CN101304156A - External cavity laser apparatus for optical fiber grating sensing system - Google Patents
External cavity laser apparatus for optical fiber grating sensing system Download PDFInfo
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- CN101304156A CN101304156A CNA2008100479222A CN200810047922A CN101304156A CN 101304156 A CN101304156 A CN 101304156A CN A2008100479222 A CNA2008100479222 A CN A2008100479222A CN 200810047922 A CN200810047922 A CN 200810047922A CN 101304156 A CN101304156 A CN 101304156A
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Abstract
The invention relates to an external cavity laser device used for a fiber grating sensor system. The device comprises a semiconductor optical amplifier 9, a Faraday rotation total-reflection mirror 6, a control circuit 8, a fiber coupler 2 and a sensory point fiber grating 4; wherein, the semiconductor optical amplifier 9 and the Faraday rotation total-reflection mirror 6 are combined into a light source 1; the Faraday rotation total-reflection mirror 6 functions as a reflecting surface of input light and meanwhile rotates the polarization state of the input light by 90 degrees and then reflects into the semiconductor optical amplifier 9 for amplification as well as compensates the polarization dependence of the semiconductor optical amplifier 9; the sensory point fiber grating 4 functions as another reflecting surface and forms a laser cavity resonator together with the Faraday rotation total-reflection mirror 6. The light source provided by the device of the invention has the advantages of high effective power of output, simple structure and strong practicality.
Description
Technical field
The present invention relates to a kind of external cavity laser apparatus that is used for fiber grating sensing system.
Background technology
In recent years, fiber grating successfully is used to different physical quantities is carried out sensing.Its outstanding advantage is a reusability, and the multiplex technique that optical fiber sensing network adopts comprises time division multiplexing, space division multiplexing, wavelength and channeling and coherent multiplexing etc.Adopt a plurality of fiber gratings, can constitute the distributed sensing network, realize that multiple spot detects, this has important use in intelligence and smart architecture.With respect to monochromatic light grid sensor-based system, multiplexing sensor-based system has advantages such as ratio of performance to price height, detection range be big, has caused people's extensive concern.By sharing light source and electron process part, along with the increase of multiplied sensor number in the system, the cost of each transducer will significantly reduce, and this will strengthen the competitiveness of Fibre Optical Sensor to traditional electrical category transducer.This multiplexing fiber-optic grating sensor is having very wide application prospect aspect the safety monitoring of large scale structure such as dam, bridge, important building and aircraft etc.
Two aspects of fiber grating sensing technology most critical are: the inquiry demodulation of light source and signal wavelength.In the multiplexing fiber-optic grating sensing system, the general light source that adopts has:
1, optical fiber amplified spontaneous emission wideband light source (ASE light source).The effective power corresponding with the fiber grating reflection peak is generally-and 15dBm is to the-25dBm, and most of spectral power is all to not contribution and having slatterned of system.This light source can only cover the 1550nm wave band at present.
2, semiconductor super-radiation light emitting diode (SLED light source).Compare with the ASE light source, the power of SLED light source is little; And the same with the ASE light source, most of spectral power is not utilized.But this light source can cover more multiband, such as communication system 850nm commonly used, 1310nm wave band and other designated band.
3, Wavelength-swept laser.This light source output wavelength can multiple scanning in a wave-length coverage, and effective power height, but complex structure cost an arm and a leg.Generally be used for than relatively large fiber grating sensing system or special sensing occasion.
In composite and distributed sensor-based system, because the optical fiber node is many, the fibre circuit loss is big, and the requirement of light source effective power is improved constantly along with the increase of sensing point.If power is too low, can influence the multiplexing quantity of sensing and the signal to noise ratio of detection, also just increased the demodulation process difficulty of signal.
