CN101626274B - Method for generating star hexadecimal optical signals, optical transmitter and system - Google Patents
Method for generating star hexadecimal optical signals, optical transmitter and system Download PDFInfo
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Abstract
本发明实施例公开了一种星型十六进制光信号的生成方法、光发射机和系统。该方法为：接收光信号，将光信号分为第一路光信号和第二路光信号；接收第一路四电平信号和第二路四电平信号；根据所述第一路四电平信号调制所述第一路光信号生成第一路正交相移键控QPSK光信号，根据所述第二路四电平信号调制所述第二路光信号生成第二路QPSK光信号；调整第一路QPSK光信号和二路QPSK光信号的相位差为π/4；将调整后的所述第一路QPSK光信号和所述第二路QPSK光信号进行合路，得到星型十六进制正交振幅调制QAM光信号。本发明实施例的方法、光发射机和系统可降低光发射机成本、简化光发射机结构、减少插入损耗和降低精确同步难度。
The embodiment of the invention discloses a method for generating a star-shaped hexadecimal optical signal, an optical transmitter and a system. The method is as follows: receiving an optical signal, dividing the optical signal into a first optical signal and a second optical signal; receiving the first four-level signal and the second four-level signal; Modulating the first optical signal with a flat signal to generate a first quadrature phase shift keying QPSK optical signal, and modulating the second optical signal according to the second four-level signal to generate a second QPSK optical signal; Adjust the phase difference between the first QPSK optical signal and the second QPSK optical signal to be π/4; combine the adjusted first QPSK optical signal and the second QPSK optical signal to obtain a star-shaped ten Hexadecimal quadrature amplitude modulation QAM optical signal. The method, optical transmitter and system of the embodiment of the present invention can reduce the cost of the optical transmitter, simplify the structure of the optical transmitter, reduce insertion loss and reduce the difficulty of precise synchronization.
Description
Technical field
The embodiment of the invention relates to the signal modulation technique field, particularly a kind of generation method of star hexadecimal optical signals and relevant device and system.
Background technology
At present; Along with extensively popularizing of Ethernet and developing rapidly of multimedia service; Based on wavelength division multiplexing (WDM; Wavelength Division Multiplexing) message capacity that optical communication system can be supported can not satisfy user's needs gradually, so the capacity that improves existing wdm optical communication system is for adapting to constantly the popularizing of network, professional fast-developing and satisfy the growing needs of user and have tangible practical significance.A kind of technical scheme of the WDM of raising optical fiber telecommunications system capacity is: the scope of the wavelength available of expansion wdm optical communication system, for example the wavelength available scope with present system expands to L-band from C-band.Because the equipment of current wdm optical communication system and device all are based on C-band, adopt this scheme to have to spend equipment and the device that great amount of cost removes to design corresponding L-band.The another kind of technical scheme that improves the wdm optical communication system capacity is: based on existing wdm system, improve the transmitted data rates of each wavelength, for example existing 10-Gb/s is brought up to 40-Gb/s, 100-Gb/s or 160-Gb/s etc.Obviously, a kind of technical scheme in back provides cost savings, and system changes little.But; Can bring a problem when adopting a kind of technical scheme in back to improve the transmission rate of each wavelength, promptly be when adopting traditional binary modulated sign indicating number type, along with the raising of channel speed; Not only the shared frequency spectrum of system can strengthen; Chromatic dispersion (CD, Chromatic Dispersion) and polarization mode dispersion transmission impairments such as (PMD, Polarization Mode Dispersion) can produce serious influence to system.Yet, adopt the multi-system modulation format not only can reduce the shared frequency spectrum of system, improve channel speed, all right enhanced system is to the resistivity of transmission impairments such as CD, PMD.
Hexadecimal quadrature amplitude modulation(PAM) (QAM; Quadrature Amplitude Modulation) light signal; Be the information that each character rate in the 16-QAM light signal carries 4 bits; Modulation signal is compared has the higher availability of frequency spectrum with QPSK (QPSK, Quadrature Phase-shift Keying).Wherein, the 16-QAM light signal can be divided into star-like 16-QAM light signal and rectangle 16-QAM light signal, is shown and can be known by research, and star-like 16-QAM light signal is higher than rectangle 16-QAM light signal to the tolerance that the light source live width has.
In addition, along with the rise of coherent optical communication technology, the coherent demodulation receiver is simple in structure owing to having, system sensitivity is high and can carry out advantages such as equilibrium and compensation to the light signal that receives, and receives people's attention all the more.So, based on the coherent light reception technique, design the optical sender of star-like 16-QAM light signal, have tangible practical significance for the capacity that improves optical communication system.
