CN201476800U - High-speed multi-channel fiber grating sensor demodulating system based on AWG - Google Patents
High-speed multi-channel fiber grating sensor demodulating system based on AWG Download PDFInfo
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- CN201476800U CN201476800U CN2009201537117U CN200920153711U CN201476800U CN 201476800 U CN201476800 U CN 201476800U CN 2009201537117 U CN2009201537117 U CN 2009201537117U CN 200920153711 U CN200920153711 U CN 200920153711U CN 201476800 U CN201476800 U CN 201476800U
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Abstract
The utility model discloses a high-speed multi-channel fiber grating sensor demodulating system based on arrayed waveguide grating (AWG), which comprises a light source, a fiber grating reference, a multi-channel photoswitch, an FBG probe, a dual-window AWG, a photodiode detector array, a signal amplifier, an A/D converter group and a signal demodulation processor. The system can overcome the defects of high cost, poor practicability and reliability, low resolution ratio, low demodulation speed and the like in the prior art, and can realize low cost, strong practicability, high reliability and resolution ratio, fast demodulation speed, simple structure and wide wavelength range.
Description
Technical field
The utility model relates to the optical fiber sensing technology in the communications field, particularly, relates to a kind of high-speed multiple channel fiber grating sensing demodulation system based on array waveguide grating (AWG).
Background technology
Fiber Bragg Grating FBG (Fiber Bragg Grating is called for short FBG) is a kind of Fibre Optical Sensor that produces in the later stage eighties.The sensing principle of FBG is: theoretical based on the drift of fiber grating bragg wavelength, earlier information change amount to be measured is converted into wavelength shift, and judge information change amount to be measured by the demodulation wavelength shift again, be a kind of wavelength-modulated type Fibre Optical Sensor; Compare with traditional electrical category sensor, in sensing network is used, have significant technical advantage.
But present Wavelength demodulation difficulty is big, the system cost height, and practicality is not strong; Therefore, in the sensing network application stronger, the lower-cost signal demodulation techniques of a kind of practicality need appear.Up to now, the method for many fiber grating signals demodulation has appearred, as spectrometer method, interferometric method, adjustable F-P filters demodulate method, edge filter demodulation method, the adjustable demodulation by filter method of coupling FBG etc.; Every kind of demodulation method all has its characteristics and advantage, also has many limitation.
In realizing the utility model process, the inventor finds that there are the following problems at least in the prior art:
(1) cost height: as the spectrometer method, information is clear and definite directly perceived but cost an arm and a leg;
(2) poor practicability: non-equilibrium Mach-Zehnder interferometer mode, have higher measurement sensitivity, but only be suitable for detection of dynamic, be unsuitable for detecting static amount;
(3) poor reliability, resolution are low: adjustable F-P filters demodulate method, tuning range with broad, can improve measurement range and the multiplexing number of sensing grating greatly, but because fiber F-P cavity tunable optic filter repeated bad, influence bigger the measuring accuracy of final sensing amount;
(4) demodulation speed is slow: the adjustable filtering detection method of coupling FBG, though it has high-resolution, need in the light path to use more coupling mechanism, and make system signal noise ratio lower.
Summary of the invention
The purpose of this utility model is at cost height in the prior art, poor practicability, poor reliability, resolution is low and demodulation speed is slow defective, a kind of high-speed multiple channel fiber grating sensing demodulation system based on AWG is proposed, with realize that cost is low, practical, reliability is high, resolution is high, demodulation speed is fast, simple in structure and wavelength coverage is wide.
For achieving the above object, the utility model provides a kind of high-speed multiple channel fiber grating sensing demodulation system based on AWG, comprise AWG, photodiode detector array, signal amplifier and A/D converter groups and the signal demodulation processor of light source, fiber grating benchmark, multichannel photoswitch, FBG probe, double window mouth, wherein: the exciting light signal output part of described light source is connected with the reference edge of described fiber grating benchmark and the single channel end of described multichannel photoswitch respectively; The multichannel end of described multichannel photoswitch connects with the signals collecting end of corresponding described FBG probe respectively, and simultaneously, the described single channel end of described multichannel photoswitch is connected with the signal input part of the AWG of described double window mouth; The signal output part of the AWG of described double window mouth connects with the signal input part of corresponding described photodiode detector array; The signal output part of described photodiode detector array is connected with the signal input part of A/D converter groups with described signal amplification; Described signal amplification is connected with the signal input part of described signal demodulation processor with the signal output part of A/D converter groups.
