CN101046558A - Optical transmission system, process and equipment of mixed modulated code - Google Patents
Optical transmission system, process and equipment of mixed modulated code Download PDFInfo
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- CN101046558A CN101046558A CNA2007100990105A CN200710099010A CN101046558A CN 101046558 A CN101046558 A CN 101046558A CN A2007100990105 A CNA2007100990105 A CN A2007100990105A CN 200710099010 A CN200710099010 A CN 200710099010A CN 101046558 A CN101046558 A CN 101046558A
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Abstract
The present invention provides mixed modulated code type optical transmission system, process and equipment, and belongs to the field of optical communication. The system includes a differential phase shift keying signal loading module, a frequency shift keying signal loading module, a double parallel modulator and a demodulation module. The process includes loading the DPSK load signal onto clock signal to create loaded clock signal, modulating continuous laser beam with the loaded clock signal and FSK labeling signal in the double parallel modulator to create DPSK and FSK mixed modulated signal; receiving the mixed modulated signal in the receiving end, and demodulating to restore the DPSK load signal and the FSK labeling signal. The equipment includes a modulating module and a demodulating module. The technological scheme is used in inhibiting the non-linear effect and increasing the extinction ratio in light label exchanging and transmission system.
Description
Technical field
The present invention relates to optical communication field, particularly a kind of optical transmission system of mixed modulated code type, method and apparatus.
Background technology
Cursor sign exchange be used for full light expressway by with a kind of emerging technology of transmitting.Wherein the method for hybrid modulation commonly used is loaded into load and label information in the same light signal.In existing mixed modulated code type, load often adopts IM (IntensityModulation, amplitude modulation(PAM)) form, and label often adopts FSK (Frequency Shift Keying, frequency shift keying) or DPSK (Diffential Phase Shift Keying, differential phase keying (DPSK)) modulation format.
Referring to Fig. 1, for the IM/FSK modulation realizes block diagram, its modulated process is as follows: the light signal of laser instrument output is introduced into the FSK modulator, and this FSK modulator is by FSK label signal and f
mClock signal drives, and the FSK label signal that is loaded on the FSK modulator carries out frequency modulation (PFM) to light signal, and the carrier frequency of the light signal of FSK modulator output is had ± f than the carrier frequency of input optical signal
mFrequency deviation.Light signal after the FSK modulators modulate inputs to the IM modulator; Be loaded into load signal on the IM modulator to the light signal amplitude modulation(PAM) that tries again of input.Separate timing when label and load signal,, can directly pass through photodetector test load signal at receiving end because the modulation of FSK does not influence amplitude to the IM/FSK Hybrid-modulated Signal that receives; And the demodulation of label signal can allow light signal distinguish lower sideband signal by an optical filter earlier, detects with photodetector again.
The gordian technique that said method is used is the FSK modulator, referring to Fig. 2, be FSK modulator structure figure, this FSK modulator and single side-band modulator are very similar, form by two sub-Mach-Zehnder modulators, each sub-Mach-Zehnder modulator all has the electrode that can load radiofrequency signal, is respectively RFa and RFb, is f with a pair of frequency
mThe clock signal that the phase phasic difference is 90 ° drives; Also have an electrode RFc that can load radiofrequency signal in the junction of two sub-Mach-Zehnder modulators, be used to load fsk signal, making up and down, two branch roads produce ± 90 ° phase differential.Fig. 2 right side is the partial enlarged drawing of FSK modulator, and wherein, light path has four, and the branch road that is positioned at the sub-Mach-Zehnder modulator correspondence of branch road is path 1, path 3; Being positioned at down, the branch road of the sub-Mach-Zehnder modulator correspondence of branch road is path 2, path 4.In order to carry out the FSK modulation, two sub-Mach-Zehnder modulators all need to be biased in the minimum point place of Mach-Zehnder transmission curve, and are configured to the push-pull type working method.When fsk signal is ' 1 ', have only the center to be higher than carrier frequency f
mUpper side band be retained; When fsk signal is ' 0 ', have only the center to be lower than carrier frequency f
mLower sideband signal be retained.
This scheme is at a high speed long Distance Transmission, and the anti-non-linear behaviour of amplitude modulation(PAM) is relatively poor.In order correctly to detect the information of label, require the extinction ratio can not be too high, thereby limited the receptivity of load signal, reduced sensitivity.
Summary of the invention
The embodiment of the invention provides a kind of optical transmission system, method and apparatus of mixed modulated code type, can suppress nonlinear effect effectively, and make extinction ratio unrestricted.Technical scheme is as follows:
The embodiment of the invention provides a kind of optical transmission system of mixed modulated code type, and described system comprises:
Differential phase keying (DPSK) signal loading module is used for the differential phase keying (DPSK) load signal is loaded into clock signal, generates the load clock signal, and described load clock signal is exported to two parallel modulators;
The frequency shift keyed signals load-on module is used to generate the frequency shift keying label signal, and this frequency shift keying label signal is exported to two parallel modulators;
Two parallel modulators, be used to use the load clock signal of described differential phase keying (DPSK) signal loading module output and the frequency shift keying label signal of described frequency shift keyed signals load-on module output that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal;
Demodulation module is used for the Hybrid-modulated Signal of described two parallel modulator outputs is carried out demodulation, recovers described differential phase keying (DPSK) load signal and described frequency shift keying label signal.