The optical transmitter structure figure of Fig. 1 star-like 16-QAM light signal of the prior art; The course of work of this optical sender is: first data-signal to be sent drives phase-modulator 1; The π phase shift takes place in the light signal of light modulated generation unit output; Second data-signal drives phase-modulator 2, and the phase shift of the light signal generation pi/2 of phase modulation modulator 1 output generates the QPSK light signal; Generate four level signals by the 3rd data-signal and the 4th data-signal through electric mixer, drive Mach-Zehnder modulator and carry out intensity modulated, the extinction ratio of control intensity-modulated signal can produce required star-like 16-QAM light signal.
As can beappreciated from fig. 1, there is following shortcoming in star-like 16-QAM optical sender of the prior art: needs use three modulators, and cost is high, system complex; Need the precise synchronization between three modulator driving signals of adjustment, adjustment work is complicated; The insertion loss of three modulator accumulative totals is big; The signal amplitude that produces is many, differentiates complicacy, and the constellation point distance is little, is subject to the phase noise influence.
Summary of the invention
The embodiment of the invention provides a kind of generation method and relevant device and system of star hexadecimal optical signals, reduces the cost of existing optical sender, simplifies the structure of existing optical sender, reduces and inserts loss, and make precise synchronization be easy to realize.
According to above-mentioned purpose, the technical scheme of the embodiment of the invention is achieved in that
The embodiment of the invention provides a kind of generation method of star hexadecimal optical signals, and said method comprises:
Receiving optical signals is divided into the first via light signal and the second road light signal with said light signal;
Receive the first via four level signals and the second tunnel four level signal;
Modulate said first via light signal according to the said first via four level signals and generate first via QPSK QPSK light signal, modulate said the second road light signal according to said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of adjusting said first via QPSK light signal and said the second road QPSK light signal is π/4;
Adjusted said first via QPSK light signal and said the second road QPSK light signal are closed the road, obtain star hexadecimal quadrature amplitude modulation QAM light signal.
The embodiment of the invention provides a kind of two modulating unit that drives, and comprising:
The light signal splitter is used for the light signal of input is divided into first via light signal and the second road light signal and output;
First phase-modulator is used to receive the first via light signal of said light signal splitter input, and receives the first via four level signals, modulates said first via light signal with the said first via four level signals and generates first via QPSK light signal; Export after adjusting the phase place of said first via QPSK light signal;
Second phase-modulator is used to receive the second road light signal of said light signal splitter input, and receives the second tunnel four level signal, modulates said the second road light signal with said the second tunnel four level signal and generates the second road QPSK light signal; Export after adjusting the phase place of said the second road QPSK light signal; The phase difference value of the said first via QPSK light signal after said the second road QPSK light signal after the adjustment phase place and the adjustment phase place is π/4; Said second phase-modulator is parallel to each other with said first phase-modulator and performance is identical;
The light signal mixer is used for the said first via QPSK light signal of said first phase-modulator output and said the second road QPSK light signal of said second phase-modulator output are closed the road, obtains the 16-QAM light signal.
The embodiment of the invention also provides a kind of optical sender, comprising:
The photogenerated unit is used to produce light signal and output;
Two driving modulating units are used to receive from the light signal of said photogenerated unit input, and the light signal of said reception is divided into the first via light signal and the second road light signal;
Receive the first via four level signals and the second tunnel four level signal of input; Modulate said first via light signal with the said first via four level signals and generate first via QPSK light signal, modulate said the second road light signal with said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of said first via QPSK light signal and said the second road QPSK light signal is adjusted into π/4;
Said first via QPSK light signal and said the second road QPSK light signal behind the adjustment phase difference are closed the road, obtain the 16-QAM light signal.
The embodiment of the invention also provides a kind of optical communication system, comprises optical sender, but said optical sender link to each other with receiver with communication mode,
Said optical sender is used for receiving optical signals, and said light signal is divided into the first via light signal and the second road light signal;
Receive the first via four level signals and the second tunnel four level signal; The said first via four level signals are generated by first data-signal and second data-signal; Said the second tunnel four level signal is generated by the 3rd data-signal and the 4th data-signal, and the speed of said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal is identical with amplitude;
Modulate said first via light signal according to the said first via four level signals and generate first via QPSK QPSK light signal, modulate said the second road light signal according to said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of adjusting said first via QPSK light signal and said the second road QPSK light signal is π/4;
Adjusted said first via QPSK light signal and said the second road QPSK light signal are closed the road; Obtain star-like 16-QAM light signal and output to said receiver, demodulation obtains said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal to said star-like 16-QAM light signal by said receiver.