Wherein, described signal demodulation processor comprises demodulating unit and computing unit, and wherein: the difference signal input end of described demodulating unit is connected with the signal output part of A/D converter groups with described signal amplification; The difference signal output terminal of described demodulating unit is connected with the wavelength signals input end of described computing unit.
Further, this system also comprises isolator, 2 * 2 shunts and 1 * 2 shunt, wherein: the isolation signals input end of described isolator is connected with the exciting light signal output part of described light source, and the isolation signals output terminal is connected with the signal input part of described 2 * 2 shunts; The signal output part of described 2 * 2 shunts is connected with the reference edge of described fiber grating benchmark, and the reflected signal input end is connected with the single channel end of described multichannel photoswitch, and the reflected signal output terminal is connected with the signal input part of described 1 * 2 shunt; The signal output part of described 1 * 2 shunt is connected with the signal input part of the AWG of described double window mouth.
Preferably, described multichannel photoswitch is a high-speed optical switch.
Further, described FBG probe is made up of N FBG probe string that forms by the single-mode fiber serial connection.
Further, this system also comprises N FBG probe connector, first link of described N FBG probe connector and the corresponding connection of the multichannel end of described multichannel photoswitch, second link connects with the signals collecting end of FBG probe string described in the corresponding described FBG probe.
The high-speed multiple channel fiber grating sensing demodulation system of each embodiment of the utility model based on AWG, comprise light source, the fiber grating benchmark, the multichannel photoswitch, the FBG probe, the AWG of double window mouth, the photodiode detector array, signal amplifies and the A/D converter groups, and signal demodulation processor, wherein, light source can be used to produce pumping signal, the fiber grating benchmark can be used to produce wavelength standard, the multichannel photoswitch can be used for the exciting light signal of incident is carried out space division multiplexing, the FBG probe can be used to gather light intensity signal and the reflected back that is loaded with the measured physical quantity change information, the AWG of double window mouth can be used to receive the light intensity signal that FBG reflects, and realization wavelength-division multiplex, signal amplifies and the A/D converter groups can be used for narrow light belt signal that the AWG wavelength-division multiplex of double window mouth obtains and carries out signal and amplify and analog to digital conversion, and the signal demodulation processor can be used for demodulation is carried out in signal amplification and A/D converter groups, to obtain the variable quantity of the FBG probe physical quantity of being surveyed; This system can be used for the electronic surveying of some dangerous situation site environment parameters, can overcome cost height in the prior art, poor practicability, poor reliability, resolution is low, demodulation speed is slow defective, with realize that cost is low, practical, reliability is high, resolution is high, demodulation speed is fast, simple in structure and wavelength coverage is wide.
Other features and advantages of the utility model will be set forth in the following description, and, partly from instructions, become apparent, perhaps understand by implementing the utility model.The purpose of this utility model and other advantages can realize and obtain by specifically noted structure in the instructions of being write, claims and accompanying drawing.
Below by drawings and Examples, the technical solution of the utility model is described in further detail.
Description of drawings
Accompanying drawing is used to provide further understanding of the present utility model, and constitutes the part of instructions, is used from explanation the utility model with embodiment one of the present utility model, does not constitute restriction of the present utility model.In the accompanying drawings:
Fig. 1 is the theory diagram based on the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment;
Fig. 2 is the demodulation waveforms synoptic diagram based on AWG transmission spectrum and FBG reflectance spectrum in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment;
Fig. 3 be according to the utility model embodiment based on the variation diagram in two adjacency channel wavelength coverages of each comfortable AWG of single FBG wavelength in the high-speed multiple channel fiber grating sensing demodulation system of AWG;
Fig. 4 is the another theory diagram based on the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment;
Fig. 5 is the C-band spectrogram based on the AWG device of 40 passages in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment;
Fig. 6 is the C-band subwave long parameter chart based on AWG device in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment;
Fig. 7 a be according to the utility model embodiment based on one of FBG probe reflection wavelength and variation of temperature graph of a relation in the high-speed multiple channel fiber grating sensing demodulation system of AWG;
Fig. 7 b be according to the utility model embodiment based on two of FBG probe reflection wavelength and variation of temperature graph of a relation in the high-speed multiple channel fiber grating sensing demodulation system of AWG;
Fig. 8 is the L-band spectrogram based on the AWG device of 16 passages in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment.