Summary of the invention
The objective of the invention is in order to adapt to the higher requirement that market proposes the fiber grating sensing system light source, a kind of external cavity laser apparatus that utilizes the high reflex realization of the on-the-spot sensing point fiber grating of local gain device and distant place is provided, the feasible wavelength that swashs the just in time corresponding sensor fibre grating of penetrating of wavelength, power output height not only, and output wavelength changes and changes along with optic fiber grating wavelength, just in time can reflect the physical quantity that needs are measured, simple in structure.
Technical solution of the present invention is: a kind of external cavity laser apparatus that is used for fiber grating sensing system comprises a semiconductor optical amplifier SOA and is used to control the temperature control of SOA and the control circuit of driving, a faraday rotate completely reflecting mirror, a fiber coupler; And as the fiber grating of sensing element.Semiconductor optical amplifier and faraday rotate completely reflecting mirror and are combined as light source and are exported by output optical fibre, faraday rotates the reflecting surface of completely reflecting mirror for input light, to import polarization state of light simultaneously revolves and turn 90 degrees back reflection and advance semiconductor optical amplifier and amplify, compensation semiconductor's image intensifer polarization correlated, the sensing point fiber grating is the another one reflecting surface, rotates completely reflecting mirror with faraday and constitutes laserresonator; Fiber coupler connects semiconductor optical amplifier and fiber grating, part light is told for (FBG) demodulator analyzed.
Semiconductor optical amplifier SOA among the present invention is a device that wideband gain is provided at the fiber grating service band, it is the gain media part of this external cavity laser apparatus, the control circuit of its temperature control and driving guarantees the operate as normal of SOA, and can realize the adjusting of power output by the drive current of regulating SOA.
Faraday among the present invention rotates completely reflecting mirror, also can use the optical fiber completely reflecting mirror, and perhaps optical fiber completely reflecting mirror and Polarization Controller replace.If it is relevant that the gain that SOA provides is high polarization, then need to adopt faraday to rotate completely reflecting mirror and realize the identical amplification of SOA different polarization light, if the gain that SOA provides is that low polarization is relevant, can only use the optical fiber completely reflecting mirror.
Fiber coupler among the present invention is used for SOA and fiber grating are coupled together the formation resonant cavity, tell simultaneously a part of light as output for the (FBG) demodulator analysis.Except common fiber coupler, can also adopt the film-type optical splitter, its advantage is to reduce cavity loss, reduces the threshold value of outside cavity gas laser.
The invention has the beneficial effects as follows: the SOA that adopts band faraday to rotate completely reflecting mirror realizes the identical gain to different polarization light, can eliminate since the polarization scrambling that disturbance immediately causes in the long Distance Transmission optical fiber to the influence of laser resonance.The present invention be advantageous in that, if the fiber grating of a plurality of different wave lengths is arranged on optical fiber, if their wavelength is all in the actual gain bandwidth of SOA, swash when this external cavity laser apparatus can be realized a plurality of wavelength and penetrate, can detect the state of a plurality of optical fiber grating sensing points in other words simultaneously, realize the wavelength division multiplexing sensing.The present invention be advantageous in that the upgrading that realize old system at an easy rate can be replaced by simple light source in it and existing sensor-based system compatibility.Light source provided by the invention combines the advantage of aforementioned existing light source, not only exports the effective power height, and simple in structure, and cost is lower than Wavelength-swept laser, and is practical.Can directly replace the wideband light source on the present fiber grating sensing system and not change other system configuration.
Description of drawings
Fig. 1 is typical fiber grating sensing system schematic diagram
Fig. 2 is the Lights section structural representation of the present invention
Fig. 3 is a film-type optical splitter formation schematic diagram
Fig. 4 is the test light spectrogram of structure of the present invention
Among the figure:
1. light source, 2. fiber coupler, 3. fibre circuit, 4. fiber grating, 5. (FBG) demodulator, 6. faraday rotates completely reflecting mirror, 7. optical fiber, 8. control circuit, 9. semiconductor optical amplifier, 10. output optical fibre, 11. double-fiber collimators, 12. pellicles, 13. single fiber collimaters
Embodiment
The present invention is further described below in conjunction with accompanying drawing.