Compare with the prior art that adopts a plurality of modulators to generate star-like 16-QAM light signal, the embodiment of the invention only adopts two driving modulating units and two-way four level signals can generate star-like 16-QAM light signal.Adopt two drive modulating units simple in structure, be easy to integrated and cost low; Four level signals that adopt are that speed is identical, amplitude quartering signal, generate easily.Method, optical sender and the system of the star-like 16-QAM light signal of generation that provides through the embodiment of the invention; Can reduce the cost of existing optical sender; Simplify the structure of existing optical sender simultaneously; Reduce the insertion loss that causes because of the existence of a plurality of modulators in the existing optical communication system, reduce in the existing optical communication system and adjust the difficulty that a plurality of adjuster brings because of the needs of the precise synchronization between a plurality of drive signals.
Description of drawings
Fig. 1 is the optical transmitter structure sketch map of star-like 16-QAM light signal of the prior art;
Two structural representations that drive modulating unit that Fig. 2 provides for the embodiment of the invention;
The structural representation of the four level electrical signal generation units that Fig. 3 provides for the embodiment of the invention;
The method flow diagram of the star-like 16-QAM light signal of generation that Fig. 4 provides for the embodiment of the invention;
The eye pattern of four level electrical signal that Fig. 5 provides for the embodiment of the invention;
The optical transmitter structure sketch map of the star-like 16-QAM light signal that Fig. 6 provides for the embodiment of the invention;
The planisphere of the star-like 16-QAM light signal that Fig. 7 provides for the embodiment of the invention;
The optical transmitter structure sketch map of the star-like 16-QAM of the making zero light signal that Fig. 8 provides for the embodiment of the invention;
The eye pattern of the star-like 16-QAM of the making zero light signal that Fig. 9 provides for the embodiment of the invention;
The coherent optical heterodyne communicatio structural representation of the star-like 16-QAM light signal that Figure 10 provides for the embodiment of the invention.
Embodiment
The embodiment of the invention provides a kind of generation method, optical sender and system of star-like 16-QAM light signal.Generation method, optical sender and the system of the star-like 16-QAM light signal that the embodiment of the invention provides; Not only can reduce the cost of optical sender in the existing optical communication system and the complexity of structure; Can also reduce the insertion loss of a plurality of modulators in the optical communication system, and the optical sender that the embodiment of the invention provides can also make the precise synchronization between a plurality of drive signals in the existing optical communication system be easy to realize.
For the ease of understanding, earlier the two driving modulating units and the four level signal generation units of the embodiment of the invention are introduced respectively below in conjunction with accompanying drawing to the embodiment of the invention.
See also Fig. 2, two structural representations that drive modulating unit that Fig. 2 provides for the embodiment of the invention.As shown in Figure 2, two modulating units that drive that the embodiment of the invention provides can comprise two be parallel to each other and phase-modulators that performance is identical, are respectively first phase-modulator 202 and second phase-modulator 203; Said two modulating unit that drives also comprises a light signal splitter 201 and light signal mixer 204.Wherein:
First phase-modulator 202 is used to receive the first via light signal of said light signal splitter 201 inputs, and receives the first via four level signals, modulates said first via light signal with the said first via four level signals and generates first via QPSK light signal; Export after adjusting the phase place of said first via QPSK light signal;
Second phase-modulator 203 is used to receive the second road light signal of said light signal splitter 201 inputs, and receives the second tunnel four level signal, modulates said the second road light signal with said the second tunnel four level signal and generates the second road QPSK light signal; Export after adjusting the phase place of said the second road QPSK light signal;
Wherein, the phase difference value of said the second road QPSK light signal after the adjustment phase place and the said first via QPSK light signal after the adjustment phase place is π/4; Said second phase-modulator 203 is parallel with said first phase-modulator 202 and performance is identical;
Wherein, said first phase-modulator 202 comprises:
The one QPSK light signal generation unit 205; Be used to receive the said first via light signal of said light signal splitter 201 inputs; And receive the said first via four level signals, modulate with the said first via four level signals and export after said first via light signal generates said first via QPSK light signal;
The first biasing control unit 206 is used to receive first bias voltage, receives the said first via QPSK light signal that a said QPSK light signal generation unit 205 generates, and exports adjust the phase place of said first via QPSK light signal with said first bias voltage after;
Said second phase-modulator 203 comprises:
The 2nd QPSK light signal generation unit 207; Be used to receive said the second road light signal of said light signal splitter 201 inputs; And receive said the second tunnel four level signal, modulate with said the second tunnel four level signal and export after said the second road light signal generates said the second road QPSK light signal;
The second biasing control unit 208 is used to receive second bias voltage, receives said the second road QPSK light signal that said the 2nd QPSK light signal generation unit 207 generates, and exports adjust the phase place of said the second road QPSK light signal with said second bias voltage after;
The difference of said second bias voltage and said first bias voltage is V
π/ 4, said V
πIt is the half-wave voltage of said first phase-modulator 202 and said second phase-modulator 203.