The embodiment of the invention also provides a kind of optical transmission method of mixed modulated code type, and described method comprises:
The differential phase keying (DPSK) load signal is loaded on the clock signal, generates the load clock signal;
Use frequency shift keying label signal and described load clock signal that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal;
After receiving described Hybrid-modulated Signal, carry out demodulation, recover described differential phase keying (DPSK) load signal and described frequency shift keying label signal.
Further, the embodiment of the invention also provides a kind of modulation and demodulation equipment, and described equipment comprises:
Modulation module, be used for the differential phase keying (DPSK) load signal is loaded into clock signal, produce the load clock signal, use frequency shift keying label signal and described load clock signal that continuous light is modulated, produce Hybrid-modulated Signal, and export described Hybrid-modulated Signal;
Demodulation module is used for that the Hybrid-modulated Signal that receives is carried out light earlier and handles along separate routes, is divided into two-way, and one road signal is carried out the light belt pass filter, is electric signal with filtered conversion of signals then, obtains the frequency shift keying label signal; Another road signal is carried out label wipe processing, and the signal behind the erase label is interfered stack, will interfere the conversion of signals after superposeing then is electric signal, and carries out the difference processing and amplifying, obtains the differential phase keying (DPSK) load signal.
The above embodiment of the present invention uses DPSK load signal and FSK label signal that continuous light is modulated, the cursor that is applicable to long haul communication is signed exchange, can suppress nonlinear effect effectively, solve the limited problem of extinction ratio in the mixed modulation formats that contains the IM modulation format.
Description of drawings
Fig. 1 is that the IM/FSK modulation realizes synoptic diagram in the prior art;
Fig. 2 is FSK modulator structure figure in the prior art;
The optical transmission system structural drawing of the mixed modulated code type that Fig. 3 provides for the embodiment of the invention 1;
The two parallel modulator structure figure that Fig. 4 provides for the embodiment of the invention 1;
The modulating part structural drawing of the optical transmission system of the mixed modulated code type that Fig. 5 provides for the embodiment of the invention 1;
The last lower sideband that Fig. 6 provides for the embodiment of the invention 1 does not have the FSK modulation principle synoptic diagram that differs;
Load and label signal demodulation structural drawing that Fig. 7 provides for the embodiment of the invention 1;
The process flow diagram of the optical transmission method of the mixed modulated code type that Fig. 8 provides for the embodiment of the invention 2;
The modulation and demodulation equipment structure chart that Fig. 9 provides for the embodiment of the invention 3;
The modulation module structural drawing that Figure 10 provides for the embodiment of the invention 3;
The demodulation module structural drawing that Figure 11 provides for the embodiment of the invention 3.
Embodiment
Embodiment of the present invention is described further in detail below in conjunction with accompanying drawing.
The embodiment of the invention proposes a kind of optical transmission system, method and modulation and demodulation equipment of mixed modulated code type, by load signal being used the DPSK form, label adopts the FSK modulation format to transmit, suppress cursor effectively and sign the nonlinear effect that exchanges in the transmission system, and make extinction ratio unrestricted.
Embodiment 1
Referring to Fig. 3, present embodiment provides a kind of optical transmission system of mixed modulated code type, comprising:
Differential phase keying (DPSK) signal loading module, being used for the DPSK load signal is loaded into frequency is f
mClock signal on, generate the load clock signal, and the load clock signal exported to two parallel modulators;
The frequency shift keyed signals load-on module is used for the FSK label signal is exported to two parallel modulators;
Two parallel modulators, be used to use the load clock signal of differential phase keying (DPSK) signal loading module output and the FSK label signal of frequency shift keyed signals load-on module output that the continuous light that laser instrument sends is modulated, produce the Hybrid-modulated Signal of DPSK and FSK, and the output Hybrid-modulated Signal;
Demodulation module is used for the Hybrid-modulated Signal of two parallel modulator outputs is carried out demodulation, recovers former DPSK load signal and former FSK label signal.
The parallel modulator of this pair is the two parallel modulator based on two drivings, referring to Fig. 4, specifically comprises:
Three sub-Mach-Zehnder modulators are respectively sub-Mach-Zehnder modulator A, sub-Mach-Zehnder modulator B and sub-Mach-Zehnder modulator C; Each sub-Mach-Zehnder modulator all is two driven modulators, and two electrodes are arranged respectively;
Wherein, two electrode B 1, B2 on two electrode A 1 on the sub-Mach-Zehnder modulator A, A2 and the sub-Mach-Zehnder modulator B are used for the loaded load clock signal;
Two electrode C1, C2 on the sub-Mach-Zehnder modulator C, wherein, electrode C1 is the load driver signal not, and electrode C2 goes up and loads the FSK label signal.And junction A3, the B3 of sub-Mach-Zehnder modulator A, B links to each other with two electrode C1, C2 on sub-Mach-Zehnder-modulator C respectively.
