulator, a splitter, a serial-parallel converter, a full-optical Fourier inverse converter, an optical fiber passage, a full-optical Fourier converter, a time gate, a demodulator and a parallel-serial converter. The invention uses the full-optical way to dispose in the whole process, eliminates the dependency on the processing speed of the electronic chip and has extremely large potential in ultra-high speed fiber communication systems.

Description

Full-optical Fourier converter, inverse transformer and a kind of ofdm system

Technical field

The invention belongs to optical signal processor part and optical transmission system, be specifically related to a kind ofly realize the converter of Fourier transform and inverse transformation function, and utilize the ofdm system that their constitute in full light mode.

Background technology

Along with the development of optical fiber preparation technology, in speed fiber optic communication systems, the anti-drain performance of optical fiber obtains huge raising, the principal element that influences systematic function is not loss, but because chromatic dispersion, polarization mode dispersion, the distortion of the signal that non-linear factor etc. bring.The particularly influence that brings of chromatic dispersion makes that generally all must use dispersion compensating fiber offsets the deterioration that chromatic dispersion brings in the optical fiber telecommunications system, and this has caused the raising of system cost and complexity.In order to solve the time delay of the signal that chromatic dispersion, polarization mode dispersion etc. bring in the optical fiber telecommunications system, orthogonal frequency division multiplexi makes it have very big potentiality in speed fiber optic communication systems with its high availability of frequency spectrum with to the insensitivity of chromatic dispersion.

OFDM (Orthogonal Frequency Division Multiplexing, OFDM) be a kind of special multi-carrier modulation technology, its basic principle that transmits data is that high-speed data-flow is divided into a plurality of parallel low rate data streams, and the data stream modulates that each is such is on mutually orthogonal single carrier wave or subcarrier.Because the modulation rate on each way carrier wave greatly reduces, this has just improved the tolerance of system for chromatic dispersion greatly.

The application technology of OFDM on wireless and copper conductor is very ripe, the generation of OFDM symbol is normally done inverse fast fourier transform to the signal of telecommunication: earlier serial electric signal is converted to and horizontal electrical signal, these and horizontal electrical signal are multiplexed on a plurality of subcarriers, be mutually orthogonal between the subcarrier, carry out the fast fourier transform of the signal of telecommunication again, produce OFDM symbol waveform by optical modulator then.The signal of telecommunication is done inverse fast fourier transform and fast fourier transform adopt the inverse fourier transform chip of electricity and the Fourier transform chip of electricity respectively, they are subjected to the electronic bottleneck restriction, can not reach very two-forty.Hongchun Bao and William Shieh at " Transmission simulationof coherent optical OFDM signals in WDM systems; " (Opt.Express15,4410-4418 (2007)) provides a kind of ofdm system, this ofdm system is when carrying out transfer of data, the circuit of modulator, detector, signal processing all needs to be operated under the two-forty, device is proposed very high requirement, even be difficult to realize.

Summary of the invention

The invention provides a kind of full-optical Fourier converter, full-optical Fourier inverse transformer, a kind of ofdm system that is made of them is provided simultaneously, purpose is to realize discrete Fourier transform (DFT) and inverse transformation function in full light mode, eliminates the dependence for the electronic chip processing speed.

A kind of full-optical Fourier converter of the present invention is N * N Fourier transformer, carries out following conversion:

$X\left(k\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)e^{-\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="A20091006189600141.png,A20091006189600172.png"\; state="\{\{state\}\}">i</figure-callout>}\frac{2\mathrm{\&pi;}}{N}\mathrm{nk}},$

X in the formula (n) expression time domain data sequence, X (k) expression is through the frequency domain data sequence after the discrete Fourier transform (DFT), and N represents the number of data in the sequence; It is characterized in that:

It is by two N/2 * N/2 Fourier transformer, N/2 2 * 2 Fourier transformer and N/2 phase shifter formation, first N/2 * N/2 Fourier transformer be input as even signal α in the light signal of N road ₀, α ₂α _N-2Second N/2 * N/2 Fourier transformer be input as odd number signal alpha in the light signal of N road ₁, α ₃α _N-1The N/2 road output light signal of first N/2 * N/2 Fourier transformer is sent into first input port of N/2 2 * 2 Fourier transformers respectively; Output light signal in the N/2 road of second N/2 * N/2 Fourier transformer is through sending into second input port of individual 2 * 2 Fourier transformers of N/2 respectively after N/2 the phase shifter, the phase shift of i phase shifter is-2 Π/N * (i-1) in N/2 phase shifter; The output light signal of N/2 2 * 2 Fourier transformers is β ₀, β ₁β _N-1

