CN102494701A - Wavelength demodulating system for signal enhancement type fiber bragg grating (FGB) sensor - Google Patents
Wavelength demodulating system for signal enhancement type fiber bragg grating (FGB) sensor Download PDFInfo
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- CN102494701A CN102494701A CN2011103967319A CN201110396731A CN102494701A CN 102494701 A CN102494701 A CN 102494701A CN 2011103967319 A CN2011103967319 A CN 2011103967319A CN 201110396731 A CN201110396731 A CN 201110396731A CN 102494701 A CN102494701 A CN 102494701A
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Abstract
The invention provides a wavelength demodulating system for a signal enhancement type fiber bragg grating (FGB) sensor. The system comprises a light source part, a signal detection part and a control circuit part, wherein a reflected light signal of the fiber bragg grating (FGB) sensor reversely passes through a light path of the light source part to be amplified by the wavelength demodulating system; reflected light and incident light of the light source part are separated by a wavelength multiplexer; and output light strength and reflected light strength are simultaneously monitored by a 2*2 light energy distributor. The wavelength demodulating system provided by the invention has the advantages that: the system detection flexibility can be improved by detecting the amplified signal of the fiber bragg grating (FGB) sensor; the reflected light and the incident light are separated by the wavelength multiplexer without a circulator; and the system has laser safety alarm and protection functions.
Description
Technical field
The present invention relates to sensory field of optic fibre, relate in particular to a kind of signal enhanced fiber Bragg grating (FBG) Wavelength demodulation system.
Background technology
Fiber Bragg Grating FBG (FBG) sensor is widely used in engineering fields such as the energy, traffic, building, advantages such as having the irreplaceable anti-electromagnetic interference (EMI) of ordinary electronic sensor, detect distance, be safe and reliable.Fiber Bragg Grating FBG (FBG) sensor is to utilize grating reflection signal center wavelength to detect the physical change of tested target along with the characteristic of environmental factors such as temperature, stress change.Common Wavelength demodulation system has scanning tunable laser scheme and scanning narrow band filter scheme.In scanning tunable laser scheme, generally adopt synchronized sampling laser instrument and sensor output signal, utilize the peak detection method to realize the demodulation of centre wavelength signal.This scheme high speed tunable laser is very expensive, is not easy to a large amount of uses.In scanning narrow band filter scheme; The light signal that generally wideband light source is produced passes through the optical fiber of circulator incoming fiber optic Bragg grating (FBG) sensor, and the light signal that reflects from Fiber Bragg Grating FBG (FBG) sensor is coupled to the wavelength pick-up unit based on the adjustable narrow-band wave filter through circulator.Wideband light source and circulator all are expensive optical devices in this system; And along with sensor cascade quantity increases; Dispose after the distance lengthening, cause signal can't detect or need high, expensive photodetector of sensitivity and complex detection circuit design from the light signal strength of Fiber Bragg Grating FBG (FBG) reflection is low excessively.
Summary of the invention
In order to solve the problems of the technologies described above, the present invention provides a kind of signal enhanced fiber Bragg grating (FBG) sensor wavelength demodulating system, and this system comprises the Lights section, input part and control circuit part.This system need not special-purpose wideband light source and circulator essential in common Wavelength demodulation system, and can amplifying fiber Bragg grating (FBG) light signal of reflection, improve detection sensitivity, increase system sensor cascade quantity, and improve detection range greatly.
As optional technical scheme, said the Lights section comprises pump laser, optical wavelength multiplexing device, Er-doped fiber, GFF, optoisolator, 2x2 luminous energy divider and photodetector (PD).Said optical wavelength multiplexing device is 980nm pumping laser and C-band photo-coupler, can the light of 980nm wavelength perhaps be separated with the optically-coupled of C-band.Said pump laser produces the laser of 980nm wavelength through said wavelength multiplexer input gain medium Er-doped fiber, and white hair radiation (ASE) spectrum that the Er-doped fiber generation is amplified exports external fiber Bragg grating (FBG) sensor to through the output terminal of 2x2 luminous energy divider.The peak wavelength light signal that reflects from external fiber Bragg grating (FBG) sensor obtains amplifying through Er-doped fiber in the other direction.
As optional technical scheme, said photodetector (PD) can detect output intensity and reflective light intensity respectively, is used for light stability control and laser safety alarm.