Continuous light is from the junction D input of son two sub-Mach-Zehnder modulator A, B, in port A1, A2, B1, B2 input load clock signal, the continuous light of importing this modulator is modulated, light signal after the modulation is input to sub-Mach-Zehnder modulator C, by the FSK label signal of port C2 input light signal is modulated.After modulation, produce Hybrid-modulated Signal at the junction E of branch road up and down of sub-Mach-Zehnder modulator C, the last lower sideband of this Hybrid-modulated Signal does not have phase differential.
All be provided with a biasing circuit on each sub-Mach-Zehnder modulator, be used to provide dc offset voltage, make sub-Mach-Zehnder modulator A, B, C have V
πDc offset voltage, at this moment three sub-Mach-Zehnder modulators are biased in the minimum point place of Mach-Zehnder transmission curve.
Referring to Fig. 5, the differential phase keying (DPSK) signal loading module in the optical transmission system of the mixed modulated code type that present embodiment provided specifically comprises:
Sinusoidal signal generator, being used to produce frequency is f
mSinusoidal clock signal;
Electric shunt, the sinusoidal clock signal that is used for the generation of offset of sinusoidal signal generator carries out electricity along separate routes, and sinusoidal clock signal is divided into four tunnel clock signals, is respectively A1 shunt, A2 shunt, B1 shunt and B2 shunt;
Phase shifter, be used for four tunnel clock signal A1 that electric shunt is divided into along separate routes, A2 along separate routes, B1 along separate routes and B2 carry out phase shift along separate routes, make 90 ° of phase phasic differences between the adjacent two-way clock signal of four tunnel clock signals after the phase shift, and export to totalizer respectively;
The differential phase keying (DPSK) signal generator is used to produce the DPSK load signal, and the DPSK load signal is exported to totalizer;
Totalizer is used for the clock signal of phase shifter output and the DPSK load signal of differential phase keying (DPSK) signal generator output are synthesized, and obtains the load clock signal;
Amplifier is used for the load clock signal of totalizer is amplified, and the load clock signal after will amplifying outputs to two parallel modulators.
For example: the clock signal that is loaded into the A1 electrode of sub-Mach-Zehnder modulator A is cos (2 π f
mT), the clock signal of A2 electrode is cos (2 π f
mT+ π), the clock signal that is loaded into the B1 electrode of sub-Mach-Zehnder modulator B is sin (2 π f
mT), the clock signal of B2 electrode is sin (2 π f
mT+ π).Because being carried in the input signal of sub-Mach-Zehnder modulator A is cosine signal, thereby the lower sideband phase place is identical on the frequency spectrum of output place light signal, and the input signal that is carried in sub-Mach-Zehnder modulator B is a sinusoidal signal, thereby lower sideband is anti-phase on the frequency spectrum of output place light signal, and upward lower sideband all has 90 ° phase differential with the last lower sideband of sub-Mach-Zehnder modulator A.Be loaded into the A1 electrode of sub-Mach-Zehnder modulator A and the signal on the A2 electrode, and 180 ° of the phasic differences mutually of the signal on the B1 electrode that is loaded into sub-Mach-Zehnder modulator B and the B2 electrode, can suppressed carrier.
Wherein, sinusoidal signal generator also can be replaced with the cosine signal generator, and principle is identical, repeats no more.
The frequency shift keyed signals load-on module specifically comprises:
The frequency shift keyed signals transmitter is used to produce the FSK label signal;
Amplifier is used for the FSK label signal that the frequency shift keyed signals transmitter produces is amplified, and the FSK label signal after amplifying is exported to two parallel modulators.
Referring to Fig. 6, in order not influence the DPSK load signal, two sidebands up and down of FSK label signal must have identical initial phase, and therefore branch road need adopt asymmetric configuration about the sub-Mach-Zehnder modulator C, be that branch road does not add drive signal on it, only add zero offset; Its following path electrode drives with ambipolar FSK label signal, thereby can provide ± 90 ° phase shift.When branch road produces+90 ° of phase shifts under the group Mach-Zehnder modulator C, sub-Mach-Zehnder modulator B output optical signal spectrum will be rotated counterclockwise 90 °, have only upper side band to keep (among the figure shown in the solid line) up and down after the stack of branch road frequency spectrum; In like manner, when branch road produces-90 ° of phase shifts under the group Mach-Zehnder modulator C, sub-Mach-Zehnder modulator B output optical signal spectrum will turn clockwise 90 °, have only lower sideband to keep (among the figure shown in the dotted line) up and down after the stack of branch road frequency spectrum, and it be identical to catch up with the sideband phase place.This can't realize in the prior art, because of its up and down branch road have symmetry, respectively provide ± 45 ° phase shift, make that two sidebands have 90 ° of phase differential up and down.