Described 2 * 2 Fourier transformers are made of 2 * 2 waveguide couplers and two-Π/2 phase shifters, and two-Π/2 phase shifters are connected to the homonymy input and the output of 2 * 2 waveguide couplers;

Described phase shifter utilizes the thermo-optic effect of silica-based waveguides to realize: gold plaque is attached on the silica-based waveguides, feeds different fixed currents and phase place is transferred to-2 Π/N * (i-1);

I=1～N/2, N=2 ^m, m is the positive integer greater than 1.

A kind of full-optical Fourier inverse transformer of the present invention is N * N inverse fourier transform device, carries out following conversion:

$x\left(n\right)=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}X\left(k\right){\mathrm{<figure-callout\; id="2"\; label="e\; i"\; filenames="A20091006189600141.png,A20091006189600172.png"\; state="\{\{state\}\}">e</figure-callout>}}^i$

X in the formula (k) expression frequency domain data sequence, the time domain data sequence of x (n) expression after inverse discrete fourier transform, N represents the number of data in the sequence; It is characterized in that:

It is by two N/2 * N/2 Fourier transformer, N/2 2 * 2 Fourier transformer and N/2 phase shifter formation, first N/2 * N/2 Fourier transformer be input as even signal α in the light signal of N road ₀, α ₂α _N-2Second N/2 * N/2 Fourier transformer be input as odd number signal alpha in the light signal of N road ₁, α ₃α _N-1The N/2 road output light signal of first N/2 * N/2 Fourier transformer is sent into first input port of N/2 2 * 2 Fourier transformers respectively; Output light signal in the N/2 road of second N/2 * N/2 Fourier transformer is through sending into second input port of individual 2 * 2 Fourier transformers of N/2 respectively after N/2 the phase shifter, the phase shift of i phase shifter is 2 Π/N * (i-1) in N/2 phase shifter; The output light signal of N/2 2 * 2 Fourier transformers is β ₀, β ₁β _N-1

Described 2 * 2 Fourier transformers are made of 2 * 2 waveguide couplers and two Π/2 phase shifters, and two Π/2 phase shifters are connected to the homonymy input and the output of 2 * 2 waveguide couplers;

Described phase shifter utilizes the thermo-optic effect of silica-based waveguides to realize: gold plaque is attached on the silica-based waveguides, feeds different fixed currents phase place is transferred to 2 Π/N * (i-1);

I=1～N/2, N=2 ^m, m is the positive integer greater than 1.

A kind of full optical Orthogonal Frequency Division Multiplexing system of the present invention comprises: continuous light laser, electrooptic modulator, splitter, deserializer, inverse fourier transform device, optical-fibre channel, Fourier transformer, demodulator, parallel-to-serial converter; It is characterized in that:

Described inverse fourier transform device and Fourier transformer are respectively full-optical Fourier inverse transformer, full-optical Fourier converter;

Clock dividers takes out clock signal from initial data to be sent, and doubly with its cycle expansion N, be used for controlling deserializer and drive electrooptic modulator, the continuous light that electrooptic modulator is sent into the continuous light laser is modulated, the formation cycle is an initial data cycle N light pulse sequence doubly, send into splitter, be divided into the identical light pulse sequence in N road; Initial data is sent into deserializer, deserializer is gone here and there under the control of Clock dividers output signal and is changed, form the N channel parallel data, send into N electrooptic modulator respectively and carry out intensity modulated, light signal after the modulation also is advanced into the full-optical Fourier inverse transformer, the full-optical Fourier inverse transformer forms the mutually orthogonal N way carrier wave of frequency spectrum after with their conversion, and this N way carrier wave is coupled, and sends in the optical-fibre channel and transmits;

The light signal of optical-fibre channel output is sent into the full-optical Fourier converter, by conversion, light signal is divided into N way carrier wave, this N way carrier wave enters N demodulator respectively under the control of time gate, recover the N road signal of telecommunication, and be advanced into parallel-to-serial converter recovery initial data; N=2 ^m, m is the positive integer greater than 1.

