CN104717166B - A kind of FSK modulation system based on filtering modulator - Google Patents
A kind of FSK modulation system based on filtering modulator Download PDFInfo
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Abstract
The invention discloses a kind of FSK modulation system based on filtering modulator, it can produce continuous FSK optical signals, can be used as optical tag or optics payload, and FSK modulation system includes laser, LiNbO3Modulator, random signal generator, sinusoidal signal generator, 2 phase inverters and filtering modulator；Wherein laser produces continuous laser, into LiNbO3Modulator, under the driving of sinusoidal signal, outgoing carrier is drawn up subcarrier；Carrier wave draws up subcarrier into filtering modulator block, is modulated under the driving of data-signal, obtains frequency difference, the symmetrical flashlight of strength mis-matching, and then couple and obtain required fsk signal.The present invention utilizes a LiNbO3Modulator and filtering modulator block realize fsk signal, relative to existing FSK modulation mode, have the advantages that signal modulation is stable, and external factor influence is small, and each frequency component amplitudes difference is small, therefore signal transmission dispersive influence is small, and integrated level is high.
Description
Technical field
The invention belongs to photoelectron, optical communication field, more particularly, to a kind of FSK modulation based on filtering modulator
System.
Background technology
Primary modulation form in optic communication includes：Based on Modulation and Amplitude Modulation ASK (Amplitude Shift Keying,
Amplitude-shift keying) modulation, PSK (Phase Shift keying, the phase keying) modulation based on phase-modulation, based on frequency modulation(PFM)
FSK (Frequency Shift keying, frequency keying) modulation, and the Polarization Modulation based on polarization.Wherein FSK conducts
A kind of modulating mode being recently proposed, due to having very high transmission tolerance in transmitting procedure；Demodulation for fsk signal
Mode only needs optical filter, demodulates the advantage such as convenient, increasingly causes the concern of people.
Existing FSK modulation mode has：(1) output of laser frequency is changed by adjusting the control electric current of laser
Rate, to reach the purpose of different frequency output, but such a mode, due to the conversion for not reaching high speed of control electric current, and
The limitation of signal response speed, fsk signal speed are less than 10Gb/s, can not produce high speed fsk signal.(2) it is integrated using 3
Mach increases Dare modulator control, and the pattern for modulating lower sideband respectively produces, but this device is limited to the water of production technology
It is flat, it is difficult to produce such a device.(3) two lasers or CSRZ (Carrier Suppressed Retune to are utilized
Zero, carrier wave are drawn up NRZ) pattern, two subcarriers are produced, subcarrier is modulated into DPSK (Differential Phase
Shift Keying, differential phase keying (DPSK)) signal, signal is then sent into time delay interferometer effect is demodulated to DPSK, by two
Subcarrier corresponds respectively to MZDI (Mach-Zehnder Delay Interferometer, Mach increase Dare delay interferometer)
Output maximum and minimum value, and then produce fsk signal.But this method structure is more complicated, to pass through repeatedly modulation
And demodulating process.
The content of the invention
The defects of for prior art, it is an object of the invention to provide a kind of FSK modulation system based on filtering modulator
System, it is intended to solve in the prior art that carrier frequency amplitude is unequal, modulation rate is low, the bit error rate is high and system in fsk signal
The problem of complicated.
The invention provides a kind of FSK modulation system based on filtering modulator, including sinusoidal signal generator, laser
Device, the first phase inverter, LiNbO3Modulator, data signal generator, the second phase inverter and filtering modulator；Described first is anti-phase
The input of device is connected to the output end of the sinusoidal signal generator, and the output end of first phase inverter is connected to described
LiNbO3The upper arm control port of modulator；The LiNbO3The input of modulator is connected to the output end of the laser, institute
State LiNbO3The underarm control port of modulator is connected to the output end of the sinusoidal signal generator；Second phase inverter
Input is connected to the output end of the data signal generator, and the output end of second phase inverter is connected to the filtering and adjusted
The upper arm control terminal of device processed, the input of the filtering modulator are connected to the LiNbO3The output end of modulator, the filter
The underarm control port of wave modulator is connected to the output end of the data signal generator, the output end of the filtering modulator
Output end as FSK modulation system.