Embodiment
Below in conjunction with accompanying drawing preferred embodiment of the present utility model is described, should be appreciated that preferred embodiment described herein only is used for description and interpretation the utility model, and be not used in qualification the utility model.
Embodiment one
According to the utility model embodiment, provide a kind of high-speed multiple channel fiber grating sensing demodulation system based on AWG.
Fig. 1 is according to the structured flowchart of the utility model based on the high-speed multiple channel fiber grating sensing demodulation system of AWG.As shown in Figure 1, present embodiment comprises: light source 301, isolator 302,2 * 2 shunts 303,1 * 2 shunt 304, fiber grating benchmark 305, multichannel photoswitch 306, FBG probe 309 and corresponding FBG probe connector, the one AWG310, the 2nd AWG311, the first photodiode detector array 312, the second photodiode detector array 313, signal amplifies and A/D converter groups 314, signal demodulation processor 315, wherein, the FBG probe is made up of N FBG probe string that forms by the single-mode fiber serial connection, and each probe was ganged up the corresponding output terminal that corresponding FBG probe connector is connected multichannel photoswitch 306; Be respectively applied for FBG probe corresponding in the corresponding output terminal that is connected multichannel photoswitch 306 and the FBG probe 309 goes here and there as a FBG probe connector 307 and N FBG probe connector 308.Here, N is a natural number.
Wherein, an AWG310 and the 2nd AWG311 form the AWG of double window mouth.
Light source 301, is connected with the input end of isolator 302 for the FBG probe produces the exciting light signal as the exciting light source of FBG probe 309.
In the present embodiment, light source 301 can be a wideband light source.
Isolator 302 can folk prescription to transmission exciting light signal, stop the light intensity signal that reflects to influence light source 301 simultaneously, the output terminal of isolator 302 is connected with the first input end of 2 * 2 shunts 303, first output terminal of 2 * 2 shunts 303 is connected with fiber grating benchmark 305, second output terminal is connected with multichannel photoswitch 306,303 pairs of exciting light signals through isolator 302 of 2 * 2 shunts carry out beam splitting, make sub-fraction exciting light signal enter fiber grating benchmark 305, thereby the sensing demodulating system that is present embodiment produces wavelength standard, and simultaneously most of exciting light signal is injected FBG probe 309 through multichannel photoswitch 306.
The exciting light signal that 306 pairs of multichannel photoswitches are injected carries out space division multiplexing, makes the sensing demodulating system physical quantity that obtains of thousands of FBG probe detections of demodulation simultaneously of present embodiment, thereby can satisfy the real-time monitoring of heavy construction sensing network.
Second input end of 2 * 2 shunts 303 is connected with the input end of 1 * 2 shunt 304, and first output terminal of 1 * 2 shunt 304 is connected with the common port of an AWG310, and second output terminal of 1 * 2 shunt 304 is connected with the common port of the 2nd AWG311; The capacity of the one AWG310 and the 2nd AWG311 is 1XN, a common port is promptly all arranged as input end and N output terminal, the light intensity signal of injecting can be divided into the arrowband of different wave length, and direct light in a plurality of photodiode detector array channels, realize wavelength-division multiplex.
Each output terminal of multichannel photoswitch 306 corresponding FBG probe connection in the FBG of correspondence probe connector and FBG probe 309 respectively; One end of each FBG probe string can be placed on the position to be measured in the physical field to be measured by the transmission cable 316 and the corresponding connection of FBG probe connector, the other end; A plurality of output terminals of the one AWG310 connect with the corresponding input end of the first photodiode detector array 312 respectively, and a plurality of output terminals of the 2nd AWG311 connect with the corresponding input end of the second photodiode detector array 313 respectively; A plurality of output terminals of the first photodiode detector array 312 and the second photodiode detector array 313 are connected with the corresponding input end of A/D converter groups 314 with the signal amplification respectively; The signal amplification links to each other with the input end of signal demodulation processor 315 with the output terminal of A/D converter groups 314.