Said two modulating unit that drives can be the two Mach-Zehnder modulators that drive that comprise first parallel, the identical phase-modulator and second phase-modulator.
Above-mentioned compositions to the two driving modulating units in the embodiment of the invention describe in detail, and the two driving modulating units and two-way four level signals that provide in conjunction with the embodiment of the invention shown in Figure 2 can generate star-like 16-QAM light signal.Introduce four level signal generation units in the embodiment of the invention below in conjunction with accompanying drawing.
See also Fig. 3, the sketch map of the four level signal generation units that Fig. 3 provides for the embodiment of the invention.Said four level signal generation units can comprise:
The first amplitude adjusted subelement 301, the amplitude that is used to adjust said first data-signal are output behind 1/2 times or 2 times of former amplitude;
The first synthon unit 302; Be used to receive said first data-signal after the adjusting range of said second data-signal and the said first amplitude adjusted unit, 301 outputs, with exporting after said second data-signal that receives and the synthetic first via four level signals of said first data-signal after the said adjusting range;
The second amplitude adjusted subelement 303, the amplitude that is used to adjust said the 3rd data-signal are output behind 1/2 times or 2 times of former amplitude;
The second synthon unit 304; Be used to receive said the 3rd data-signal after the adjusting range of said the 4th data-signal and the said second amplitude adjusted unit, 403 outputs, with exporting after said the 4th data-signal that receives and synthetic the second tunnel four level signal of said the 3rd data-signal after the said adjusting range.
Can find out from the four level signal generation units that the embodiment of the invention shown in Figure 3 provides; Said first data-signal that the embodiment of the invention is identical with amplitude with speed to be sent, said second data-signal, said the 3rd data-signal and said the 4th data-signal have been divided into two groups, are respectively that said first data-signal and said second data-signal are as first group; Said the 3rd data-signal and said the 4th data-signal are as second group.Second data-signal in first group is carried out the amplitude adjustment through the 4th data-signal in the first amplitude adjusted subelement 301 and second group through the second amplitude adjusted subelement 303, and first data-signal and second data-signal close the road through the first amplitude adjusted subelement 302 afterwards; The 3rd data-signal and the 4th data-signal close the road through the second electric mixer 304, thereby obtain two-way four level signals.
More than two composition and the four level signal generation units that drive modulating units in the inventive embodiments are described in detail.Two drive the method that modulating units and four level signal generation units are introduced the star-like 16-QAM light signal of generation that inventive embodiments provides below in conjunction with what the embodiment of the invention provided.See also Fig. 4, consult Fig. 2 and Fig. 3 in the lump.The method flow diagram of the star-like 16-QAM light signal of generation that Fig. 4 provides for the embodiment of the invention, this method can may further comprise the steps:
Step 401: receiving optical signals is divided into the first via light signal and the second road light signal with said light signal.
Said light signal can be the light signal of laser input.
Step 402: receive the first via four level signals and the second tunnel four level signal.
The said first via four level signals can be generated by first data-signal and second data-signal; Said the second tunnel four level signal can be generated by the 3rd data-signal and the 4th data-signal, and the speed of said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal is identical with amplitude.
Wherein, said by first data-signal and said second data-signal generate the said first via four level signals specifically can for:
The amplitude of adjusting said first data-signal is 1/2 times or 2 times of original amplitude;
First data-signal after the said adjusting range and said second data-signal are closed the road, obtain the said first via four level signals.
Wherein, the said process that generates said the second tunnel four level signal by the 3rd data-signal and said the 4th data-signal is:
The amplitude of adjusting said the 3rd data-signal is 1/2 times or 2 times of original amplitude;
The 3rd data-signal after the said adjusting range and said the 4th data-signal are closed the road, obtain said the second tunnel four level signal.
In embodiments of the present invention, having the data-signal to be sent that four tunnel speed are identical, amplitude is identical, is respectively first data-signal, second data-signal, the 3rd data-signal and the 4th data-signal.Wherein, the amplitude of four road data-signals to be sent of supposing that said speed is identical, amplitude is identical is that low level is 0, and high point is flat to be 1.The step of said generation four level signals can for:
(1) speed is identical, four circuit-switched data signals to be sent that amplitude is identical, first data-signal, second data-signal, the 3rd data-signal and the 4th data-signal are divided into two groups, are respectively that first data-signal and second data-signal are divided into first group; The 3rd data-signal and the 4th data-signal are divided into second group.
(2) amplitude of road data-signal to be sent in first group of data-signal of adjustment is 1/2 times or 2 times of original amplitude.
For example keeping the amplitude of first data-signal to be sent constant, promptly is that low level is 0, and high level is 1; The amplitude of adjusting second data-signal to be sent is 1/2 of an original amplitude.Through the first amplitude adjusted subelement 301, is 0 with original low level with second data-signal to be sent, high level be 1 amplitude to be adjusted into low level be 0, high level is 1/2.