Wherein, during work, the drive signal of the sinusoidal signal generator output is divided into two-way, is loaded directly into all the way in institute
State LiNbO3The underarm control terminal of modulator, another way reload the LiNbO after back-modulation3The upper arm of modulator
Control terminal, the LiNbO3Modulator is modulated to the continuous laser signal that laser exports, and is produced carrier wave and is drawn up subcarrier
Signal, this signal includes two subcarrier components, and carrier component is drawn up；Hereafter, subcarrier signal enters filtering modulator,
This modulator has the function of filtering and modulation, and the subcarrier signal for initially entering modulator divides two-way respectively by by FBG structures
Into two paths up and down, complete carrier wave separation effect, then by external signal in the intensity modulator of upper and lower two-arm
Effect is lower to carry out intensity modulated, optical signal is referred to as the different optical signal of strength mis-matching, frequency, in filtering modulator output end coupling
After conjunction, as fsk signal, the signal of driving filtering modulator is data-signal, and data-signal is produced by data signal generator,
Filtering modulator is loaded directly into all the way to be modulated light wave, is loaded into filtering modulator to light wave through the second phase inverter all the way
It is modulated, therefore the light carrier of the two-arm up and down by two paths of data modulation is the flashlight that amplitude couples, frequency is different.
Wherein, the LiNbO3The continuous laser that modulator exports to laser is modulated, and its transfer function is：
Wherein, L is insertion loss, r LiNbO3The splitting ratio of the upper and lower two-arm of modulator, ER are LiNbO3 modulators
Upper and lower two-arm extinction coefficient,The phase of respectively upper and lower arm, V1(t)、V2(t) it is respectively
The driving voltage of upper and lower two-arm, VπRF、VπDCFor LiNbO3The half-wave voltage of modulator, VB1、VB2Respectively upper and lower two-arm it is inclined
Put voltage.
Wherein, it is described filtering modulator include the first coupler, the first Bragg grating optical fiber, the first intensity modulator,
Second Bragg grating optical fiber, the second intensity modulator and the second coupler；The input of first coupler is connected to institute
State LiNbO3The output end of modulator, one end of first Bragg grating optical fiber and the first output of first coupler
End connection, one end of second Bragg grating optical fiber is connected with the second output end of first coupler；Described first
The input of intensity modulator is connected to the other end of first Bragg grating optical fiber, the control of first intensity modulator
End processed is connected as the upper arm control terminal of the filtering modulator with the output end of second phase inverter；Second intensity is adjusted
The input of device processed is connected to the other end of second Bragg grating optical fiber, and the control terminal of second intensity modulator is made
Underarm control terminal for the filtering modulator is connected with the output end of the number generator；The first of second coupler
Input is connected to the output end of first intensity modulator, and the second input of second coupler is connected to described
The output end of two intensity modulators, the output end of second coupler is as the output end for filtering modulator.
Wherein, the center filter wavelength and LiNbO of first Bragg grating optical fiber3The subcarrier of modulator output
Wavelength matched, bandwidth is equal.
Compared with prior art, the present invention uses a laser, utilizes LiNbO3The modulating action of modulator produces two
Frequency of the individual subcarrier component as carrying signal, the difference in size of the amplitude of different frequency component is reduced, improves the steady of signal
It is qualitative, influence of the dispersion of signal transmission to fsk signal is improved, reduces the bit error rate.Meanwhile the present invention propose it is a kind of new
Modulator --- modulator is filtered, input waveguide is FBG optical fiber, can complete partial wave, the effect of filtering, preferably ensure frequency
The constant amplitude of component, reduce external factors influences on modulating frequency and amplitude, is further ensured that stability and the dispersion pair of signal
The influence of signal.In addition, the present invention also carries out the loading of signal message and the generation of fsk signal using filtering strength modulator,
Modulation system is simple, features simple structure.