Described full optical Orthogonal Frequency Division Multiplexing system is characterized in that:

Described time gate comprises clock signal maker and electrooptical switching, the on off state of clock signal maker control electrooptical switching, and the clock signal that the clock signal maker generates, the clock cycle is the 1/N in initial data synchronised clock cycle; The duty ratio of clock signal equals 1/N, and N is a sub-carrier number.

Among the present invention, OFDM and the de-multiplex operation of light signal after ovennodulation is that mode by full light realizes, promptly the light signal that comes out from electrooptic modulator all is to handle in the mode of full light up to the whole process of demodulator, eliminated the dependence of system, very big potentiality have been arranged in the ultrahigh speed optical fiber telecommunications system for the electronic chip processing speed.

Description of drawings

Fig. 1 is the structural representation of N * N Fourier transformer;

Fig. 2 is the structural representation of 2 * 2 Fourier transformers;

Fig. 3 is the structural representation of 2 * 2 waveguide coupler sandwich layers;

Fig. 4 is an ofdm system structural representation of the present invention;

Fig. 5 is the time gate structural representation;

Fig. 6 is the sub-carrier signal schematic diagram after the receiving terminal time-delay.

Embodiment

The present invention is further described below in conjunction with accompanying drawing.

As shown in Figure 1, N * N Fourier transformer is by two N/2 * N/2 Fourier transformer 3, N/2 2 * 2 Fourier transformer 2 and N/2 phase shifter formation, first N/2 * N/2 Fourier transformer be input as even signal α in the light signal of N road ₀, α ₂α _N-2Second N/2 * N/2 Fourier transformer be input as odd number signal alpha in the light signal of N road ₁, α ₃α _N-1The N/2 road output light signal of first N/2 * N/2 Fourier transformer is sent into first input port of N/2 2 * 2 Fourier transformers respectively; Output light signal in the N/2 road of second N/2 * N/2 Fourier transformer is through sending into second input port of individual 2 * 2 Fourier transformers of N/2 respectively after N/2 the phase shifter, the phase shift of i phase shifter is-2 Π/N * (i-1) in N/2 phase shifter; The output light signal of N/2 2 * 2 Fourier transformers is β ₀, β ₁β _N-1I=1～N/2, N=2 ^m, m is the positive integer greater than 1;

As shown in Figure 2,2 * 2 Fourier transformers are made of 2 * 2 waveguide couplers 1 and two-Π/2 phase shifters, and two-Π/2 phase shifters are connected to the homonymy input and the output of 2 * 2 waveguide couplers;

The transfer function of 2 * 2 waveguide couplers can be expressed as:

$\left[\begin{array}{c}{\mathrm{\&beta;}}_0\\ {\mathrm{\&beta;}}_1\end{array}\right]=\frac{1}{\sqrt{2}}\left[\begin{array}{cc}1& \mathrm{<figure-callout\; id="1"\; label="j\; j"\; filenames="A20091006189600141.png,A20091006189600172.png"\; state="\{\{state\}\}">j</figure-callout>}& \\ j& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&alpha;}}_0\\ {\mathrm{\&alpha;}}_1\end{array}\right]$

Wherein, α ₀, α ₁, β ₀, β ₁The light signal of representing 2 * 2 waveguide coupler input and output ports respectively can constitute 2 * 2 Fourier transformers in phase shift-Π/2 respectively at the homonymy input port and the output port of 2 * 2 waveguide couplers, and the relation of input and output light signal is shown below:

${\mathrm{\&beta;}}_0=\frac{1}{\sqrt{2}}({\mathrm{\&alpha;}}_0+{\mathrm{\&alpha;}}_1)$

${\mathrm{\&beta;}}_1=\frac{1}{\sqrt{2}}({\mathrm{\&alpha;}}_0-{\mathrm{\&alpha;}}_1)$

According to by 2 * 2 Fourier transformers shown in Figure 2 and shown in Figure 1 from N/2 * N/2 Fourier transformer to N * extended method of N Fourier transformer, can access any Y * Y Fourier transformer; For example, can utilize 2 * 2 Fourier transformers to expand and constitute 4 * 4 Fourier transformers; Utilize 4 * 4 Fourier transformers to expand again and constitute 8 * 8 Fourier transformers; So recursion is gone down, and can constitute any Y * Y Fourier transformer, Y=2 ^m, m is the positive integer greater than 1.