What the FSK modulator in the existing IM/FSK mixed modulated code type adopted is single structure that drives, each sub-Mach-Zehnder interferometer has only a radio-frequency electrode, and two sidebands have 90 ° phase differential about the FSK label signal that produces, and therefore can not be used for producing the FSK label signal among the DPSK/FSK.And the two parallel modulator that present embodiment provides is six phase-modulators in essence, each phase-modulator can be used the radiofrequency signal drive, per two phase-modulators are configured to a sub-Mach-Zehnder modulator again, therefore both can produce lower sideband does not have the FSK modulation of phase differential, can also simultaneously the DPSK load signal be added on the phase place of FSK label signal again, thereby can realize DPSK and two kinds of modulation of FSK simultaneously with an integrated modulator.
An optical band pass filter can be directly passed through in the demodulation of label signal; The demodulation of load signal needs at first erase label signal, carries out balanced demodulator by a Mach-Zehnder time delay interferometer again.The erase process of label is utilized Mach-Zehnder modulator, produces the Double Sideband Suppressed Carrier modulation of going up lower sideband phase place unanimity with clock signal driven modulator two arms.
Referring to Fig. 7, demodulation module specifically comprises:
Optical branching device A is used for the Hybrid-modulated Signal of two parallel modulator outputs is carried out shunt, is divided into the two-way Hybrid-modulated Signal: shunt 1 and shunt 2;
The frequency shift keyed signals demodulating unit is used for shunt 1 Hybrid-modulated Signal after the optical branching device A shunt is carried out demodulation, reverts to former FSK label signal; Specifically carry out filtering, by photoelectric detector C light signal is converted to electric signal then, obtain former FSK label signal by optical band pass filter B;
The differential phase keying (DPSK) signal demodulation unit is used for shunt 2 Hybrid-modulated Signal after the optical branching device A shunt are carried out left and right sides frequency displacement, wipes the FSK label signal, carries out demodulation, reverts to former DPSK load signal.
Wherein, the differential phase keying (DPSK) signal demodulation unit specifically comprises:
Mach-Zehnder modulator is used for the frequency spectrum of shunt 2 Hybrid-modulated Signal after the optical branching device shunt is carried out left and right sides frequency displacement, and this Mach-Zehnder modulator frequency is f
mClock signal drive; Make f above carrier wave originally
mUpper side band signal be frequency shifted to carrier frequency left, be frequency shifted to carrier frequency top 2f to the right
mThe place; And f below carrier wave originally
mLower sideband signal be frequency shifted to carrier frequency to the right, be frequency shifted to carrier frequency below 2f left
mThe place;
Optical band pass filter A is used for wiping the FSK label signal to carrying out filtering through the Hybrid-modulated Signal after the Mach-Zehnder modulator frequency displacement, obtains carrying the light signal of DPSK load signal;
The Mach-Zehnder time delay interferometer is used for the light signal that obtains after the optical band pass filter filtering is interfered stack, will interfere the light signal after superposeing to export to photoelectric detector;
Photoelectric detector A, B are used for converting light signal to electric signal, and export to differential amplifier;
Differential amplifier is used for electric signal is amplified, output DPSK load signal.
Simultaneously, an optical branching device B is set behind optical band pass filter A, the light signal that will have the DPSK load signal is divided into two-way, wherein a road be used to carry out the demodulation of above-mentioned dpsk signal; When needs continue transmitting optical signal, again the light signal that has the DPSK load signal is write the FSK label signal by two parallel modulators, transmit again.Two parallel modulator in the optical transmission system of the configuration of the parallel modulator of this pair and above-mentioned mixed modulated code type is identical, and difference is in need not the DPSK load signal is loaded on the clock signal.
Embodiment 2
Referring to Fig. 8, the embodiment of the invention provides a kind of optical transmission method of mixed modulated code type, and concrete steps are as follows:
Step 101: it is f that sinusoidal signal generator produces frequency
mClock signal, produce four tunnel amplitudes through shunt and phase shifter and equate, the clock signal that the phasic difference of adjacent two paths of signals phase is 90 °, wherein the amplitude of clock signal is not done requirement.
For example: the clock signal that is loaded into the electrode A 1 of sub-Mach-Zehnder modulator A is cos (2 π f
mT), the clock signal of electrode A 2 is cos (2 π f
mT+ π), the clock signal that is loaded into the electrode B 1 of sub-Mach-Zehnder modulator B is sin (2 π f
mT), the clock signal of B2 electrode is sin (2 π f
mT+ π).Sub-Mach-Zehnder modulator A, the bias circuit that the dc bias circuit of B is formed by electric capacity and resistance provides, and size equals changing voltage V
π, promptly sub-Mach zehnder modulators A, B has V
πDc offset voltage.
Step 102: the DPSK load signal of four tunnel clock signals and the generation of differential phase keying (DPSK) signal generator is passed through the addition respectively of four totalizers, produce four tunnel load clock signals.Wherein DPSK is unipolar non-return-to-zero signal, and its amplitude equals the changing voltage V of sub-Mach-Zehnder modulator
π, make the DPSK load signal 180 ° depth of modulation be arranged to light signal, promptly the DPSK load signal is to phase shift difference 180 degree of light signal generating.