Brief description of the drawings
Fig. 1 is the theory diagram of FSK modulation system provided in an embodiment of the present invention；
Fig. 2 is the structural representation of laser provided in an embodiment of the present invention and LiNbO3 modulator operational modules；
Fig. 3 is the structural representation of filtering strength modulator operational module provided in an embodiment of the present invention.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, it is right below in conjunction with drawings and Examples
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
In order to overcome the above-mentioned deficiencies of the prior art, the invention provides a kind of FSK modulation structure.Such a structure can produce
The fsk signal of raw high speed, and it is simple in construction.
In embodiments of the present invention, the continuous light for coming from laser passes through LiNbO3The modulating action of modulator produces load
Ripple is drawn up signal, and this signal includes two subcarriers, and subcarrier signal enters filtering modulator, adopted in the input interface of this device
With FBG optical fiber, it can not only play a part of filtering, can also be to ensureing that input light wave is modulated into upper and lower two-arm
When amplitude it is equal, for input light wave under FBG filter actions, upper and lower two-arm produces unifrequency subcarrier frequency signals, amplitude phase
Deng respectively enteing the intensity modulator of upper and lower two-arm, intensity modulator is under the signal function of outside drive signal respectively to two
Individual frequency component is modulated, and produces the flashlight of complementary intensity, is exactly fsk signal after coupling.
The structure of FSK modulation system provided in an embodiment of the present invention is as shown in figure 1, FSK modulation system includes：Sinusoidal signal
Generator 1, laser 2, the first phase inverter 3, LiNbO3Modulator 4, data signal generator 5, the second phase inverter 6 and filtering are adjusted
Device 7 processed；The output end and LiNbO of laser 23The input of modulator 4 is connected；The output of sinusoidal signal generator 1 is through dividing
Lu Hou, all the way the input with the first phase inverter 3 be connected, another way and LiNbO3The underarm control port connection of modulator 4；The
The output end and LiNbO of one phase inverter 33The underarm control port connection of modulator 4；The output end of data signal generator 5 point
Two paths of data signal, all the way the input with the second phase inverter 6 be connected, another way with filtering modulator 7 underarm control port
Connection；The output end of second phase inverter 6 with filter modulator 7 upper arm control port be connected, filter modulator 7 input and
LiNbO3The output end connection of modulator 4, filters output end of the output end of modulator 7 as FSK modulation system.
Wherein, LiNbO3Modulator 4 has 4 interfaces, respectively 1 input interface, 2 control interfaces, and 1 output connects
Mouthful, input interface is connected with the output of laser 2, and output interface is connected with filtering the input interface of modulator 7, upper arm control interface
It is connected with the output interface of the first phase inverter 3, underarm control interface is connected with sinusoidal signal generator 1.
Filtering modulator 7 has 4 interfaces, respectively 1 input interface, 1 output interface, 2 control interfaces, input
Interface and LiNbO3The output interface connection of modulator 4, upper arm control interface are connected with the output interface of the second phase inverter 6, under
Arm control interface is connected with the output port of data signal generator 5, and output port is the output end of total system.
In embodiments of the present invention, sinusoidal signal generator 1 produces sine wave signal, frequency-adjustable, this sine wave signal
Light wave can be modulated, frequency of light wave is produced subcarrier, the carrier frequency for FSK modulation；Laser 2 can be to connect
Continuous light laser, the arrowband light wave used in generation system, as modulation and the carrier signal of carry data signals；First phase inverter
3 be to allow the positive negative level of sinusoidal signal to invert, and conjugated signal is produced, for modulating LiNbO3Modulator 4, makes LiNbO3Adjust
Device 4 processed is operated in the state of recommending, from LiNbO3The light wave exported in modulator 4 is CSRZ light waves, only contains subcarrier component；
LiNbO3Modulator 4 is the main devices for producing CSRZ signals, and this device is completed under the modulation of external control signal to input
Light wave modulation, produce carrier wave and draw up subcarrier, for future use, because two frequency signals of fsk signal thus device completely
Produce, compared to two lasers export system of two frequencies as FSK carrier frequency, and the system being capable of strict guarantee two-way FSK
Stability and two-way laser frequency, phase, the amplitude matching of frequency signal；Data signal generator 5 is transmission signal
Signal generator, as modulated signal；Phase inverter of second phase inverter 6 as data signal generator 5, can using this phase inverter
With by the level of data-signal invert, will ' 0 ', ' 1 ' signal reversion, therefore data signal generator 5 two paths of signals pass through
The signal that second phase inverter 6 is loaded into after filtering modulator 7 is ' 0 ', ' 1 ' coupled signal；Filter the master that modulator 7 is the system
Device is wanted, this device can complete the generation of fsk signal, and this device can be done directly the effect of filtering and modulation, because upper,
The full symmetric property of lower two-arm, the amplitude difference of two-way frequency signal can be made, ensure the amplitude stabilization of fsk signal, reduce FSK
The factors such as the dispersion of signal transmission influence.