In the present embodiment, can also comprise display device 317.Display device 317 can be connected the output terminal of signal demodulation processor 315, is used for the result of shows signal demodulation processor 315.
Use the high-speed multiple channel fiber grating sensing demodulation system based on AWG of present embodiment, FBG probe 309 is placed physical field to be measured, when certain physical quantity in the physical field to be measured changes, will cause that wave length shift takes place FBG probe 309; FBG probe 309 light intensity signals that will be loaded with this physical message reflect along original optical path, the light intensity signal of reflection is surveyed connector, multichannel photoswitch 306,2 * 2 shunts 303 and 1 * 2 shunt 304 through FBG successively, and enter the AWG of double window mouth, promptly enter an AWG310 and the 2nd AWG311 respectively; The AWG of double window mouth is divided into 2N narrow band light with the light intensity signal that reflects, the respective channel of each narrow band light difference reflected back first photodiode detector array 312 and the second photodiode detector array 313; The first photodiode detector array 312 and the second photodiode detector array 313 can be converted to electric signal by light signal with the narrow band light that reflects.
Like this, the wave length shift light intensity signal that reflects can cause the variation of light intensity signal in an AWG310 and each passage of the 2nd AWG311; The variation of light intensity signal in the one AWG310 and each passage of the 2nd AWG311, cause the rheologyization of the respective channel electric signal of the first photodiode detector array 312 and the second photodiode detector array 313, carry out the A/D conversion through signal amplification and A/D converter groups 314 respectively again, obtain corresponding digital signal; Signal demodulation processor 315 can comprise demodulating unit and computing unit, and wherein, demodulating unit calculates the wavelength shift of the light intensity signal that reflects according to this digital signal through difference; Computing unit is based on this wavelength shift, asks for the logarithm of output light wavelength ratio of the AWG adjacent light passage of double window mouth, can obtain the variable quantity of measured physical quantity.
Owing to adopt multichannel photoswitch 306 that the exciting light signal is divided into the N bundle, inject the FBG probe 309 that N FBG probe string formed respectively; Each FBG probe can be numbered in the FBG probe 309, place the position to be measured of physical field to be measured respectively, when measured physical quantity changed, wave length shift took place in corresponding FBG probe string, and the light intensity signal that will be loaded with the measured physical quantity change information reflects along original optical path; The light intensity signal that reflects enters the AWG of double window mouth, through opto-electronic conversion, signal amplification, A/D conversion and signal demodulation process, obtains the variable quantity of corresponding measured physical quantity in respective channel; Thereby can realize the high speed demodulation of a plurality of FBG probe strings.
Fig. 2 is the demodulation waveforms synoptic diagram based on AWG transmission spectrum and FBG reflectance spectrum in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment.
As shown in Figure 2, the sensing and demodulating principle of AWG is as follows: AWG is a kind of plane integrated light guide passive device, is the array waveguide grating that utilizes the slab guide technology to make on chip substrate; When AWG made demodulation multiplexer, its principle of work was: the flashlight of being made up of composite wavelength λ 1, λ 2...... λ n is coupled on the central waveguide of input waveguide and produces diffraction in the input planar waveguide, and the Gaussian beam of diffraction is coupled in the Waveguide array.Because adjacent Waveguide array is arranged with the equal length difference,, through just being focused on different output waveguide positions after the Waveguide array transmission, finished the function of demultiplexing like this so the light wave of different wave length has produced different optical path differences; When AWG made multiplexer, principle in contrast.As seen, the characteristics of AWG wavelength-division multiplex/demultiplexing and effect just in time are applicable to the demodulation of fiber grating sensing signal.
Present embodiment adopts any two adjacency channels of double window mouth AWG to come fiber grating sensing signal of demodulation, and this fiber grating sensing signal variation range is between the centre wavelength of two adjacency channels of AWG.
For capacity is the AWG of 1XN, and the narrow band light that the incident light in any frequency range can be divided into different wave length imports in a plurality of passages, realizes wavelength-division multiplex.In actual applications, the centre wavelength of each FBG probe string can be defined as 1-N, each FBG probe grating is corresponding with two adjacency channels of AWG, FBG probe grating wavelength changes with tested parameter such as temperature or stress etc., and variation range is between the centre wavelength of two adjacent channels of AWG.