Among Fig. 2,2 * 2 waveguide couplers are the silica-based planar waveguide directional coupler of 3dB, and its input port number is 2, and the output port number is that 2. its structures are three layers, and the sandwich layer waveguide is clipped between the identical covering of two-layer refractive index, and the structure of its sandwich layer as shown in Figure 3.

Among Fig. 1 and Fig. 2, phase shifter utilizes the thermo-optic effect of silica-based waveguides to realize: gold plaque is attached on the silica-based waveguides, feeds different fixed currents and phase place is transferred to-2 Π/N * (i-1) i=1～N/2, N=2 ^m, m is the positive integer greater than 1;

Because the phase change value of each phase shifter all is constant, can be transferred to phase place the size of requirement, and need dynamic change, so the response speed of thermo-optic effect can not have influence on full light discrete Fourier transform (DFT) and inverse transformation at a high speed slowly.

For N * N inverse fourier transform device, only need get opposite number to the phase shift value of the phase shifter in N * N Fourier transformer and get final product.

Fig. 3 is the structural representation of 2 * 2 waveguide coupler sandwich layers; Thick black lines in the square frame is represented the high index waveguide of sandwich layer, and remainder is for being low-index waveguide.As an embodiment, high index waveguide is the silicon dioxide of refractive index 1.4561, and low-index waveguide and last under-clad layer are the silicon dioxide of refractive index 1.4450.

As shown in Figure 4, a kind of full optical Orthogonal Frequency Division Multiplexing system of the present invention comprises: Clock dividers 4, continuous light laser 5, electrooptic modulator 6, splitter 7, deserializer 8, full-optical Fourier inverse transformer 9, optical-fibre channel 10, full-optical Fourier converter 11, time gate 12, demodulator 13, parallel-to-serial converter 14;

As an embodiment, Clock dividers 4 adopts the DS3104 chip of Maxim Integrated Products Inc.; Continuous light laser 5 adopts the narrow linewidth laser KG-CLS-S550 of Beijing Kang Guan Electro-optical Technology, INC. (US) 62 Martin Road, Concord, Massachusetts 017; Electrooptic modulator 6 adopts the 40G intensity modulator chip of Beijing Kang Guan Electro-optical Technology, INC. (US) 62 Martin Road, Concord, Massachusetts 017; Splitter 7 adopts single window double window mouth optical fiber splitter of Shenzhen Science and Technology Ltd. of light Netcom; Deserializer 8 adopts the SN65LVDS152 chip of Texas Instruments; Demodulator 13 adopts the 10G-Receiver_rx chip of Beijing Kang Guan Electro-optical Technology, INC. (US) 62 Martin Road, Concord, Massachusetts 017; Parallel-to-serial converter 14 adopts the SN65LVDS151 chip of Texas Instruments.

Clock dividers 4 takes out clock signal from initial data to be sent, and with 8 times of its cycle expansions, be used for controlling deserializer 8 and drive electrooptic modulator 6, the continuous light that electrooptic modulator is sent into continuous light laser 5 is modulated, the formation cycle is initial data cycle 8 times a light pulse sequence, send into splitter 7, be divided into 8 tunnel identical light pulse sequences; Initial data is sent into deserializer 8, deserializer is gone here and there under the control of Clock dividers 4 output signals and is changed, form 8 channel parallel datas, send into 8 electrooptic modulators 6 respectively and carry out intensity modulated, light signal after the modulation also is advanced into full-optical Fourier inverse transformer 9, the full-optical Fourier inverse transformer forms 8 mutually orthogonal way carrier waves of frequency spectrum after with their conversion, and this 8 way carrier wave is coupled, and sends into transmission in the optical-fibre channel 10;

The light signal of optical-fibre channel 10 outputs is sent into full-optical Fourier converter 11, by conversion, light signal is divided into 8 way carrier waves, this 8 way carrier wave enters 8 demodulators 13 respectively under the control of time gate 12, recover 8 road signals of telecommunication, and be advanced into parallel-to-serial converter 14 recovery initial data.