In embodiments of the present invention, the internal structure of modulator 7 is filtered as shown in figure 3, filtering modulator 7 includes the first coupling
Clutch 71, the first Bragg grating optical fiber 72, the first intensity modulator 73, the second Bragg grating optical fiber 74, the second intensity are adjusted
The coupler 76 of device 75 and second processed；First coupler 71 has two output ends of an input, and an input port is outside defeated
Inbound port, two output ports connect the input of the first Bragg grating optical fiber 72 and the second Bragg grating optical fiber 74 respectively
Mouthful；The output interface of first Bragg grating optical fiber 72 is connected with the input interface of the first intensity modulator 73；Second Prague light
The output interface of grid optical fiber 74 is connected with the input interface of the second intensity modulator 75；First intensity modulator 73 and the second intensity
The output interface of modulator 75 is connected with the input interface of the second coupler 76；The output interface of second coupler 76 is adjusted for filtering
The output interface of device 7 processed.First coupler 71 act as partial wave, by light wave 1:1 two Bragg grating optical fibers of entrance；Cloth
Glug grating fibers complete the filter effect to the subcarrier of input, the center filter wavelength and subcarrier of Bragg grating optical fiber
It is Wavelength matched, bandwidth is equal, and the light carrier of output can be made except different in centre frequency, other complete phases of optical information
Together, therefore matching, the identity property of FSK two frequency components can be ensured, that is, ensure the stabilization and transmission performance of fsk signal
It is good；First intensity modulator 73 and the second intensity modulator 75 are to complete the modulation of signal, and data-signal is loaded into light
On ripple；Second coupler 76 is the light wave for being coupled as a permanent power for completing two-way light carrier, and this light wave has ensured in amplitude
Complete is constant, and then improves the transmission performance of fsk signal, improves the ability for dispersion of drawing up.
Modulator 7 is filtered for other intensity modulators, this modulator employs Prague on input waveguide
Grating fibers, can be not only complete as the input waveguide of input intensity modulator due to the good welding performance of grating fibers
Into the effect of light-path, and the effect of filtering is completed, because a key factor of FSK modulation is ensuring that the two of fsk signal
The constancy of individual carrying Frequency and Amplitude, therefore for the device of filtered external, transmission waveguide is adopted in this filtering modulator
With Bragg grating optical fiber, it is possible to ensure the constant of the light path in light wave transmissions with stably, ensureing the device in two paths of signals
Part has ensured to ensure that influence of the external factors to signal light-wave consistent therefore fine, and up and down in two-way optical signal pair
Become second nature, and make the consistent of the amplitude of two optical carrier frequencies, therefore the amplitude of caused fsk signal is more stable, reduces
During optical signal transmission in optical fiber dispersion influence, improve the transmission quality of signal.
The continuous light for coming from laser 2 passes through LiNbO3The modulating action of modulator 4 produces carrier wave and drawn up signal, this letter
Number two subcarrier signals are included, carrier component is by very big effect of drawing up；This signal is sent into filtering modulator 7, this is strong
The input port for spending modulator uses Bragg grating optical fiber as input optical fibre, therefore optical signal is by 1:1 partial wave, Prague light
Grid optical fiber filters, and produces the information matches such as optical signal, the equal, phase of amplitude of the two signals of two independent frequency components；
Filter modulator about 7 two-arm be two intensity modulators, this pattern can be with the synchronization of strict guarantee signal, filtering modulator 7
Two frequency components are modulated respectively in the presence of outside drive signal, factor data signal is complementary signal, therefore light
Ripple produces the flashlight of complementary intensity under the modulation of data-signal, is exactly fsk signal after coupling, FSK components in this signal
Amplitude can ensure stably, unanimously, therefore can improve transmission quality in signals transmission.