Fig. 3 be according to the utility model embodiment based on the variation diagram in two adjacency channel wavelength coverages of each comfortable AWG of single FBG wavelength in the high-speed multiple channel fiber grating sensing demodulation system of AWG.
As shown in Figure 3, when the FBG reflected light wavelength that is loaded with heat transfer agent during by two adjacent optical channels, because the feature difference of channel, the light feature of output is also different, in theory output spectrum equal defeated people's spectrum and the convolution by channel characteristics.
The logarithm of the output ratio of adjacent two passages of AWG can be defined as demodulation function, that is:
λ wherein
BiIt is the reflection wavelength of i FBG.The transmission spectrum of FBG reflectance spectrum and AWG passage all can be approximated to be Gaussian function, and the lap of FBG reflectance spectrum and AWG passage transmission spectrum has determined the size of AWG passage output intensity.AWG adjacency channel intensity rate logarithm and FBG wavelength are linear under Gaussian approximation.
Obviously, the output valve of adjacent two passages of AWG can be by measuring, and the data processing by the later stage can obtain wavelength value again.The principle of array waveguide grating AWG wavelength detection that Here it is.
The FBG probe can be installed on testee and material internal, various physical quantitys such as osmotic pressure, temperature, stress, strain, flow velocity, flow are detected, when causing a FBG probe surrounding environment part to change owing to various factor, to cause FBG reflection wavelength displacement λ, by monitoring these spectrum change situations, can obtain the changing condition of measurand, reach testing goal.
Embodiment two
Fig. 4 is according to the another structured flowchart of the utility model based on the high-speed multiple channel fiber grating sensing demodulation system of AWG.
As shown in Figure 4, present embodiment comprises: light source 601, isolator 602,2 * 2 shunts 603,1 * 2 shunt 604, fiber grating benchmark 605, multichannel photoswitch 606, FBG probe 609 and corresponding FBG probe connector, an AWG610, the 2nd AWG611, the first photodiode detector array 612, the second photodiode detector array 613, signal amplify and A/D converter groups 614, signal demodulation processor 615 and display screen 617.
Wherein, light source 601, isolator 602 and 603 unidirectional connections of 2 * 2 shunts, the output terminal of 2 * 2 shunts 603 is connected with the input end of fiber grating benchmark 605 with 1 * 8 road photoswitch 606 respectively, the output terminal of 1 * 8 road photoswitch 606 respectively in a FBG probe connector 607 to the 8th FBG probe connectors 608 and FBG probe 609 corresponding FBG probe contact and connect.Here, the FBG probe connector connects by transmission cable 616 and FBG probe polyphone.
AWG-C610 and AWG-L611 will reflex to the narrow band light that wherein light intensity signal is divided into 2N different wave length respectively, and import to the respective channel of the first photodiode detector array 612 and the second photodiode detector array 613, through opto-electronic conversion, the electric signal that obtains imports to the respective channel of signal amplification and A/D converter groups 614, amplify and the A/D conversion through signal, obtain corresponding digital signal, again through signal demodulation processor 615, through the signal demodulation process, obtain the variable quantity of corresponding measured physical quantity, and show measurement result by display screen 617.
In the present embodiment, the effect of each components and parts can be referring to the related description of Fig. 1.The AWG type Wavelength division multiplexer/demultiplexer spare of double window mouth is used for the demodulation transducing signal, specific practice: the FBG probe is placed physical field to be measured, when the physical quantity in the physical field to be measured changes, FBG probe is subjected to that this physical quantity changes influences the generation wave length shift, can detect the size of the wavelength shift that demodulates the FBG probe by this high-speed multiple channel fiber grating sensing demodulation system based on AWG; According to the size of this wavelength shift,, can obtain the variable quantity of measurand by calculating.
In the present embodiment, signal demodulation processor 615 can comprise demodulating unit and computing unit, and wherein, demodulating unit is used for the digital signal according to 614 outputs of A/D converter groups, carries out difference and calculates, and obtains the wavelength shift of the light intensity signal that reflects; Computing unit is used for according to wavelength shift, asks for the logarithm of output light wavelength ratio of the AWG adjacent light passage of double window mouth, can obtain the variable quantity of measured physical quantity.