As shown in Figure 5, time gate comprises clock signal maker 15 and electrooptical switching 16, the on off state of clock signal maker 15 control electrooptical switchinges 16, and the clock signal that the clock signal maker generates, the clock cycle is the 1/N in initial data synchronised clock cycle; The duty ratio of clock signal equals 1/N, and N is a sub-carrier number.

As an embodiment, sub-carrier number N=8; Clock signal maker 15 adopts AnalogDevices, the AD9551 chip of Inc (ADI) company; Electrooptical switching 16 adopts the high-speed optical switch chip of Beijing Kang Guan Electro-optical Technology, INC. (US) 62 Martin Road, Concord, Massachusetts 017.

The duration that electrooptical switching is opened state equals the OFDM symbol cycle divided by sub-carrier number N, and the duration of off status equals N/one that an OFDM symbol cycle deducts symbol period.

At receiving terminal, need under the control of time gate 12, carry out for the rectification of each road light signal.This be because, at receiving terminal, Fourier transformer 11 makes the N light signal experience different time-delays after the light signal demultiplexing, the time-delay length of each road light signal is calculated according to following formula:

$\mathrm{\&delta;t}\left(n\right)=n\&times;\frac{T}{N},$ In the formula, the time that δ t (n) expression n road light signal postpones, N represents sub-carrier number, and T represents the OFDM symbol cycle.

Fig. 6 has provided the sub-carrier signal schematic diagram after the receiving terminal time-delay.4 time shaft t from bottom to up represent that respectively time-delay is 0, T/4, the 4 way carrier signals of 2T/4 and 3T/4.Two adjacent OFDM symbol x of expression front and back among Fig. 5 ₀(p), x ₁(p), p=0,1,2,3, the OFDM symbol cycle is T.Only in the time period that dotted rectangle is represented, the information of carrying in the four way carrier waves just belongs to same OFDM symbol, and At All Other Times the section in, the information of carrying separately in the four way carrier waves belongs to a plurality of OFDM symbols, so can not recover initial data by them.

And to obtain frequency domain data X (k), need sue for peace to the time domain data sequence of the different phase shifts of same OFDM symbol, this just makes that in the cycle of an OFDM symbol only summation just can obtain corresponding frequency domain data X (k) to the time domain data x (n) after the phase shift in the time period (the OFDM symbol period T is divided by sub-carrier number 4) that dotted rectangle is represented.The effect of time gate is exactly to help demodulator to find this time period in the cycle at an OFDM symbol.

Claims (4)

1. a full-optical Fourier converter is N * N Fourier transformer, carries out following conversion:

$X\left(k\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)e^{-i\frac{2\mathrm{\&pi;}}{N}\mathrm{nk}},$

X in the formula (n) expression time domain data sequence, X (k) expression is through the frequency domain data sequence after the discrete Fourier transform (DFT), and N represents the number of data in the sequence; It is characterized in that:

It is by two N/2 * N/2 Fourier transformer, N/2 2 * 2 Fourier transformer and N/2 phase shifter formation, first N/2 * N/2 Fourier transformer be input as even signal α in the light signal of N road ₀, α ₂α _N-2Second N/2 * N/2 Fourier transformer be input as odd number signal alpha in the light signal of N road ₁, α ₃α _N-1The N/2 road output light signal of first N/2 * N/2 Fourier transformer is sent into first input port of N/2 2 * 2 Fourier transformers respectively; Output light signal in the N/2 road of second N/2 * N/2 Fourier transformer is through sending into second input port of individual 2 * 2 Fourier transformers of N/2 respectively after N/2 the phase shifter, the phase shift of i phase shifter is-2 П/N * (i-1) in N/2 phase shifter; The output light signal of N/2 2 * 2 Fourier transformers is β ₀, β ₁β _N-1

Described 2 * 2 Fourier transformers are made of 2 * 2 waveguide couplers and two-П/2 phase shifters, and two-П/2 phase shifters are connected to the homonymy input and the output of 2 * 2 waveguide couplers;

Described phase shifter utilizes the thermo-optic effect of silica-based waveguides to realize: gold plaque is attached on the silica-based waveguides, feeds different fixed currents and phase place is transferred to-2 П/N * (i-1);

I=1～N/2, N=2 ^m, m is the positive integer greater than 1.