For further description FSK modulation system provided in an embodiment of the present invention, carry out below piecemeal illustrate it is each
Partial operation principle：
(1) laser and LiNbO3Modulator
Laser 2 as shown in Figure 2 and LiNbO3The fundamental diagram of modulator 4.Laser 2 is continuous light wave laser
Device, caused continuous laser can ensure the stability of luminous power.LiNbO3Modulator 4 directly connects with laser 1
Connect, continuous light wave enters LiNbO3Modulator is modulated, and is produced carrier wave and is drawn up light carrier.
LiNbO3The modulation principle of modulator 4 is as follows：
Modulator is modulated under bias voltage and driving voltage to continuous laser, and its transfer function is：
Wherein, L is insertion loss, r LiNbO3The splitting ratio of the upper and lower two-arm of modulator, ER are LiNbO3 modulators
Upper and lower two-arm extinction coefficient,The phase of respectively upper and lower arm, V1(t)、V2(t) it is respectively
The driving voltage of upper and lower two-arm, VπRF、VπDCFor LiNbO3The half-wave voltage of modulator, VB1、VB2Respectively upper and lower two-arm it is inclined
Put voltage.
In this example, r=1/2, V are madeB1=VB2=Vπ.Therefore, transfer function is changed into：
H (t)=10-L/20{1/2{exp[jπ(V1(t)+VB1)/Vπ]}
+{1/2{exp[jπ(V2(t)+VB2)/Vπ]
Make VB1-VB2=Vπ, V1(t)+V2(t)=2Vπ, then it can obtain carrier wave and draw up signal, i.e., the subcarrier that carrier wave is drawn up
Signal.
In the present invention, offset signal DC voltage control, drive signal is produced with sinusoidal signal generator；Sinusoidal signal
Generator produces the f that frequency ismSinusoidal signal is divided into two-way, is loaded directly into modulator all the way；Another way carries out back-modulation,
Cosine signal is formed to reload on modulator；Two kinds of signal loadings are to LiNbO3Modulator, lightwave signal is modulated.
Caused lightwave signal is drawn up to carrier wave, therefore there was only two subcarrier frequency (f on frequency spectrum0-fm, f0+fm), this
Caused two frequency ranges, ensure unanimously, to be easy to the stability of later stage fsk signal, this FSK on the factors such as amplitude, stability
Modulation passes through LiNbO using a laser completely3Modulators modulate come produce two carrying information light carriers, therefore this two
For individual carrier wave in addition to light frequency difference, other optical informations are identical, thus will reduce other factors (such as phase, partially
The optical information such as shake) influence for fsk signal transmission quality.
(2) modulator is filtered
The fundamental diagram of filtering modulator 7 as shown in Figure 3.This device is formed just like lower part：First coupler 71,
First Bragg grating optical fiber 72, the first intensity modulator 73, the second Bragg grating optical fiber 74, the second intensity modulator 75,
Second coupler 76.Two intensity modulators are located at respectively at the upper and lower two-arm of modulator and Striking symmetry, ensure the coupling of signal
Conjunction property, input port use Bragg grating optical fiber, complete 1:1 partial wave and the effect of filtering.Come from LiNbO3Modulator 4
Carrier wave signal of drawing up enters filtering strength modulator, and light wave is separated into oscillator intensity as 1 by input port:1 light wave, at two sections
The separation of frequency component is completed in Bragg grating optical fiber.Two subcarrier frequencies are divided into by this two sections of Bragg grating optical fibers
Two completely equivalent, the different light carrier of frequency, i.e. f0-fmSubcarrier and f0+fmSubcarrier, in order to be used in the later stage.