As optional technical scheme, said input part is made up of luminous-power distributor, tunable optical filter, wavelength reference Fabry-Perot etalon (F-P Etalon), photodetector (PD).Spectral signal inserts tunable optical filter, and output light is divided into two-way through luminous-power distributor and detects light intensity, and one the tunnel directly gets into photodetector (PD), and another road gets into photodetector (PD) through wavelength reference Fabry-Perot etalon (F-P Etalon).In the adjustable filter scanning wavelength; On two-way photodetector (PD), adopt the clock signal that can obtain Fiber Bragg Grating FBG (FBG) signal and reference wavelength simultaneously, the control circuit part can be recovered Fiber Bragg Grating FBG (FBG) wavelength peak signal according to certain algorithm through reference wavelength then.
As optional technical scheme; Control circuit partly is specially hardware and software platform, but the pump laser of light source support part drives output and reflective light intensity monitoring; The laser safety alarm; Adjustable filter drives, and Fiber Bragg Grating FBG (FBG) signal and reference wavelength signals collecting and analog to digital conversion, wavelength recovery algorithms etc.
The invention has the advantages that: through the special light sources partial design; Can make the light signal that reflects from Fiber Bragg Grating FBG (FBG) sensor obtain amplifying through the gain media of the Lights section; Improve the sensitivity of input, reduce detector hardware performance and testing circuit designing requirement, and in this design; Need not to re-use cost an arm and a leg broadband laser source and circulator, reduce system cost.
Description of drawings
It shown in the accompanying drawing 1 the system architecture synoptic diagram of embodiment of the present invention.
Embodiment
Embodiment below in conjunction with 1 pair of signal enhanced fiber Bragg grating provided by the invention of accompanying drawing (FBG) sensor wavelength demodulating system elaborates.
Be the structural representation of the described signal enhanced fiber of this embodiment Bragg grating (FBG) sensor wavelength demodulating system shown in the accompanying drawing 1, comprise the Lights section, the input part, the control circuit part, back literary composition will be described in detail individual part.
The Lights section embodiment for example the Lights section comprises pump laser (LD) 11, wavelength multiplexer one (WDM1) 12, Er-doped fiber one (EDF1) 13, wavelength multiplexer two (WDM2) 14, GFF (GFF) 15, wavelength multiplexer three (WDM3) 16, Er-doped fiber two (EDF2) 17,2x2 optical energy divider (Coupler) 18, photodetector one (PD1) 111, photodetector two (PD2) 110 and isolator (Isolator) 19.Pump laser (LD) is used to produce the pumping laser of 980nm wavelength; Wavelength multiplexer one (WDM1) 12 imports Er-doped fiber one (EDF1) 13 with pumping laser from port one 2a coupling; The residue pumping laser separates the output from port one 4a with C-band amplified spont-aneous emission (ASE) light in the Er-doped fiber one (EDF1) 13 in wavelength multiplexer two (WDM2) 14, is coupled into Er-doped fiber two (EDF2) 17 through wavelength multiplexer three (WDM3) 16 port one 6a then.C-band amplified spont-aneous emission (ASE) light is along the path transmission of Er-doped fiber one (EDF1) 13, wavelength multiplexer two (WDM2) 14, GFF (GFF) 15, wavelength multiplexer three (WDM3) 16, and the output terminal 18a through 2x2 optical energy divider (Coupler) 18 exports external fiber Bragg grating (FBG) sensor at last.
External fiber Bragg grating (FBG) sensor embodiment can be Fiber Bragg Grating FBG (FBG) sensor optical path of cascade; Be incident to Fiber Bragg Grating FBG (FBG) sensor optical path of cascade from white hair radiation (ASE) light wave of the amplification of 2x2 optical energy divider (Coupler) port one 8a output; Each Fiber Bragg Grating FBG (FBG) sensor all can reflect the signal of a certain wavelengths, so can receive a series of wavelength peak signals that have that Fiber Bragg Grating FBG (FBG) sensor reflects at the 18a of 2x2 optical energy divider (Coupler) end.These flashlights export the input part to through wavelength multiplexer three (WDM3) 16, Er-doped fiber two (EDF2) 17, GFF (GFF) 15, wavelength multiplexer two (WDM2) 14, Er-doped fiber one (EDF1) 13, wavelength multiplexer one (WDM1) 12, isolator (Isolator) 19; Signal can be exaggerated in the process through Er-doped fiber two (EDF2) and Er-doped fiber one (EDF1), so this embodiment can realize the enhancing of Fiber Bragg Grating FBG (FBG) sensor signal.