2. a full-optical Fourier inverse transformer is N * N inverse fourier transform device, carries out following conversion:

$x\left(n\right)=\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}X\left(k\right)e^{i\frac{2\mathrm{\&pi;}}{N}\mathrm{nk}}$

X in the formula (k) expression frequency domain data sequence, the time domain data sequence of x (n) expression after inverse discrete fourier transform, N represents the number of data in the sequence; It is characterized in that:

It is by two N/2 * N/2 Fourier transformer, N/2 2 * 2 Fourier transformer and N/2 phase shifter formation, first N/2 * N/2 Fourier transformer be input as even signal α in the light signal of N road ₀, α ₂α _N-2Second N/2 * N/2 Fourier transformer be input as odd number signal alpha in the light signal of N road ₁, α ₃α _N-1The N/2 road output light signal of first N/2 * N/2 Fourier transformer is sent into first input port of N/2 2 * 2 Fourier transformers respectively; Output light signal in the N/2 road of second N/2 * N/2 Fourier transformer is through sending into second input port of individual 2 * 2 Fourier transformers of N/2 respectively after N/2 the phase shifter, the phase shift of i phase shifter is 2 П/N * (i-1) in N/2 phase shifter; The output light signal of N/2 2 * 2 Fourier transformers is β ₀, β ₁β _N-1

Described 2 * 2 Fourier transformers are made of 2 * 2 waveguide couplers and two П/2 phase shifters, and two П/2 phase shifters are connected to the homonymy input and the output of 2 * 2 waveguide couplers;

Described phase shifter utilizes the thermo-optic effect of silica-based waveguides to realize: gold plaque is attached on the silica-based waveguides, feeds different fixed currents phase place is transferred to 2 П/N * (i-1);

I=1～N/2, N=2 ^m, m is the positive integer greater than 1.

3. full optical Orthogonal Frequency Division Multiplexing system that constitutes by the full-optical Fourier inverse transformer of the full-optical Fourier converter of claim 1 and claim 2, comprise: the continuous light laser, electrooptic modulator, splitter, deserializer, inverse fourier transform device, optical-fibre channel, Fourier transformer, demodulator, parallel-to-serial converter; It is characterized in that:

Described inverse fourier transform device and Fourier transformer are respectively full-optical Fourier inverse transformer, full-optical Fourier converter;

Clock dividers takes out clock signal from initial data to be sent, and doubly with its cycle expansion N, be used for controlling deserializer and drive electrooptic modulator, the continuous light that electrooptic modulator is sent into the continuous light laser is modulated, the formation cycle is an initial data cycle N light pulse sequence doubly, send into splitter, be divided into the identical light pulse sequence in N road; Initial data is sent into deserializer, deserializer is gone here and there under the control of Clock dividers output signal and is changed, form the N channel parallel data, send into N electrooptic modulator respectively and carry out intensity modulated, light signal after the modulation also is advanced into the full-optical Fourier inverse transformer, the full-optical Fourier inverse transformer forms the mutually orthogonal N way carrier wave of frequency spectrum after with their conversion, and this N way carrier wave is coupled, and sends in the optical-fibre channel and transmits;

The light signal of optical-fibre channel output is sent into the full-optical Fourier converter, by conversion, light signal is divided into N way carrier wave, this N way carrier wave enters N demodulator respectively under the control of time gate, recover the N road signal of telecommunication, and be advanced into parallel-to-serial converter recovery initial data; N=2 ^m, m is the positive integer greater than 1.

4. full optical Orthogonal Frequency Division Multiplexing system as claimed in claim 3 is characterized in that:

Described time gate comprises clock signal maker and electrooptical switching, the on off state of clock signal maker control electrooptical switching, and the clock signal that the clock signal maker generates, the clock cycle is the 1/N in initial data synchronised clock cycle; The duty ratio of clock signal equals 1/N, and N is a sub-carrier number.

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