The operation principle of Bragg grating is：λB=2neffΛ；Wherein, λBFor reflection wavelength, neffFor having for fiber core
Refractive index is imitated, Λ is the cycle of Bragg grating.Adjust the effective refractive index of fiber core and the cycle of Bragg grating so that
The reflection wavelength of Bragg grating is equal to the wavelength (f of optical sub-carrier0-fm, f0+fm)。
Because bragg grating can be formed in an optical fiber upper set completely by optical fiber completely, therefore have and light
Fine good weldability；And manufacture craft is ripe, cost is cheap；Therefore Bragg grating optical fiber can collect well
Into being used as input optical fibre in intensity modulator, and electric level is loaded on its substrate, you can control the fibre core of Bragg grating to roll over
Rate is penetrated, and then adjusts its operation wavelength.
This modulator is formed by two intensity modulators are parallel, and intensity modulator is modulated by external data signal, outside
Portion's data-signal is divided into two-way, is loaded directly into intensity modulator all the way all the way, and entering phase inverter all the way, to be loaded into another way strong
Modulator is spent, because the amplitude that the light intensity of intensity modulator exports is modulated by external data information, due to there is the work of phase inverter
With two ways of optical signals can then produce frequency difference, the optical signal of complementary intensity, at coupler, because of the frequency of two ways of optical signals
Differ, therefore interference effect will not be produced, function only as optical signal and merge into all the way.
The operation principle of intensity modulator is：
Assuming that optical signal is：The higher subcarrier signal of upper road frequency is：eupper(t)=Amcos(ωuppert+
φupper)；Frequency relatively low subcarrier signal in lower road is：edown(t)=Amcos(ωdownt+φdown)。
Data-signal is rectangular pulse signal, it is assumed that is h (t), its value is 1 or 0；Then upper circuit-switched data signal is h'
(t), its value is then 0 or 1.
Then the optical signal after modulation is：
eupper(t)=Amh(t)cos(ωuppert+φupper)
edown(t)=Amh′(t)cos(ωdownt+φdown)
Because the frequency of two ways of optical signals is different, after coupling, light wave does not produce interference effect, is：ec(t)=Am{h
(t)cos(ωuppert+φupper)+h′(t)cos(ωdownt+φdown)}
Optical signal produces the lightwave signal of interruption with the modulation of data-signal, complementary during due to two paths of data signal, institute
It is also complementary with the signal entrained by two-way subcarrier frequency, when two-way subcarrier signal multiplex, frequency will be produced not
Disconnected change, but intensity identical fsk signal.
The fiber waveguide in two paths of data input channel is changed to bragg grating in filtering modulator, therefore not only may be used
The influence of various external factors during reducing filtered external, and to two-way light wave amplitude influences during filtered external, now by pole
The influence of big reduction FSK fsk signal dispersions in transmitting procedure caused by the amplitude difference of two frequency components, and
Due to the Striking symmetry of two-way above and below this device, stabilization and the matching of signal are also ensure that, improves the quality of fsk signal,
Improve the transmission performance of fsk signal.
Below in conjunction with the accompanying drawings and instantiation the present invention is further described.Herein by using data rate as the net of 40G/s
Lotus signal describes in detail to the present invention.
The operation wavelength of laser is 1552.5nm (i.e. 193.1THz), and with a width of 10MHz, continuous laser initially enters
LiNbO3Modulator is modulated, and is produced carrier wave and is drawn up signal, i.e. carrier wave is drawn up light wave, now only secondary carries output containing two
The light wave of ripple signal.LiNbO3Modulator for dual drive modulator, drive signal is 40G/s sine wave signal, by signal
Sine wave signal caused by generator, is loaded directly into LiNbO all the way3One drive end of modulator, another way is by reverse
Device is loaded into LiNbO3The other end of modulator；LiNbO3The half-wave voltage of modulator is 4V, then modulates LiNbO3Modulator it is inclined
Put voltage and may be controlled to upper arm and be biased to 0, underarm bias voltage is 4V, driving voltage：Upper underarm is respectively 4V and -4V；Then
Now LiNbO3Modulator exports the carrier wave that two subcarrier frequencies are 193.14THz and 193.06THz and drawn up optical signal.