Figure 1 shows that typical fiber grating sensing system schematic diagram.General now optical fiber amplified spontaneous emission wideband light source (ASE light source) or the semiconductor super-radiation light emitting diode (SLED light source) of adopting of light source 1.Light source 1 structure of the present invention is seen Fig. 2, and semiconductor optical amplifier 9 and faraday rotate completely reflecting mirror 6 and be connected by optical fiber 7 and be combined as light source 1.Control circuit 8 makes semiconductor optical amplifier 9 that certain gain is provided for semiconductor optical amplifier 9 provides temperature control and drive current.But in optic fibre light path, because fibre circuit 3 is long, may reach tens kilometers, light polarization state inside can change at random.If the polarization degree of correlation of semiconductor optical amplifier 9 gains is too high, can cause output unstable.So we have adopted faraday to rotate completely reflecting mirror 6, it is as a reflecting surface of outside cavity gas laser on the one hand, the input polarization state of light can be revolved simultaneously and turn 90 degrees back reflection and advance semiconductor optical amplifier 9 and amplify, make that the output of laser is insensitive to the variation of polarization state in the optic fibre light path, can improve output stability greatly.Index request to semiconductor optical amplifier 9 reduces greatly simultaneously, makes cost further reduce.
In resonant cavity, adopt common 2 * 2 fiber couplers 2, because the not effect of output light of individual fiber port is arranged, bring an extra optical loss to resonant cavity, in order to improve laser output power, reduce lasing threshold, the present invention also adopts film-type optical splitter as shown in Figure 3 to replace the ordinary optic fibre coupler.This film-type optical splitter is made up of a double-fiber collimator 11, a single fiber collimater 13 and a film filtering diaphragm 12.
The fiber grating 4 that semiconductor optical amplifier 9, faraday rotate completely reflecting mirror 6, fiber coupler 2 and sensing point is operated in the identical wavelength band, is 1550nm, 1310nm wave band.We adopt the test macro as Fig. 1, are example with the 1550nm wave band.Faraday rotates polarization state of light in 6 pairs of 1550nm wave bands of completely reflecting mirror and revolves and turn 90 degrees, and the light of 9 pairs of 1550nm wave bands of semiconductor optical amplifier produces gain, and its 3dB gain bandwidth reaches 55nm.Light source output optical fibre 10 links to each other with an input arm of fiber coupler 2.Fiber grating 4 comprises 3 fiber gratings, their reflection wavelength difference, but all be positioned at the actual gain bandwidth of semiconductor optical amplifier 9.Control circuit 8 is controlled at 25 degree, operating current 150mA with semiconductor optical amplifier 9 working temperatures.Having adopted splitting ratio is 50: 50 fiber coupler 2.5 kilometers of optic fibre light path 3 length between fiber grating 4 and the fiber coupler 2.(FBG) demodulator 5 parts adopt spectrometer to carry out spectrum observation.
The spectrum that Fig. 4 obtains for test.Can see that different fiber gratings all has the corresponding sharp peak of penetrating.If the each several part in this system is optimized, gain spectral such as the splitting ratio of fiber coupler 2, semiconductor optical amplifier 9 is accurately corresponding with fiber grating 4 reflectance spectrums, reduce reflection of loss in the light path, reduction fiber end face or the like, the power of external cavity laser apparatus of the present invention can do more, more stable, fully can be under the prerequisite that does not change system's other parts structure, practical and alternative existing most of light source.Compare with other Wavelength-swept laser scheme, simple in structure and power consumption is very low, be a kind ofly can be used for long distance, the practicality of optical fiber optical grating multiplexing sensor-based system, efficient, low-cost light source.