First data-signal that (3) will pass through in second data-signal and first group of amplitude adjustment closes the road through the first synthon unit 302, obtains the first via four level signals.
Because comprise the two paths of data signal in first group, the amplitude of first data-signal is: low level is 0, high level is 1; The amplitude of second data-signal is: low level is 0, and high level is 1/2.So the two paths of data signal in first group after the first synthon unit 302 closes the road, is obtained the first via four level signals, and said four level signals are amplitude quartering signal, its range value is respectively: 0,1/2,1,3/2.
(4) amplitude of road data-signal to be sent in second group of data-signal of adjustment is 1/2 times or 2 times of original amplitude.
For example keeping the amplitude of the 3rd data-signal to be sent constant, promptly is that low level is 0, and high level is 1; The amplitude of adjusting the 4th data-signal to be sent is 1/2 of an original amplitude.Through the second amplitude adjusted subelement 303, is 0 with original low level with the 3rd data-signal to be sent, high level be 1 amplitude to be adjusted into low level be 0, high level is 1/2.
The 3rd data-signal that (3) will pass through in the 4th data-signal and second group of amplitude adjustment closes the road through the second synthon unit 304, obtains the second tunnel four level signal.
Because comprise the two paths of data signal in second group, the amplitude of the 3rd data-signal is: low level is 0, high level is 1; The amplitude of the 4th data-signal is: low level is 0, and high level is 1/2.So the two paths of data signal in second group after the second synthon unit 304 closes the road, is obtained the second tunnel four level signal, and said four level signals are amplitude quartering signal, its range value is respectively: 0,1/2,1,3/2.
Please consult Fig. 5 in the lump, the eye pattern of four level signals that the process emulation that Fig. 5 provides for the embodiment of the invention obtains.Wherein, the signal base speed of using is 10-Gb/s; Abscissa is represented the time of four level signal emulation, and ordinate is represented the amplitude of four level signals.As can beappreciated from fig. 5, the said four level signals signal that is the amplitude quartering.
Step 403: modulate said first via light signal according to the said first via four level signals and generate first via QPSK QPSK light signal, modulate said the second road light signal according to said the second tunnel four level signal and generate the second road QPSK light signal.
The first via four level signals are loaded on pair QPSK light signal generation unit 205 of first phase-modulator 202 that drives modulating units, as the two modulating units that drive of first via drive;
The one QPSK light signal generation unit 205 utilizes the said first via four level signals to modulate and exports after said first via light signal generates said first via QPSK light signal;
The first biasing control unit 206 receives first bias voltage, and receives the said first via QPSK light signal that a said QPSK light signal generation unit 205 generates, and exports adjust the phase place of said first via QPSK light signal with said first bias voltage after;
The second tunnel four level signal is loaded on pair the 2nd QPSK light signal generation unit 207 of second phase-modulator 203 that drives modulating units, as the two modulating units that drive of the second tunnel drive;
The 2nd QPSK light signal generation unit 207 utilizes said the second tunnel four level signal to modulate and exports after said the second road light signal generates said the second road QPSK light signal.
Step 404: the phase difference of adjusting said first via QPSK light signal and said the second road QPSK light signal is π/4.
The difference that the bias voltage of loading on the second biasing control unit 208 of first biasing control unit 206 and second phase-modulator 203 of first phase-modulator 202 is set is V
π/ 4; Then the second road QPSK light signal of the first via QPSK light signal of first phase-modulator, 202 outputs and 203 outputs of second phase-modulator has the phase shift of π/4 on phase place; Said V
πIt is the half-wave voltage of first phase-modulator 202 and second phase-modulator 203.
Step 405: adjusted said first via QPSK light signal and said the second road QPSK light signal are closed the road, obtain star-like 16-QAM light signal.
With phase difference value is that the said first via QPSK light signal and said the second road QPSK light signal of π/4 advanced light signal mixer 204, obtains the 16-QAM light signal.
Need to prove; In embodiments of the present invention; The amplitude of just supposing first data-signal and the 3rd data-signal is constant; The amplitude of second data-signal and the 4th data-signal is adjusted into 1/2 times of a kind of like this mode of original amplitude, can supposes that also the amplitude of second data-signal and the 4th data-signal is constant, the amplitude of first data-signal and the 3rd data-signal is adjusted into 1/2 times or 2 times of original amplitude.The embodiment of the invention does not limit at this.
Need to prove, in the embodiment of the invention, close two-way four level signals that obtain behind the road and under the situation of needs, can also amplify.But preceding summary guarantees the input signal of amplifier within the range of linearity of amplifier, thereby guarantees that the output signal of amplifier is still four level signals of amplitude five equilibrium.