2x2 optical energy divider (Coupler) 18 embodiments can adopt but be not limited to 98% to 2% splitting ratio, and port one 8a and 18c are 98% end, and 18b and 18d are 2% end.18b end is told 2% Output optical power and is sent into photodetector one (PD1) 111 and be used for light source power control, and the 18d end is told 2% reflected optical power and sent into photodetector two (PD2) 110 monitoring reflective light intensities and be used to realize the laser safety alarm.Laser safety alarm embodiment; For example connect external sensor optical fiber state, should be lower than-20dB under the ratio normal condition of reflective light intensity and output intensity, when 18a is in off-state when the output terminal 18a of 2x2 optical energy divider (Coupler) 18 is in; Interface at air and optical fiber can form reflecting surface; Reflected light can be higher than-17dB with the ratio of output light, as the laser safety alarm threshold is set is-18dB, then when 18a is in off-state the control electric circuit inspection to reflective light intensity and output intensity ratio above-17dB; Promptly can trigger alarm; System can close or reduces pump laser 11 according to alarm status, and the system output power of making is reduced to security level, guarantees operating personnel and system device safety.
Input part embodiment for example input part is made up of adjustable filter 21, luminous-power distributor 22, wavelength reference Fabry-Perot etalon (F-P Etalon) 23, photodetector three (PD3) 24, photodetector four (PD4) 25.Concrete working method is to scan the spectrum that constitutes from the flashlight and the reverse amplified spont-aneous emission (ASE) of the Lights section reflection with adjustable filter; Filtering signal is divided into two-way through luminous-power distributor detects light intensity; One the road inserts your detector three (PD3) 24 of light belt, and photodetectors four (PD4) 25 are inserted through Fabry-Perot etalon (F-P Etalon) 23 in another road.In adjustable filter 21 scanning wavelengths; Sampling simultaneously can obtain the clock signal of Fiber Bragg Grating FBG (FBG) signal and reference wavelength on the two-way photodetector, and the control circuit part can be recovered Fiber Bragg Grating FBG (FBG) wavelength peak signal through certain algorithm according to reference wavelength then.
Control circuit part embodiment is printed circuit-board assembly (PCBA) 31 for example.But the pump laser of the hardware and software platform light source support of this printed circuit-board assembly part drives; Output and reflective light intensity monitoring, the laser safety alarm, adjustable filter drives; Fiber Bragg Grating FBG (FBG) signal and reference wavelength signals collecting and analog to digital conversion, wavelength recovery algorithms etc.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and evolution, these improvement and evolution also should be regarded as protection scope of the present invention.
Claims (5)
1. a signal enhanced fiber Bragg grating (FBG) sensor wavelength demodulating system is characterized in that:
Utilize the Lights section light path that the light signal of Fiber Bragg Grating FBG (FBG) sensor reflection is amplified;
Adopt wavelength multiplexer that reflected light is separated with incident light;
Have laser safety alarm and defencive function.
2. signal enhanced fiber Bragg grating according to claim 1 (FBG) sensor wavelength demodulating system; It is characterized in that; The Er-doped fiber that said the Lights section design makes Fiber Bragg Grating FBG (FBG) sensor signal can oppositely pass through amplified spont-aneous emission (ASE) light source amplifies enhancing signal detection sensitivity.
3. signal enhanced fiber Bragg grating according to claim 1 and 2 (FBG) sensor wavelength demodulating system; It is characterized in that; The Lights section design adopts wavelength multiplexer that white hair radiation (ASE) light source light spectrum of the amplification of the signal spectrum of reverse transfer and forward transmitted is separated, and need not to use the circulator separation signal.
4. signal enhanced fiber Bragg grating according to claim 1 (FBG) sensor wavelength demodulating system is characterized in that, adopts 2x2 luminous energy dispensing arrangement can monitor output intensity and reflective light intensity simultaneously, realizes the laser safety alarm.
5. signal enhanced fiber Bragg grating according to claim 1 (FBG) sensor wavelength demodulating system is characterized in that, the control circuit part can initiatively be closed pump laser source and realized laser safeguard protection when detecting the laser safety alarm.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104375148A (en) * | 2014-11-14 | 2015-02-25 | 上海理工大学 | Near-infrared laser ranging method based on linear sensitive photon detector |
| CN107329162A (en) * | 2017-08-04 | 2017-11-07 | 上海交通大学 | Gamma radiation real-time measurement apparatus and its system based on Bragg grating |
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2011
- 2011-12-02 CN CN2011103967319A patent/CN102494701A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104375148A (en) * | 2014-11-14 | 2015-02-25 | 上海理工大学 | Near-infrared laser ranging method based on linear sensitive photon detector |
| CN104375148B (en) * | 2014-11-14 | 2017-01-18 | 上海理工大学 | Near-infrared laser ranging method based on linear sensitive photon detector |
| CN107329162A (en) * | 2017-08-04 | 2017-11-07 | 上海交通大学 | Gamma radiation real-time measurement apparatus and its system based on Bragg grating |
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Application publication date: 20120613 |