Claims (5)
1, a kind of external cavity laser apparatus that is used for fiber grating sensing system is characterized in that this device comprises: semiconductor optical amplifier (9), faraday rotate the fiber grating (4) of completely reflecting mirror (6), control circuit (8), fiber coupler (2) and sensing point; The temperature of control circuit (8) control semiconductor optical amplifier (10) also provides drive current, semiconductor optical amplifier (9) and faraday rotate completely reflecting mirror (6) and are connected by optical fiber (7) and are combined as light source (1) and are exported by output optical fibre (10), faraday rotates the reflecting surface of completely reflecting mirror (6) for input light, to import polarization state of light simultaneously revolves and turn 90 degrees back reflection and advance semiconductor optical amplifier (9) and amplify, compensation semiconductor's image intensifer (9) polarization correlated, sensing point fiber grating (4) is the another one reflecting surface, rotates completely reflecting mirror (6) with faraday and constitutes laserresonator; Fiber coupler (2) connects semiconductor optical amplifier (9) and fiber grating (4), part light is told for (FBG) demodulator (5) analyzed.
2, external cavity laser apparatus according to claim 1 is characterized in that: fiber coupler (2) can be an optical fiber coupling film-type optical splitter.
3, external cavity laser apparatus according to claim 1, it is characterized in that: the fiber grating (4) that semiconductor optical amplifier (9), faraday rotate completely reflecting mirror (6), fiber coupler (2) and sensing point is operated in the identical wavelength band, is 1550nm, 1310nm wave band.
4, external cavity laser apparatus according to claim 1 is characterized in that: light source (1) can adopt semiconductor optical amplifier (9) and the combination of optical fiber completely reflecting mirror; Perhaps semiconductor optical amplifier (9) makes up with optical fiber completely reflecting mirror and Polarization Controller.
5, external cavity laser apparatus according to claim 2 is characterized in that: optical fiber coupling film-type optical splitter is made up of a double-fiber collimator (11), a single fiber collimater (13) and a film filtering diaphragm (12).
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2008100479222A CN101304156A (en) | 2008-06-05 | 2008-06-05 | External cavity laser apparatus for optical fiber grating sensing system |
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| CNA2008100479222A CN101304156A (en) | 2008-06-05 | 2008-06-05 | External cavity laser apparatus for optical fiber grating sensing system |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102143407A (en) * | 2010-01-29 | 2011-08-03 | 华为技术有限公司 | Method, system and device for transmitting wavelength division multiplexing passive optical network |
| CN102405607A (en) * | 2009-08-14 | 2012-04-04 | 华为技术有限公司 | Colorless dense wavelength division multiplexing transmitters |
| WO2012079412A1 (en) * | 2010-12-14 | 2012-06-21 | 华为技术有限公司 | External cavity laser and wavelength division multiplexing passive optical network system |
| CN102735274A (en) * | 2012-07-06 | 2012-10-17 | 电子科技大学 | System and method for detecting weak optical fiber sensing signals |
-
2008
- 2008-06-05 CN CNA2008100479222A patent/CN101304156A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102405607A (en) * | 2009-08-14 | 2012-04-04 | 华为技术有限公司 | Colorless dense wavelength division multiplexing transmitters |
| CN102405607B (en) * | 2009-08-14 | 2015-04-08 | 华为技术有限公司 | Colorless dense wavelength division multiplexing transmitters |
| CN102143407A (en) * | 2010-01-29 | 2011-08-03 | 华为技术有限公司 | Method, system and device for transmitting wavelength division multiplexing passive optical network |
| CN102143407B (en) * | 2010-01-29 | 2014-09-03 | 华为技术有限公司 | Method, system and device for transmitting wavelength division multiplexing passive optical network |
| WO2012079412A1 (en) * | 2010-12-14 | 2012-06-21 | 华为技术有限公司 | External cavity laser and wavelength division multiplexing passive optical network system |
| CN102735274A (en) * | 2012-07-06 | 2012-10-17 | 电子科技大学 | System and method for detecting weak optical fiber sensing signals |
| CN102735274B (en) * | 2012-07-06 | 2014-09-03 | 电子科技大学 | System and method for detecting weak optical fiber sensing signals |
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Open date: 20081112 |