By LiNbO3Caused by modulator subcarrier light wave enter filtering modulator, filtering modulator can complete partial wave,
Filtering, the function of intensity modulated.Subcarrier light wave carries out partial wave and produces amplitude ratio 1 first:1 two light waves, two paths of signals enter
Bragg grating optical fiber, this Bragg grating optical fiber are fused to intensity modulator input port, two Bragg grating light respectively
Fine center filter wavelength is respectively the wavelength of two subcarriers.Come from LiNbO3The output light-wave of modulator, is respectively enterd
Center frequency filtering is 193.06THz and 193.14THz FBG, now passes through two light waves after Bragg grating optical fiber
Frequency is respectively 193.06THz and 193.14THz, is then directly entered the light wave of the two independent frequency components follow-up strong
Spend modulator.
The two beam subcarrier optical signals for coming from Bragg grating optical fiber respectively enter two intensity modulators, intensity modulated
The modulation of device signal driven, then in the presence of additional driving, the amplitude of optical signal is changed with the fluctuation of external signal.Drive
The data-signal that dynamic signal is 40G/s, this signal represent the payload in communication network.40G/s is produced using PRBS in this example
Random signal, be then divided into two-way, all the way into the intensity modulator on upper road, enter another way intensity by phase inverter all the way
Modulator, the guarantee that this two paths of signals will be strict is synchronous into the clock of two intensity modulators, just can guarantee that two ways of optical signals
Complementary by luminous intensity caused by this two paths of data signal modulation, when producing FSK, two frequencies of guarantee is alternately present.
From modulated optical signal caused by two intensity modulators, the number of complementary intensity has been modulated in two light frequencies respectively
It is believed that number, therefore, when light frequency data all the way are " 1 ", the information entrained by another way light frequency is " 0 "；Light frequency all the way
When data are " 0 ", another way light frequency data are then " 1 ".When two-way information is coupled in coupler, then it can make two frequencies
Rate is alternately present with the form of data-signal, i.e. described fsk signal.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, all any modification, equivalent and improvement made within the spirit and principles of the invention etc., all should be included
Within protection scope of the present invention.
Claims (4)
1. a kind of FSK modulation system based on filtering modulator, it is characterised in that including sinusoidal signal generator (1), laser
(2), the first phase inverter (3), LiNbO3Modulator (4), data signal generator (5), the second phase inverter (6) and filtering modulator
(7)；
The input of first phase inverter (3) is connected to the output end of the sinusoidal signal generator (1), and described first is anti-phase
The output end of device (3) is connected to the LiNbO3The upper arm control port of modulator (4)；
The LiNbO3The input of modulator (4) is connected to the output end of the laser (2), the LiNbO3Modulator (4)
Underarm control port be connected to the output end of the sinusoidal signal generator (1)；
The input of second phase inverter (6) is connected to the output end of the data signal generator (5), and described second is anti-phase
The output end of device (6) is connected to the upper arm control terminal of the filtering modulator (7),
The input of the filtering modulator (7) is connected to the LiNbO3The output end of modulator (4), the filtering modulator
(7) underarm control port is connected to the output end of the data signal generator (5), the output of the filtering modulator (7)
Hold the output end as FSK modulation system；
The filtering modulator (7) includes the first coupler (71), the first Bragg grating optical fiber (72), the first intensity modulator
(73), the second Bragg grating optical fiber (74), the second intensity modulator (75) and the second coupler (76)；
The input of first coupler (71) is connected to the LiNbO3The output end of modulator (4), described first Prague
One end of grating fibers (72) is connected with the first output end of first coupler (71), second Bragg grating optical fiber
(74) one end is connected with the second output end of first coupler (71)；
The input of first intensity modulator (73) is connected to the other end of first Bragg grating optical fiber (72), institute
State upper arm control terminal and second phase inverter of the control terminal of the first intensity modulator (73) as the filtering modulator (7)
(6) output end connection；
The input of second intensity modulator (75) is connected to the other end of second Bragg grating optical fiber (74), institute
The control terminal for stating the second intensity modulator (75) is sent out as the underarm control terminal of the filtering modulator (7) with the data-signal
The output end connection of raw device (5)；
The first input end of second coupler (76) is connected to the output end of first intensity modulator (73), and described
Second input of two couplers (76) is connected to the output end of second intensity modulator (75), second coupler
(76) output end of the output end as the filtering modulator (7).