What more than combine to adopt in the embodiment of the invention twoly drives the method that modulating units and four level signal generation units have been introduced the star-like 16-QAM light signal of generation that the embodiment of the invention provides in detail.The method of utilizing the embodiment of the invention to provide not only can reduce the cost of optical sender in the existing optical communication system, the structure of simplification optical sender; Can also reduce the insertion loss of modulator in the optical communication system, and utilize this method can also make the precise synchronization between the drive signal in the optical communication system be easy to realize.
Combine two structural representation and four level signal generation units shown in Figure 3 that drive modulating unit shown in Figure 2 to introduce the optical sender that the embodiment of the invention provides below again.See also Fig. 6, the optical transmitter structure sketch map of the star-like 16-QAM light signal that Fig. 6 provides for the embodiment of the invention.This optical sender can comprise:
Four level signal generation units 602 are used to receive first data-signal and second data-signal, modulate said first data-signal and said second data-signal and produce the said first via four level signals and output to said two modulating unit 603 that drives; Receive the 3rd data-signal and the 4th data-signal, modulate said the 3rd data-signal and said the 4th data-signal and produce said the second tunnel level signal and output to said two modulating unit 603 that drives; The speed of said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal is identical with amplitude.
The speed of said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal is identical with amplitude;
Two driving modulating units 603 are used to receive from said photogenerated unit the light signal of 601 inputs, and the light signal of said reception is divided into the first via light signal and the second road light signal;
Reception is from the said first via four level signals and said the second tunnel four level signal of 602 inputs of said four level signal generation units; Modulate said first via light signal with the said first via four level signals and generate first via QPSK light signal, modulate said the second road light signal with said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of said first via QPSK light signal and said the second road QPSK light signal is adjusted into π/4;
Said first via QPSK light signal and said the second road QPSK light signal behind the adjustment phase difference are closed the road, obtain the 16-QAM light signal.
Said two modulating unit 603 that drives specifically can be the two Mach-Zehnder modulators that drive that comprise two parallel, identical phase-modulators.
Please consult Fig. 7 in the lump, Fig. 7 for the embodiment of the invention provide by the two-way phase difference value be the QPSK light signal of π/4 close rood to the planisphere of star-like 16-QAM light signal.Wherein abscissa is represented the real component of constellation point vector, and ordinate is represented the imaginary part component of constellation point.As can beappreciated from fig. 7, the planisphere of the star-like 16-QAM light signal of generation comprises 16 constellation point, the phase place of 2 amplitudes and 8 five equilibriums.So when receiving terminal is adjudicated, only need an amplitude decision threshold, just can 8 constellation point of interior circle and 8 constellation point of cylindrical be separated; Again through existing Digital Signal Processing, can be easy to rule out the phase place of the light signal of reception, thereby obtain four original circuit-switched data signals.In addition, the distance between the constellation point of the star-like 16-QAM light signal of generation is bigger, is not subject to the influence of phase noise.
Need to prove; In the embodiment of the invention; Closing two-way four level signals that obtain behind the road can also amplify under the situation of needs; But preceding summary guarantees the input signal of amplifier within the range of linearity of amplifier, thereby guarantees that the output signal of amplifier is still four level signals of amplitude five equilibrium.
The optical sender of the above-mentioned star-like 16-QAM light signal that the embodiment of the invention is provided has carried out detailed introduction.For existing optical sender; The optical sender of the star-like 16-QAM light signal that the embodiment of the invention provides can reduce the cost of existing optical sender; Simplify the structure of existing optical sender; Reduce in the existing optical communication system because the insertion loss that the existence of a plurality of modulators causes, reduce in the existing optical communication system because of the needs of the precise synchronization of a plurality of drive signals and adjust the difficulty that a plurality of modulator brings.
The above-mentioned combination embodiment of the invention provides two drives method and the optical sender that modulating units 603 and four level signal generation units 602 have at length been introduced the star-like 16-QAM light signal of generation that the embodiment of the invention provides respectively.Further combine the optical sender of the star-like 16-QAM light signal that the embodiment of the invention provides below again, introduce the another kind of optical sender that the embodiment of the invention provides in detail.
