CN1664517A - Dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity - Google Patents
Dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity Download PDFInfo
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- CN1664517A CN1664517A CN 200510024484 CN200510024484A CN1664517A CN 1664517 A CN1664517 A CN 1664517A CN 200510024484 CN200510024484 CN 200510024484 CN 200510024484 A CN200510024484 A CN 200510024484A CN 1664517 A CN1664517 A CN 1664517A
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Abstract
The invention relates to a device for detecting the total optical fiber absorbing spectrum, which comprises an illuminating source, the first driver, an optical cavity, a light-sensitive detector, and a signal collecting and processing system connected together. The device has the merits as follows: the reflectance of the cavity is high, the fineness of the resonant cavity is high, the reflection bandwidth and spectral measuring range are wide, the luminous power couple is efficiency, the measuring sensibility is high and the structure is simple.
Description
Technical field
The present invention a kind ofly adopts the chamber to decline to swing the optical fiber of principle to detect sensing technology.The invention belongs to the optical measurement field of sensing technologies, be mainly used in physical quantity and the chemical sensing detection of measuring such as liquid, gas concentration and refractive index such as strain, pressure, electric current.
Background technology
Fibre Optical Sensor is owing to have that anti-electromagnetic interference capability is strong, highly sensitive, electrical insulating property is good, safe and reliable, corrosion-resistant, can constitute plurality of advantages such as optical fiber sensor network, thereby in each fields such as industry, agricultural, biologic medical, national defence broad prospect of application arranged all.
Cavity ring-down spectroscopy technology (Cavity Ring Down Spectroscopy) be grew up in recent years the novel detection technique of a kind of absorption spectrum.Cavity ring-down spectroscopy technology ultimate principle is: the high-fineness optical resonator of being made up of two high reflection mirrors (usually, reflectivity R 〉=0.9999 of high reflection mirror), sub-fraction (1-R, about 10 are incided in the measuring light pulse
-5) incident light be coupled into optical resonator by one of them high reflection mirror, in the chamber, come back reflective, in chamber mirror reflection loss, chamber in inherent loss and the chamber under the effect of measured matter (as chemical absorbing bodies such as gas, liquid) absorption loss, in the chamber photon number back and forth the vibration in slowly the decay (promptly decline and swing, ringdown).In the chamber light pulse whenever back reflective once, sub-fraction (1-R, about 10
-5) photon transfers to outside the chamber and by a high sensitivity photodetector by Effect of Back-Cavity Mirror and surveys in the chamber, the output of detector will present exponential damping, and its timeconstant is decided by the absorption size of the reflectivity and the measured matter of chamber mirror, as shown in Equation 1,
In the formula, L is the optical resonance cavity length, n
EffBe effective refractive index in the chamber, R is the reflectivity of chamber mirror, and l is the absorption loss that measured matter causes in the chamber.By the time constant of measuring light decay, survey the absorption size of measured matter thus, and and then can obtain its concentration according to the specific reason of lambert Bill, as formula 2
l＝αL＝σLC (2)
Here, α is the absorption coefficient of measured matter, and σ is the absorption cross section of measured matter, and C is the concentration of measured matter.
The major advantage of cavity ring-down spectroscopy technology is: 1. adopt the high-fineness optical resonator, greatly increased the absorption light path, improved the sensitivity of measuring greatly; 2. by measuring the damping time constant of pulse in the chamber, insensitive to the input light-intensity variation, be a kind of direct measurement to cavity loss, need not the conversion calibration.