In the various embodiments described above, with two two windows that are operated in C-band and L-band respectively, the AWG type Wavelength division multiplexer/demultiplexer that coincides of window edge is used for the demodulation transducing signal simultaneously, that is: AWG can select C-band, L-band or C+L wave band respectively according to application need, realize the demodulation of wide region multi-wavelength, make Wavelength demodulation range spans C-band, L-band, surpass more than the 80nm based on the high-speed multiple channel fiber grating sensing demodulation system of AWG.
The receiver function of each passage of AWG or transmission spectrum adopt Gaussian respectively, adopt fiber grating sensing signal of two adjacency channel demodulation, the centre wavelength of every string FBG probe is defined as 1-N, they are with tested parameter such as temperature or STRESS VARIATION, and variation range is between the centre wavelength of two adjacent channels of AWG; When the FBG reflected light wavelength that is loaded with heat transfer agent passed through adjacent optical channel, the logarithm that can define the output ratio of adjacent two passages of AWG was a demodulation function.
Above-mentioned wideband light source can adopt the wide range LASER Light Source of C-band, L-band or C+L wave band, and the Wavelength demodulation scope of system is reached more than the 80nm.
The AWG that is operated in C-band and two windows of L-band respectively and the output wavelength of the 2nd AWG are carried out code detection, to determine the position of sensing point probe; When system connects multifiber simultaneously, but every optical fiber many FBG sensors of wavelength-division multiplex again make and satisfy the real-time monitoring of heavy construction sensing network by thousands of FBG sensors of system's demodulation simultaneously.
In addition, the multichannel photoswitch in the various embodiments described above all can adopt high-speed optical switch.
Embodiment three
In the present embodiment, light source 601 can be that spectral range is the C-band wideband light source of 1527～1562nm; The splitting ratio of 2 * 2 shunts 603 can be 10: 90; 1 * 2 shunt 604 can be the coupling mechanism of 3db, and its splitting ratio is 50: 50; FBG probe 609 can comprise the FBG temp probe of two series connection; AWG can comprise 40 output channels, and spectral range is 1528.55～1560.61nm, channel spacing 100GHz/0.8nm, Gaussian distribution, 1dB channel bandwidth 0.24nm, 3dB channel bandwidth 0.40nm, Insertion Loss 5.36～6.28dB, the adjacency channel 32.56～37.20dB that crosstalks; A/D converter groups 614 can be the MCU single-chip microcomputer.
Fiber grating benchmark 605 is placed constant temperature oven, and the constant temperature precision is 0.1 ℃.In order to improve system's degree of accuracy and resolution, fiber grating benchmark 605 can adopt cuts the toe fiber grating.
Fig. 5 is the C-band spectrogram based on the AWG device of 40 passages in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment, and Fig. 6 is the C-band subwave long parameter chart based on AWG device in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment.
As shown in Figure 5 and Figure 6, the centre wavelength of two FBG temp probes of present embodiment is respectively: λ 1=1534.6401nm, λ 2=1536.9850nm, spacing is 2.3449, wherein: λ 1=1534.6401nm, between the 6-7 passage of the array waveguide grating AWG of 40 passages, λ 2=1536.9850nm is between the 9-10 passage of the array waveguide grating AWG of 40 passages.The precision of photodiode detector is 0.001dBm.
According to experiment value, the standard deviation of temperature and wavelength is respectively 0.05 ℃ and 0.5pm in 2h, maximum drift range about 0.18 ℃ and 2pm.
Fig. 7 a be according to the utility model embodiment based on one of FBG probe reflection wavelength and variation of temperature graph of a relation in the high-speed multiple channel fiber grating sensing demodulation system of AWG; Fig. 7 b be according to the utility model embodiment based on two of FBG probe reflection wavelength and variation of temperature graph of a relation in the high-speed multiple channel fiber grating sensing demodulation system of AWG.