Step 103: after four tunnel load clock signals are amplified, be input to electrode A 1, the A2 of the sub-Mach-Zehnder modulator A in two parallel modulators respectively, the electrode B 1 of sub-Mach-Zehnder modulator B, B2.
Step 104: the bipolarity FSK label signal that the frequency shift keyed signals generator is produced is loaded on the electrode C2 of the sub-Mach-Zehnder modulator C in two parallel modulators, and the electrode C1 of sub-Mach-Zehnder modulator C is load signal not, promptly adds zero offset.
Above-mentioned steps 103 and step 104 can be carried out simultaneously, do not have sequencing.
Wherein, bipolarity FSK label signal amplitude equals the changing voltage V of sub-Mach-Zehnder modulator C
πHalf, make that the depth of modulation of branch road phase-modulator is ± 90 ° under the FSK label signal antithetical phrase Mach-Zehnder modulator C.The data transfer rate of FSK label signal should be less than the frequency of clock signal, otherwise can influence the demodulation of FSK label signal.
Step 105: two parallel adjuster maneuvering load clock signals and FSK label signal are modulated the continuous light that laser instrument sends, output DPSK/FSK Hybrid-modulated Signal.
After receiving end is received the DPSK/FSK Hybrid-modulated Signal, need carry out demodulation to it, concrete demodulation step is as follows:
Step 106: optical branching device receives Hybrid-modulated Signal, and Hybrid-modulated Signal is divided into two-way.
Step 107: one tunnel Hybrid-modulated Signal is used for recovering the FSK label signal, and Hybrid-modulated Signal is converted to changes in amplitude by optical band pass filter with frequency change, changes into electric signal by photoelectric detector again, thereby recovers the FSK label signal.
Step 108: another road Hybrid-modulated Signal is carried out wiping of label, and the light signal after wiping is divided into two-way by optical branching device B, is used for test load signal and write new label signal again respectively.
Above-mentioned steps 107 and step 108 can be carried out simultaneously, also can exchange sequencing.
Wiping of label adopts Mach-Zehnder modulator and an optical band pass filter to realize.It is f that Mach-Zehnder modulator is worked as with a frequency
mClock signal when driving, can produce the Double Sideband Suppressed Carrier modulation, and go up lower sideband and do not have phase differential, its effect is equivalent to the frequency spectrum frequency displacement to the left and right respectively with input optical signal.Make f above carrier wave originally
mUpper side band signal be frequency shifted to carrier frequency left, be frequency shifted to carrier frequency top 2f to the right
mThe place; And f below carrier wave originally
mLower sideband signal be frequency shifted to carrier frequency to the right, be frequency shifted to carrier frequency below 2f left
mThe place, the optical band pass filter that is original frequency of carrier by a centre frequency with the light signal of Mach-Zehnder modulator output can be wiped label signal again, recovers original DPSK load signal.Mach-Zehnder modulator herein both can adopt stagged electrode structure, also can adopt the bipolar electrode structure, for example: if directly use cos (2 π f with single electrode
mT) driving gets final product; If use bipolar electrode, two electrodes are imported cos (2 π f respectively up and down
mT) and cos (2 π f
mT+ π).
The process that light signal behind one road erase label is recovered former DPSK load signal is specially: by the Mach-Zehnder time delay interferometer light signal is interfered stack, at two output ports light signal all is input to photoelectric detector then, photoelectric detector is converted into electric signal with the light signal that receives, and electric signal is input to differential amplifier, differential amplifier carries out processing and amplifying to electric signal again, output load signal---former DPSK load signal, this mode improves 3dB than single-ended detection receiver sensitivity.
The process that light signal behind another road erase label writes new label again is similar with generation DPSK/FSK modulation, still adopt the two parallel modulator of identical configuration, difference is in need not the DPSK load signal is loaded on the clock signal, and the purpose that light signal is loaded new label is used for transmitting to far-end once more.
Embodiment 3
Referring to Fig. 9, a kind of modulation and demodulation equipment comprises:
Modulation module is used for the differential phase keying (DPSK) load signal is loaded into clock signal, produces the load clock signal, uses frequency shift keying label signal and load clock signal that continuous light is modulated, and produces Hybrid-modulated Signal, and the output Hybrid-modulated Signal;
Demodulation module is used for that the Hybrid-modulated Signal that receives is carried out light earlier and handles along separate routes, is divided into two-way, and one road signal is carried out the light belt pass filter, is electric signal with filtered conversion of signals then, obtains the FSK label signal; Another road signal is carried out label wipe processing, and the signal behind the erase label is interfered stack, will interfere the conversion of signals after superposeing then is electric signal, and carries out the difference processing and amplifying, obtains the DPSK load signal.