For the cavity ring-down spectroscopy principle is introduced in the sensory field of optic fibre, in conjunction with both advantages, decline and swing sensing technology in formation novel optical fiber chamber, and people have proposed some technical schemes.One of technology [Tuomo von Lerber etc. formerly, APPLIED OPTICS, 2002,41:3567-3575], be that two end surface of optical fiber connector at 1 meter long optical fiber polish, plate the high reflectance deielectric-coating and constitute the high-fineness fiber resonance cavity, observed the chamber ring-down time about 1 microsecond, and carried out bending loss of optical fiber and fast travelling waves of optical fibre sensing experiment, obtained initial success.But the shortcoming of this method is the technical sophistication of polishing and plating the high reflectance deielectric-coating on fiber end face, and cost height, and the limited bandwidth of high reflectance deielectric-coating generally about 10 nanometers, have limited the spectral measurement ranges that declines and swing in the chamber.Two of technology [Manish Gupta etc. formerly, OPTICSLETTERS, 2002,27:1878-1881], be to adopt two high reflectance Fiber Bragg Grating FBGs to constitute the high-fineness fiber resonance cavity, under the long situation in 10 meters chambeies, obtained the chamber ring-down time about 2 microseconds.The shortcoming of this method is must well mate as the wavelength of two fiber gratings of high reflective cavity mirror and bandwidth, and in addition, the spectral measurement ranges of this method is limited by the reflection bandwidth of fiber grating, generally about several nanometers.Simultaneously, above-mentioned technology formerly also has a common shortcoming: the efficient that incident light pulse is coupled into fiber resonance cavity depends on the reflectivity of input cavity mirror, reflectivity is high more, coupling efficiency is low more, and the light intensity that enters photodetector is weak more, and all there is detection limit in photodetector, know from formula 1 on the other hand, cavity mirrors reflectivity is high more, and the chamber ring-down time is just long more, and measurement sensitivity is just high more.That is to say the contradiction that has cavity mirrors reflectivity and input coupling efficiency, this has just limited optical fiber cavity and has declined and swing the further raising that sensing device is measured sensitivity.
Summary of the invention
In order to overcome the shortcoming and defect of above-mentioned technology formerly, the present invention proposes a kind of dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity that adopts fiber loop mirror to constitute, and this device should have cavity mirrors reflectivity height, resonator cavity fineness height, the zone of reflections is wide, spectral measurement ranges is wide, measurement is highly sensitive, advantage of simple structure.
Technical solution of the present invention:
A kind of dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity is characterized in being connected by light source and first driver, fiber resonance cavity, photodetector and signal acquiring processing system successively and constituting in it.
Described fiber resonance cavity is linked to each other with second fiber loop mirror by optical fiber by first fiber loop mirror and constitutes; Described first fiber loop mirror is connected and composed by the 3rd port of the first fiber coupler homonymy and the 4th port and first optical fiber loop; Described second fiber loop mirror is connected and composed by the 3rd port of the second fiber coupler homonymy and the 4th port and second optical fiber loop; The output terminal of described light source links to each other with first port of first fiber coupler, and second port of first fiber coupler links to each other with an end of described optical fiber; The other end of this optical fiber connects first port of second fiber coupler, and second port of this second fiber coupler links to each other with signal acquiring processing system through photodetector.
Described fiber resonance cavity, being linked to each other with first port of second fiber coupler by described optical fiber by second port of an annular mirror switch constitutes, and described second fiber loop mirror is connected and composed by the 3rd port of the second fiber coupler homonymy and the 4th port and second optical fiber loop; The output terminal of described light source links to each other with first port of this annular mirror switch; Second port of this annular mirror switch links to each other with an end of described optical fiber; This optical fiber other end connects first port of second fiber coupler, and second port of this second fiber coupler links to each other with signal acquiring processing system through photodetector.
The formation of described annular mirror switch is: the 3rd port of described the 3rd fiber coupler homonymy is connected with the two ends of the 4th port with the 3rd optical fiber loop, insert light-modulating cell in the 3rd optical fiber loop off-center position, this light-modulating cell is provided with first driving power, and this first driving power links to each other with described first driver and run-in synchronism.
The formation of described annular mirror switch is: the 3rd port of described the 3rd fiber coupler homonymy is connected with the two ends of the 4th port with the 3rd optical fiber loop, insert a semiconductor optical amplifier and the 3rd fiber coupler in the 3rd optical fiber loop off-center position, described semiconductor optical amplifier has second driving power, the 3rd port of described the 3rd fiber coupler connects a control laser instrument, this control laser instrument connects the 3rd driving power, and described the 3rd driving power is connected with described first driving power and synchronous working.