See also Fig. 8, and star-like the making zero based on the optical sender of star-like 16-QAM light signal that Fig. 8 provides for the embodiment of the invention (RZ, Return-to-Zero)-structural representation of 16-QAM optical sender.Said star-like RZ-16-QAM optical sender can comprise:
Said laser 801 is used to produce light signal and exports to said Mach-Zehnder modulator 802;
Mach-Zehnder modulator 802; Be used for receive clock drive signal and bias voltage; Light signal with said clock drive signal and the modulation of said bias voltage are imported from said laser 801 generates the RZ light pulse signal that makes zero, and exports to said two modulating unit 803 that drives;
Wherein, Light signal generation RZ light pulse signal according to said clock drive signal and 801 inputs of said bias voltage modulated laser specifically can be: according to the duty ratio of RZ light signal needs; The bias voltage of Mach-Zehnder modulator 802 and the frequency of clock signal are set, generate corresponding RZ light pulse signal.The duty ratio of RZ light signal can be 50% or 33%; When the bias voltage of Mach-Zehnder modulator 802 is located at the orthogonal points (half-power point) of transmission curve, and clock signal frequency is when identical with the base data rate, can produce duty ratio and be 50% RZ light pulse; When the bias voltage of Mach-Zehnder modulator 802 is located at the peak of transmission curve, and the frequency of clock signal is when being 1/2 times of base data rate, can produce duty ratio and be 33% RZ light pulse.
Two driving modulating units 803 are used to receive the RZ light pulse signal that said Mach-Zehnder modulator 802 is imported, and said RZ light pulse signal is divided into the first via RZ light pulse signal and the second road RZ light pulse signal;
Reception is from the said first via four level signals and said the second tunnel four level signal of said four level signal generation units input; Modulate said first via RZ light pulse signal with the said first via four level signals and generate first via QPSK light signal, modulate said the second road RZ light pulse signal with said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of said first via QPSK light signal and said the second road QPSK light signal is adjusted into π/4;
Said first via QPSK light signal and said the second road QPSK light signal behind the adjustment phase difference are closed the road, obtain the RZ-16-QAM light signal.
Please consult Fig. 9 in the lump, the duty ratio that Fig. 9 provides for the embodiment of the invention is the eye pattern of 50% star-like RZ-16-QAM light signal.Wherein, abscissa is represented the simulation time of star-like RZ-16-QAM light signal, and unit is ps, and ordinate is represented the power of star-like RZ-16-QAM light signal, and unit is uW.
Need to prove; Passing through described in the embodiment of the invention is provided with the bias voltage of Mach-Zehnder modulator 802 and the frequency of clock signal; Can generate corresponding RZ light pulse and belong to prior art, be that present technique field personnel are familiar with, and the present invention is implemented in this and does not do further introduction.
Need to prove that the Mach-Zehnder modulator 802 required clock drive signals that the embodiment of the invention provides can be inner clock signal that generates of star-like RZ-16-QAM optical sender or the outside clock signal that generates, the present invention is implemented in this and does not limit.
The optical sender that more than combines the star-like 16-QAM light signal that the embodiment of the invention provides is further introduced the optical sender of the star-like RZ-16-QAM light signal that the embodiment of the invention provides.For the optical sender of the star-like 16-QAM light signal that provides with respect to the embodiment of the invention, the photogenerated unit of the optical sender of the star-like RZ-16-QAM light signal that the embodiment of the invention provides specifically can be made up of laser and Mach-Zehnder modulator; For the light signal that generates; The optical sender of star-like RZ-16-QAM light signal is because can to generate duty ratio be 50% or 33% light signal, so the performance of the optical sender of star-like RZ-16-QAM light signal has more advantage than the optical sender of star-like 16-QAM light signal.
Below introduced the method for the star-like 16-QAM light signal of generation that the embodiment of the invention provides and the optical sender of star-like 16-QAM light signal in detail, and on the basis of the optical sender of star-like 16-QAM light signal the further optical sender of the star-like RZ-16-QAM light signal that provides of the embodiment of the invention in detail.In conjunction with the optical sender that the embodiment of the invention provides, introduce the photosystem of the star-like 16-QAM light signal of generation that the embodiment of the invention provides below.
Said optical communication system comprises the optical sender of star-like 16-QAM light signal, but the optical sender of said star-like 16-QAM light signal links to each other with coherent optical heterodyne communicatio with communication mode;
The optical sender of said star-like 16-QAM light signal is used to receive the light signal that the photogenerated unit generates, and said light signal is divided into the first via light signal and the second road light signal;
Receive the first via four level signals and the second tunnel four level signal; The said first via four level signals are generated by first data-signal and second data-signal; Said the second tunnel four level signal is generated by the 3rd data-signal and the 4th data-signal, and the speed of said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal is identical with amplitude;
Modulate said first via light signal according to the said first via four level signals and generate first via QPSK QPSK light signal, modulate said the second road light signal according to said the second tunnel four level signal and generate the second road QPSK light signal;
The phase difference of adjusting said first via QPSK light signal and said the second road QPSK light signal is π/4;
Adjusted said first via QPSK light signal and said the second road QPSK light signal are closed the road; Obtain star-like 16-QAM light signal and output to said coherent optical heterodyne communicatio, demodulation obtains said first data-signal, said second data-signal, said the 3rd data-signal and said the 4th data-signal to said star-like 16-QAM light signal by said coherent optical heterodyne communicatio.