Shown in Fig. 7 a and Fig. 7 b, crosstalking between the FBG has some influences to demodulating system, comes down to because the variation of crosstalking will cause interference to the detection light intensity of adjacent fiber Bragg grating demodulation passage, thereby produces the demodulation measuring error.Measured FBG2 in the example and changed,, crosstalking of its adjacent FBG1 demodulation passage changed and the sensing measurement error as 25 ℃ to 105 ℃ because of sensing temperature.Obtain the FBG2 variation range that changes the AWG binary channels strength ratio (being logarithm value) that causes the FBG1 correspondence of crosstalking and be-0.382～0.244dBm, the corresponding standard deviation is 0.126dB, in conjunction with the sensitivity of system wavelength that records and temperature, the standard deviation that calculates wavelength and temperature is 2pm.
Embodiment four
Each components and parts and annexation thereof can be referring to embodiment two in the present embodiment.
Concrete, in the present embodiment, comprising: C+L wave band wideband light source, spectral range are 1528～1601nm; The splitting ratio of 2 * 2 shunts is 10: 90; 1 * 2 shunt can be the 3db coupling mechanism, and splitting ratio is 50: 50; A series connection FBG osmotic pressure sensing probe, range is 250kPa; The AWG of one 16 passage, spectral range is 1574.213～1599.541nm, adopts Gaussian distribution, spectral range channel spacing 50GHz/1.5nm, 1dB channel bandwidth 0.420nm, 3dB channel bandwidth 0.640nm, Insertion Loss 5.56～6.68dB, the adjacency channel 32.16～37.70dB that crosstalks.
In the present embodiment, employing MCU single-chip microcomputer replaces the A/D converter groups among above-mentioned Fig. 1 or Fig. 4.
Fig. 8 is the L-band spectrogram based on the AWG device of 16 passages in the high-speed multiple channel fiber grating sensing demodulation system of AWG according to the utility model embodiment.
As shown in Figure 8, the FBG osmotic pressure sensing probe range that present embodiment adopts is 250kPa, corresponding 25 meters liquid level ranges, two FBG are arranged in this osmotic pressure sensing probe, a strain grating, a temperature compensation grating, its centre wavelength is respectively: λ 1=1576.541nm, λ 2=1582.522nm.Wavelength spacing 5.981nm, λ 1=1576.541nm in the osmotic pressure sensing probe, between the 2-3 passage of the AWG of 16 passages, λ 2=1582.522nm, between the 6-7 passage of the AWG of 16 passages, the range of control of liquid level developmental tube is 0.5m～2m, the about 2mm of liquid level maximum drift range in the 1.5m scope.
The precision of photodiode detector is 0.001dBm.
According to experiment value, the standard deviation of present embodiment respective wavelength is 2pm, and the about 2cm of liquid level maximum drift range is better than 2/1000ths of total range.
In each embodiment of the utility model, external communication interface can be set, for example RS232/RS485, USB and RJ45 etc., the user can select corresponding interface, carries out interface management, sets up communication contact with host computer, accept the order that host computer is sent from communication interface, the heat transfer agent of each passage in the host computer transmitting system, warning message exposes by the operating point to the corresponding port and to answer the pilot lamp of passage.
Use the high-speed multiple channel fiber grating sensing demodulation system of each embodiment of the utility model based on AWG, can adopt electronically to measure as the parameter measurement of site environment is monitored, realized to light signal to conversion, the demodulation of optical wavelength signal, the pre-alarm of electric signal to the parameter of some dangerous situations, security be higher.
Each embodiment of the utility model is used for AWG type Wavelength division multiplexer/demultiplexer spare the demodulation of transducing signal, similar one based on the quasi-distributed FBG of array waveguide grating intensity demodulation technology at a high speed, high-precision sensor, have advantages such as structure is simple relatively, cost is low, wavelength resolution is high, demodulation speed is fast, use is stable; In addition, adopt Wavelength-encoding technology, wavelength-division multiplex technique to realize distributed, large-capacity fiber grating sensing demodulation, made full use of resource, guaranteed the reliability requirement of system.