The formation of described annular mirror switch is: the 3rd port of described the 3rd fiber coupler homonymy is connected with the two ends of the 4th port with the 3rd optical fiber loop, one section highly nonlinear optical fiber and the 4th fiber coupler are inserted in the off-center position in the 3rd optical fiber loop, the 4th fiber coupler connects a ultrashort pulse laser, this ultrashort pulse laser is worked under the driving of pulse producer, and this pulse producer links to each other with first driver and synchronous working.
The formation of described annular mirror switch is: the 3rd port of described the 3rd fiber coupler homonymy is connected with the two ends of the 4th port with the 3rd optical fiber loop, a wavelength division multiplexer and one section Active Optical Fiber are inserted in the off-center position in the 3rd optical fiber loop, the 3rd end of described wavelength division multiplexer connects a pump laser, this pump laser is provided with second driver, and described second driver links to each other with first driver and synchronous working.
Characteristics of the present invention and advantage are as follows:
1, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention is compared with technology formerly, have cavity mirrors reflectivity height, advantage that the resonator cavity fineness is high, and reflection bandwidth is very wide, can reach tens nanometers, has the wide advantage of spectral measurement ranges;
2, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention, compare with technology formerly, cavity mirrors reflectivity can dynamic modulation, thereby under the condition that guarantees high-fineness, can obtain high luminous power coupling efficiency again, reduce the requirement of photodetector, can obtain higher measurement sensitivity;
3, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention is compared with technology formerly, and is simple in structure, makes easily, with low cost.
Description of drawings
Fig. 1 embodiment of the invention one: the optical fiber cavity of adopting fiber loop mirror to constitute the high-fineness fiber resonance cavity declines and swings the sensing device synoptic diagram;
Fig. 2 embodiment of the invention two: adopt high speed fibre annular mirror photoswitch to decline and swing the sensing device synoptic diagram as the optical fiber cavity of high-fineness fiber resonance cavity input cavity mirror;
Fig. 3 embodiment of the invention three: the optical fiber cavity that the nonlinear optical fiber that adopts semiconductor optical amplifier to constitute high reflection of annular mirror realization and height switch at a high speed through characteristic declines and swings the sensing device synoptic diagram;
Fig. 4 embodiment of the invention four: the nonlinear optical fiber annular mirror that adopts highly nonlinear optical fiber to constitute realizes that high reflection and the high characteristic that sees through switch optical fiber cavity at a high speed and decline and swing the sensing device synoptic diagram;
Fig. 5 embodiment of the invention five: the optical fiber cavity that the nonlinear optical fiber that adopts fiber amplifier to constitute high reflection of annular mirror realization and height switch at a high speed through characteristic declines and swings the sensing device synoptic diagram.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
Embodiment one
As shown in Figure 1, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity, it is connected by light source 1 and first driver 11, fiber resonance cavity, photodetector 5 and signal acquiring processing system 6 successively and constitutes.
Described fiber resonance cavity is linked to each other with second fiber loop mirror 3 by optical fiber 4 by first fiber loop mirror 2 and constitutes; Described first fiber loop mirror 2 is connected and composed by the 3rd port 213 of first fiber coupler, 21 homonymies and the 4th port 214 and first optical fiber loop 22; Described second fiber loop mirror 3 is connected and composed by the 3rd port 313 of second fiber coupler, 31 homonymies and the 4th port 314 and second optical fiber loop 32; The output terminal of described light source 1 links to each other with first port 211 of first fiber coupler 21, and second port 212 of first fiber coupler 21 links to each other with an end of optical fiber 4; These optical fiber 4 other ends connect first port 311 of second fiber coupler 31, and second port 312 of this second fiber coupler 31 links to each other with signal acquiring processing system 6 through photodetector 5.