Said coherent receiver such as Figure 10 are said, the structural representation of the coherent optical heterodyne communicatio of the star 16-QAM photosystem that Figure 10 provides for the embodiment of the invention.Said coherent optical heterodyne communicatio comprises:
First balanced reciver 1002 is used to receive said first via light signal and said the second road light signal that said 2x490 degree blender 1001 is exported, and generates the quadrature component I (t) and the output of said first via light signal and said the second road light signal;
Second balanced reciver 1003 is used to receive said Third Road light signal and said the four road light signal that said 2x490 degree blender 1002 is exported, and generates the quadrature component Q (t) and the output of said first via light signal and said the second road light signal;
Please consult Fig. 7 in the lump, this star 16-QAM light signal only comprises 2 amplitudes, so when judgement only needs an amplitude decision threshold, just can 8 constellation point of interior circle and 8 constellation point of cylindrical be separated.In 16 constellation point of this star 16-QAM light signal, only comprise the phase place of 8 five equilibriums,, can rule out the phase place of the light signal of reception by I (t) and Q (t) two paths of signals through Digital Signal Processing.According to amplitude and the phase place that judgement obtains, just can demodulate original first via data-signal, the second circuit-switched data signal, the 3rd data light signal and the 4th circuit-switched data signal.
Need to prove; The coherent optical heterodyne communicatio of the star-like 16-QAM light signal that the embodiment of the invention provides and the structure of existing coherent optical heterodyne communicatio are basic identical; The demodulation method that uses is also basic identical with the demodulation method of existing coherent optical heterodyne communicatio, so the embodiment of the invention is not done further to introduce in detail at this.
The above-mentioned optical communication system that the embodiment of the invention is provided has been carried out detailed introduction.The photosystem system that the embodiment of the invention provides can reduce the cost of existing optical sender; Simplify the structure of existing optical sender; Reduce in the existing optical communication system because the insertion loss that the existence of a plurality of modulators causes, reduce in the existing optical communication system because of the needs of the precise synchronization of a plurality of drive signals and adjust the difficulty that a plurality of modulator brings.
More than the generation method of star-like 16-QAM light signal that the embodiment of the invention is provided; Optical sender and system have carried out detailed introduction; Used concrete example among this paper principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that on embodiment and range of application, all can change, in sum, this description should not be construed as limitation of the present invention.
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| CN102137057B (en) | 2010-06-18 | 2013-09-25 | 华为技术有限公司 | Signal generation method and device |
| CN102647392A (en) * | 2011-11-30 | 2012-08-22 | 中兴通讯股份有限公司 | Star optical signal generation method and star optical signal generation device |
| CN102437985B (en) * | 2011-12-29 | 2013-10-16 | 中国人民解放军国防科学技术大学 | Method and device for modulating dual-quadrature phase shift keying signal |
| WO2012103824A2 (en) * | 2012-03-14 | 2012-08-09 | 华为技术有限公司 | Method, device, and transmission system for generating quadrature amplitude modulation signal |
| US9838239B2 (en) * | 2015-01-22 | 2017-12-05 | Futurewei Technologies, Inc. | Digital generation of multi-level phase shifting with a Mach-Zehnder modulator (MZM) |
| WO2016145641A1 (en) * | 2015-03-19 | 2016-09-22 | 华为技术有限公司 | Component and method for converting modulation format of optical signal |
| US10367586B2 (en) * | 2016-09-01 | 2019-07-30 | Juniper Networks, Inc. | Methods and apparatus for low-loss reconfigurable optical quadrature amplitude modulation (QAM) signal generation |
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| CN1493137A (en) * | 2001-11-14 | 2004-04-28 | 连宇通信有限公司 | Quadrature amplitude modulation method for digital mobile communication system |
| WO2004005972A3 (en) * | 2002-07-02 | 2004-07-15 | Celight Inc | Electro-optical integrated transmitter chip for arbitrary quadrature modulation of optical signals |
| CN101163126A (en) * | 2006-10-11 | 2008-04-16 | 中兴通讯股份有限公司 | Method of implementing QPSK modulation using 16QAM modulation |
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| CN1493137A (en) * | 2001-11-14 | 2004-04-28 | 连宇通信有限公司 | Quadrature amplitude modulation method for digital mobile communication system |
| WO2004005972A3 (en) * | 2002-07-02 | 2004-07-15 | Celight Inc | Electro-optical integrated transmitter chip for arbitrary quadrature modulation of optical signals |
| CN101163126A (en) * | 2006-10-11 | 2008-04-16 | 中兴通讯股份有限公司 | Method of implementing QPSK modulation using 16QAM modulation |
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