Referring to Figure 10, modulation module specifically comprises:
Differential phase keying (DPSK) signal loading module is used for the differential phase keying (DPSK) load signal is loaded into clock signal, generates the load clock signal, and the load clock signal is exported to two parallel modulators;
The frequency shift keyed signals load-on module is used to generate the frequency shift keying label signal, and this frequency shift keying label signal is exported to two parallel modulators;
Two parallel modulators, be used to use the load clock signal of differential phase keying (DPSK) signal loading module output and the frequency shift keying label signal of frequency shift keyed signals load-on module output that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and the output Hybrid-modulated Signal.
The two parallel modulator here can adopt Mach Ceng Deshuan modulator that walks abreast, and its structural drawing specifically comprises as shown in Figure 4:
Three sub-Mach-Zehnder modulators are respectively sub-Mach-Zehnder modulator A, sub-Mach-Zehnder modulator B and sub-Mach-Zehnder modulator C; Each sub-Mach-Zehnder modulator all is two driven modulators, and two electrodes are arranged respectively;
Wherein, two electrode B 1, B2 on two electrode A 1 on the sub-Mach-Zehnder modulator A, A2 and the sub-Mach-Zehnder modulator B are used for the loaded load clock signal;
Two electrode C1, C2 on the sub-Mach-Zehnder modulator C, wherein, electrode C1 is the load driver signal not, and electrode C2 goes up and loads the FSK label signal.And junction A3, the B3 of sub-Mach-Zehnder modulator A, B links to each other with two electrode C1, C2 on the son Mach zehnder modulators C respectively.
Continuous light is from the junction D input of son two sub-Mach-Zehnder modulator A, B, in port A1, A2, B1, B2 input load clock signal, the continuous light of importing this modulator is modulated, light signal after the modulation is input to sub-Mach-Zehnder modulator C, by the FSK label signal of port C2 input light signal is modulated.After modulation, produce Hybrid-modulated Signal at the junction E of branch road up and down of sub-Mach-Zehnder modulator C.The last lower sideband of this Hybrid-modulated Signal does not have phase differential.
All be provided with a biasing circuit on each sub-Mach-Zehnder modulator, be used to provide dc offset voltage, make sub-Mach-Zehnder modulator A, B, C have V
πDc offset voltage, at this moment three sub-Mach-Zehnder modulators are biased in the minimum point place of Mach-Zehnder transmission curve.
Referring to Figure 11, demodulation module specifically comprises:
Optical branching device, the Hybrid-modulated Signal that is used for receiving is carried out shunt, is divided into the two-way Hybrid-modulated Signal: shunt 1 and shunt 2;
The frequency shift keyed signals demodulating unit is used for shunt 1 Hybrid-modulated Signal after the optical branching device shunt is carried out demodulation, reverts to former FSK label signal; Specifically can carry out filtering, by photoelectric detector light signal is converted to electric signal then, obtain the FSK label signal by optical band pass filter;
The differential phase keying (DPSK) signal demodulation unit is used for shunt 2 Hybrid-modulated Signal after the optical branching device shunt are carried out left and right sides frequency displacement, wipes the FSK label signal, carries out demodulation then, recovers the DPSK load signal.
Above embodiment uses DPSK load signal and FSK label signal that continuous light is modulated, the cursor that is applicable to long haul communication is signed exchange, can suppress nonlinear effect effectively, solved the limited problem of extinction ratio in the mixed modulation formats that contains the IM modulation format, and the sensitivity that has improved receiver;
Simultaneously, two parallel modulators have been realized the combination of two kinds of phase modulation techniques (DPSK and FSK), are easy to integrated.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. the optical transmission system of a mixed modulated code type is characterized in that, described system comprises:
Differential phase keying (DPSK) signal loading module is used for the differential phase keying (DPSK) load signal is loaded into clock signal, generates the load clock signal, and described load clock signal is exported to two parallel modulators;
The frequency shift keyed signals load-on module is used to generate the frequency shift keying label signal, and this frequency shift keying label signal is exported to two parallel modulators;
Two parallel modulators, be used to use the load clock signal of described differential phase keying (DPSK) signal loading module output and the frequency shift keying label signal of described frequency shift keyed signals load-on module output that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal;
Demodulation module is used for the Hybrid-modulated Signal of described two parallel modulator outputs is carried out demodulation, recovers described differential phase keying (DPSK) load signal and described frequency shift keying label signal.
2. the optical transmission system of mixed modulated code type as claimed in claim 1 is characterized in that, described differential phase keying (DPSK) signal loading module specifically comprises:
Sinusoidal signal generator is used to produce sinusoidal clock signal;
Electric shunt is used for the sinusoidal clock signal that described sinusoidal signal generator produces is carried out electricity along separate routes, and described sinusoidal clock signal is divided into four tunnel clock signals;
Phase shifter is used for four tunnel clock signals that described electric shunt is divided into are carried out phase shift, makes 90 ° of phase phasic differences between the adjacent two-way clock signal of described four tunnel clock signals, and the clock signal after the phase shift is exported to totalizer;
The differential phase keying (DPSK) signal generator is used to produce the differential phase keying (DPSK) load signal, and described differential phase keying (DPSK) load signal is exported to totalizer;
Totalizer is used for the clock signal of described phase shifter output and the differential phase keying (DPSK) load signal of described differential phase keying (DPSK) signal generator output are synthesized, and produces the load clock signal;
Amplifier is used for the load clock signal that described totalizer produces is amplified, and the load clock signal after will amplifying outputs to described two parallel modulator.