2. FSK modulation system as claimed in claim 1, it is characterised in that during work, laser produces continuous wave laser and entered
LiNbO3Modulator (4), LiNbO3Modulator (4) is modulated under the control of sinusoidal signal to laser signal, is produced carrier wave and is intended
Subcarrier signal processed, subcarrier signal enter filtering modulator (7), and in filtering modulator, subcarrier signal divides two-way to pass through
The upper and lower passage being made up of FBG completes the effect of carrier wave separation, and is believed in the intensity modulator in upper and lower two-arm by data
Intensity modulated is carried out in the presence of number so that the different optical signal of strength mis-matching, frequency is in filtering modulator (7) output end coupling
After export fsk signal；The sinusoidal signal is produced by sinusoidal signal generator (1), and sinusoidal signal is divided into two-way, is directly added all the way
It is loaded in the LiNbO3The underarm control terminal of modulator (4), another way reload the LiNbO after back-modulation3Modulation
The upper arm control terminal of device (4)；Data-signal is produced by data signal generator (5), and data-signal is divided into two-way, is directly added all the way
It is downloaded on filtering modulator (7) and light wave is modulated, another way reloads filtering modulation after the second phase inverter (6) is reverse
Device is adjusted on (7) to light wave.
3. FSK modulation system as claimed in claim 1, it is characterised in that the LiNbO3Modulator (4) is to the laser
(2) continuous laser of output is modulated, and its transfer function is：
<mrow>
<mi>r</mi>
<mo>=</mo>
<mrow>
<mo>(</mo>
<mn>1</mn>
<mo>-</mo>
<mn>1</mn>
<mo>/</mo>
<msqrt>
<mi>&epsiv;</mi>
</msqrt>
<mo>)</mo>
</mrow>
<mo>/</mo>
<mn>2</mn>
<mo>,</mo>
<mi>&epsiv;</mi>
<mo>=</mo>
<msup>
<mn>10</mn>
<mrow>
<mi>E</mi>
<mi>R</mi>
<mo>/</mo>
<mn>10</mn>
</mrow>
</msup>
<mo>,</mo>
</mrow>
Wherein, L is insertion loss, r LiNbO3The splitting ratio of the upper and lower two-arm of modulator (4), ER are LiNbO3 modulators (4)
Upper and lower two-arm extinction coefficient,The phase of respectively upper and lower arm, V1(t)、V2(t) it is respectively
The driving voltage of upper and lower two-arm, VπRF、VπDCFor LiNbO3The half-wave voltage of modulator, VB1、VB2Respectively upper and lower two-arm it is inclined
Put voltage.
4. FSK modulation system as claimed in claim 1, it is characterised in that in first Bragg grating optical fiber (72)
Heart filter wavelength and LiNbO3Modulator (4) output subcarrier it is Wavelength matched, bandwidth is equal.
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| CN107017953B (en) * | 2017-03-16 | 2019-10-25 | 华中科技大学 | A kind of fsk signal generation device, method and its application |
| CN113949459B (en) * | 2021-08-27 | 2022-10-21 | 西安空间无线电技术研究所 | System and method for generating photoelectric mixed FSK (frequency Shift keying) signal based on intensity modulator and MZI (Mach Zehnder interferometer) cascade |
| CN115173949A (en) * | 2022-06-09 | 2022-10-11 | 青岛农业大学 | Duty ratio adjustable rectification cosine microwave signal generator, method and equipment |
| CN116865866B (en) * | 2023-09-04 | 2023-12-05 | 湖北经济学院 | Carrier-suppressed zero-return alternating polarization/frequency shift keying quadrature modulation optical communication system |
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