In sum, the high-speed multiple channel fiber grating sensing demodulation system of each embodiment of the utility model based on AWG, comprise light source, isolator, 2 * 2 shunts, 1 * 2 shunt, the fiber grating benchmark, the multichannel photoswitch, the FBG probe connector, the FBG probe, the AWG of double window mouth, the photodiode detector array, signal amplifies and the A/D converter groups, and signal demodulation processor, the AWG type Wavelength division multiplexer/demultiplexer spare of double window mouth can be used for the demodulation of transducing signal, the FBG probe can be placed physical field to be measured, when measured physical quantity changes, the light intensity signal that the FBG probe can will be loaded with the measured physical quantity change information reflects by original optical path, the light intensity signal that reflects is divided into the narrow band light of different wave length through the AWG of double window mouth, again with each narrow band light through opto-electronic conversion, signal amplifies and the A/D conversion, obtain corresponding wavelength shift, ask for the value of demodulation function again based on the wavelength shift that obtains, can obtain the variable quantity of corresponding measured physical quantity; AWG does not also have more than 100 more today of hyperchannel technology, adopt the AWG concurrent working of double window mouth, wherein an AWG is operated in C-band, and the 2nd AWG is operated in L-band, and the edge of two wave bands coincides, and can realize the wide wavelength range demodulation of C+L wave band; The centre wavelength that per two adjacency channels of AWG can a corresponding sensing probe simultaneously, the size of the signal wavelength that the reaction of the size of light intensity is passed through in each passage, compared with prior art, have that cost is low, practical, reliability is high, resolution is high, demodulation speed is fast, simple in structure and advantage that wavelength coverage is wide.
It should be noted that at last: the above only is preferred embodiment of the present utility model, be not limited to the utility model, although the utility model is had been described in detail with reference to previous embodiment, for a person skilled in the art, it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement.All within spirit of the present utility model and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within the protection domain of the present utility model.
Claims (6)
1. high-speed multiple channel fiber grating sensing demodulation system based on array waveguide grating AWG, it is characterized in that, AWG, photodiode detector array, signal amplifier and the A/D converter groups and the signal demodulation processor that comprise light source, fiber grating benchmark, multichannel photoswitch, FBG probe, double window mouth, wherein:
The exciting light signal output part of described light source is connected with the reference edge of described fiber grating benchmark and the single channel end of described multichannel photoswitch respectively;
The multichannel end of described multichannel photoswitch connects with the signals collecting end of corresponding described FBG probe respectively, and simultaneously, the described single channel end of described multichannel photoswitch is connected with the signal input part of the AWG of described double window mouth;
The signal output part of the AWG of described double window mouth connects with the signal input part of corresponding described photodiode detector array;
The signal output part of described photodiode detector array is connected with the signal input part of A/D converter groups with described signal amplification;
Described signal amplification is connected with the signal input part of described signal demodulation processor with the signal output part of A/D converter groups.
2. the high-speed multiple channel fiber grating sensing demodulation system based on AWG according to claim 1 is characterized in that described signal demodulation processor comprises demodulating unit and computing unit, wherein:
The difference signal input end of described demodulating unit is connected with the signal output part of A/D converter groups with described signal amplification;
The difference signal output terminal of described demodulating unit is connected with the wavelength signals input end of described computing unit.
3. the high-speed multiple channel fiber grating sensing demodulation system based on AWG according to claim 1 is characterized in that this system also comprises isolator, 2 * 2 shunts and 1 * 2 shunt, wherein:
The isolation signals input end of described isolator is connected with the exciting light signal output part of described light source, and the isolation signals output terminal is connected with the signal input part of described 2 * 2 shunts;
The signal output part of described 2 * 2 shunts is connected with the reference edge of described fiber grating benchmark, and the reflected signal input end is connected with the single channel end of described multichannel photoswitch, and the reflected signal output terminal is connected with the signal input part of described 1 * 2 shunt;
The signal output part of described 1 * 2 shunt is connected with the signal input part of the AWG of described double window mouth.
4. the high-speed multiple channel fiber grating sensing demodulation system based on AWG according to claim 1 is characterized in that described multichannel photoswitch is a high-speed optical switch.
5. according to each described high-speed multiple channel fiber grating sensing demodulation system among the claim 1-4, it is characterized in that described FBG probe is made up of N FBG probe string that forms by the single-mode fiber serial connection based on AWG.
6. the high-speed multiple channel fiber grating sensing demodulation system based on AWG according to claim 5, it is characterized in that, this system also comprises N FBG probe connector, first link of described N FBG probe connector and the corresponding connection of the multichannel end of described multichannel photoswitch, second link connects with the signals collecting end of FBG probe string described in the corresponding described FBG probe.
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