3. the optical transmission system of mixed modulated code type as claimed in claim 2 is characterized in that, described two parallel modulators specifically comprise:
Three sub-Mach-Zehnder modulators are respectively the first sub-Mach-Zehnder modulator, the second sub-Mach-Zehnder modulator and the 3rd sub-Mach-Zehnder modulator; Each sub-Mach-Zehnder modulator all is two driven modulators, and two electrodes are arranged respectively;
Wherein, two electrodes on the described first sub-Mach-Zehnder modulator and two electrodes on the second sub-Mach-Zehnder modulator are used to load the load clock signal of described amplifier output; Two electrodes on the described the 3rd sub-Mach-Zehnder modulator are respectively applied for and load described frequency shift keying label signal;
A biasing circuit also is set respectively on each sub-Mach-Zehnder modulator, is used to provide dc offset voltage.
4. the optical transmission system of mixed modulated code type as claimed in claim 1 is characterized in that, described demodulation module specifically comprises:
Optical branching device is used for the Hybrid-modulated Signal of described two parallel modulator outputs is carried out shunt, is divided into the two-way Hybrid-modulated Signal;
The frequency shift keyed signals demodulating unit is used for road Hybrid-modulated Signal after the described optical branching device shunt is carried out demodulation, recovers described frequency shift keying label signal;
The differential phase keying (DPSK) signal demodulation unit is used for another road Hybrid-modulated Signal after the described optical branching device shunt is carried out left and right sides frequency displacement, wipes described frequency shift keying label signal, carries out demodulation, recovers described differential phase keying (DPSK) load signal.
5. the optical transmission system of mixed modulated code type as claimed in claim 4 is characterized in that, described differential phase keying (DPSK) signal demodulation unit specifically comprises:
Mach-Zehnder modulator is used for the frequency spectrum of another road Hybrid-modulated Signal after the described optical branching device shunt is carried out left and right sides frequency displacement, and described Mach-Zehnder modulator drives with clock signal;
Optical band pass filter is used for wiping described frequency shift keying label signal to carrying out filtering through the Hybrid-modulated Signal after the described Mach-Zehnder modulator frequency displacement, obtains carrying the light signal of differential phase keying (DPSK) load signal;
The Mach-Zehnder time delay interferometer is used for the light signal that obtains after the described optical band pass filter filtering is interfered stack, will interfere the light signal after superposeing to export to photoelectric detector;
Photoelectric detector is used for converting the light signal after the described interference stack to electric signal, and exports to differential amplifier;
Differential amplifier is used for described electric signal is amplified, and exports described differential phase keying (DPSK) load signal.
6. the optical transmission system of mixed modulated code type as claimed in claim 5 is characterized in that, described differential phase keying (DPSK) signal demodulation unit also comprises:
Optical branching device is used for the light signal that carries the differential phase keying (DPSK) load signal of described optical band pass filter output is divided into two-way, and one road signal is exported to described Mach-Zehnder time delay interferometer, and another road signal is exported to two parallel modulators;
Two parallel modulators, be used to use the frequency shift keying label signal that the described light signal that carries the differential phase keying (DPSK) load signal that receives is modulated again, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal.
7. the optical transmission method of a mixed modulated code type is characterized in that, described method comprises:
The differential phase keying (DPSK) load signal is loaded on the clock signal, generates the load clock signal;
Use frequency shift keying label signal and described load clock signal that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal;
After receiving described Hybrid-modulated Signal, carry out demodulation, recover described differential phase keying (DPSK) load signal and described frequency shift keying label signal.
8. the optical transmission method of mixed modulated code type as claimed in claim 7 is characterized in that, described the differential phase keying (DPSK) load signal is loaded on the clock signal, and the step that generates the load clock signal specifically comprises:
The offset of sinusoidal clock signal is carried out electricity along separate routes, and described sinusoidal clock signal is divided into four tunnel clock signals;
Described four tunnel clock signals are carried out phase shift, make 90 ° of phase phasic differences between adjacent two clock signals of described four tunnel clock signals;
Differential phase keying (DPSK) load signal and described clock signal are synthesized and amplify, generate the load clock signal.
9. the optical transmission method of mixed modulated code type as claimed in claim 7, it is characterized in that, described receive described Hybrid-modulated Signal after, carry out demodulation, the step that recovers described differential phase keying (DPSK) load signal and described frequency shift keying label signal specifically comprises:
After receiving described Hybrid-modulated Signal, carry out light earlier and handle along separate routes, described Hybrid-modulated Signal is divided into two-way;
One road signal is carried out the light belt pass filter, is electric signal with filtered conversion of signals then, obtains described frequency shift keying label signal;
Another road signal is carried out label wipe processing, and the signal behind the erase label is interfered stack, will interfere the conversion of signals after superposeing then is electric signal, and carries out the difference processing and amplifying, obtains described differential phase keying (DPSK) load signal.
10. the optical transmission method of mixed modulated code type as claimed in claim 7, it is characterized in that, described receive described Hybrid-modulated Signal after, carry out demodulation, the step that recovers described differential phase keying (DPSK) load signal and described frequency shift keying label signal specifically comprises:
After receiving described Hybrid-modulated Signal, carry out light earlier and handle along separate routes, described Hybrid-modulated Signal is divided into two-way;
One road signal is carried out the light belt pass filter, is electric signal with filtered conversion of signals then, obtains described frequency shift keying label signal;
Another road signal is carried out label wipe processing, signal behind the erase label is divided into two-way, use the frequency shift keying label signal to modulate again road signal wherein, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal; Another road signal is wherein interfered stack, be electric signal with interfering the conversion of signals after superposeing, and carry out the difference processing and amplifying, obtain described differential phase keying (DPSK) load signal.
11. a modulation and demodulation equipment is characterized in that, described equipment comprises:
Modulation module, be used for the differential phase keying (DPSK) load signal is loaded into clock signal, produce the load clock signal, use frequency shift keying label signal and described load clock signal that continuous light is modulated, produce Hybrid-modulated Signal, and export described Hybrid-modulated Signal;
Demodulation module is used for that the Hybrid-modulated Signal that receives is carried out light earlier and handles along separate routes, is divided into two-way, and one road signal is carried out the light belt pass filter, is electric signal with filtered conversion of signals then, obtains the frequency shift keying label signal; Another road signal is carried out label wipe processing, and the signal behind the erase label is interfered stack, will interfere the conversion of signals after superposeing then is electric signal, and carries out the difference processing and amplifying, obtains the differential phase keying (DPSK) load signal.
12., it is characterized in that described modulation module specifically comprises as claim 11 modulation and demodulation equipment:
Differential phase keying (DPSK) signal loading module is used for the differential phase keying (DPSK) load signal is loaded into clock signal, generates the load clock signal, and described load clock signal is exported to two parallel modulators;
The frequency shift keyed signals load-on module is used to generate the frequency shift keying label signal, and this frequency shift keying label signal is exported to two parallel modulators;
Two parallel modulators, be used to use the load clock signal of described differential phase keying (DPSK) signal loading module output and the frequency shift keying label signal of described frequency shift keyed signals load-on module output that the continuous light that laser instrument sends is modulated, generation has the Hybrid-modulated Signal of differential phase keying (DPSK) and frequency shift keying sign indicating number type, and exports described Hybrid-modulated Signal.
13., it is characterized in that described demodulation module specifically comprises as claim 11 modulation and demodulation equipment:
Optical branching device, the Hybrid-modulated Signal that is used for receiving is carried out shunt, is divided into the two-way Hybrid-modulated Signal;
The frequency shift keyed signals demodulating unit is used for road Hybrid-modulated Signal after the described optical branching device shunt is carried out demodulation, recovers described frequency shift keying label signal;
The differential phase keying (DPSK) signal demodulation unit is used for another road Hybrid-modulated Signal after the described optical branching device shunt is carried out left and right sides frequency displacement, wipes described frequency shift keying label signal, carries out demodulation, recovers described differential phase keying (DPSK) load signal.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101635700B (en) * | 2008-07-25 | 2012-08-08 | 华为技术有限公司 | ASK/DPSK hybrid modulation method, device and system |
| CN105119855A (en) * | 2015-07-10 | 2015-12-02 | 电子科技大学 | Modulation and demodulation method and apparatus |
| CN109644014A (en) * | 2016-11-30 | 2019-04-16 | 华为技术有限公司 | A kind of signal processing method, device and fibre-optic transmission system (FOTS) |
-
2007
- 2007-05-08 CN CNB2007100990105A patent/CN100487526C/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101635700B (en) * | 2008-07-25 | 2012-08-08 | 华为技术有限公司 | ASK/DPSK hybrid modulation method, device and system |
| CN105119855A (en) * | 2015-07-10 | 2015-12-02 | 电子科技大学 | Modulation and demodulation method and apparatus |
| CN105119855B (en) * | 2015-07-10 | 2018-03-02 | 电子科技大学 | A kind of modulation and demodulation method and device |
| CN109644014A (en) * | 2016-11-30 | 2019-04-16 | 华为技术有限公司 | A kind of signal processing method, device and fibre-optic transmission system (FOTS) |
| US10673534B2 (en) | 2016-11-30 | 2020-06-02 | Huawei Technologies Co., Ltd. | Signal processing method, apparatus, and optical fiber transmission system |
| CN109644014B (en) * | 2016-11-30 | 2020-06-16 | 华为技术有限公司 | Signal processing method and device and optical fiber transmission system |
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| CN100487526C (en) | 2009-05-13 |
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