Present embodiment is based on and adopts fiber loop mirror as fiber resonance cavity, and the optical fiber cavity that constitutes broadband high-fineness fiber resonance cavity declines and swings sensing device.The two- port 213 and 214 of the homonymy of 3dB first fiber coupler 21 is connected and composed first fiber loop mirror 2 with first optical fiber loops 22.The two- port 313 and 314 of the homonymy of 3dB second fiber coupler 31 is connected and composed second fiber loop mirror 3 with second optical fiber loops 32.Opposite side second port 212 of first fiber coupler 21 is connected to optical fiber 4.An other end of this optical fiber 4 is connected to second fiber coupler, 31 opposite sides, first port 311.The light wave that sends from light source 1 injects first port 211 of first fiber coupler 21, from the 3rd port 213 and the 4th port 214 beam splitting output, with clockwise with counterclockwise through first optical fiber loop 22, get back to first fiber coupler 21, and interfere therein; Again from first port 211 and 212 outputs of second port.Because the result who interferes, the light wave intensity of exporting from second port 212 is I
1=(1-2 η) I
0Exp (α l); And can be expressed as from the light wave intensity of first port 211 to the incident direction reflection: I
1B=4 η (1-η) I
0Exp (α l).I in the formula
0Be incident intensity; (1-η): η is the splitting ratio of fiber coupler; L is the length of optical fiber loop; α is the loss factor of optical fiber loop.Therefore, be the fiber loop mirror 2 of 1: 1 3dB first fiber coupler 21 formations with splitting ratio, ideal reflectivity can reach 100%.By adjusting the splitting ratio of first fiber coupler 21, can obtain the chamber and decline and swing desired reflectivity, such as reaching more than 99.9%.And therefore the fiber coupler commercialization with broadband character splitting ratio can obtain the fiber loop mirror that reflection bandwidth reaches tens nanometers.Second fiber loop mirror 3 has identical character.Like this, first fiber loop mirror 2, second fiber loop mirror 3 and optical fiber 4 constitute the high-fineness resonator cavity that a light pulse is vibrated therein back and forth.The light pulse that light source 1 sends enters first port 211 of first fiber coupler 21, because the high reflectance of first fiber loop mirror 2, the sub-fraction transmitted light is coupled into the broadband high-fineness fiber resonance cavity that is made of first fiber loop mirror 2, optical fiber 4 and second fiber loop mirror 3, comes back reflective and oscillatory extinction (promptly decline and swing) slowly in the chamber.In the chamber light pulse whenever back reflective once, photon transfers to outside the chamber and by photodetector 5 from second port 312 of second fiber coupler 31 by second fiber loop mirror 3 and surveys in the sub-fraction chamber.The output electric signal entering signal acquisition processing system 6 of photodetector 5.According to formula 1,, can realize high-acruracy survey to cavity loss by the chamber ring-down time constant that analysis to measure arrives.
Present embodiment has cavity mirrors reflectivity height, the wide advantage of spectral measurement ranges, and fiber loop mirror is to be made of the 3dB fiber coupler, and cost is very low.
Embodiment two
As shown in Figure 2, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention, described fiber resonance cavity is linked to each other with first port 311 of second fiber coupler 31 by optical fiber 4 by second port 712 of an annular mirror switch 7 and constitutes, and described second fiber loop mirror 3 is connected and composed with second optical fiber loops 32 by the 3rd port 313 and the 4th port 314 of second fiber coupler, 31 homonymies; The output terminal of described light source 1 links to each other with first port 711 of this annular mirror switch 7; Second port 712 of this annular mirror switch 7 links to each other with an end of described optical fiber 4; These optical fiber 4 other ends connect first port 311 of second fiber coupler 31, and second port 312 of this second fiber coupler 31 links to each other with signal acquiring processing system 6 through photodetector 5.The formation of described annular mirror switch 7 is: the 3rd port 713 of described the 3rd fiber coupler 71 homonymies is connected with the two ends of the 3rd optical fiber loop 72 with the 4th port 714, insert light-modulating cell 73 in the 3rd optical fiber loop 72 off-center positions, this light-modulating cell 73 is provided with first driving power 74, and this first driving power 74 links to each other with described first driver 11 and run-in synchronism.Light-modulating cell 73 is by first driving power, 74 drive controlling.
The fiber loop mirror 72 that has inserted modulating unit 73 is the fiber loop mirror switches that reflectivity is adjustable.Thereby constituting the fiber resonance cavity of the fiber resonance cavity of a high input coupling efficiency, broadband, high-fineness, declines and swings the detection sensing in realization high sensitivity and high-precision chamber.
In this structure, the 3rd port 713 of the 3rd fiber coupler 71 homonymies is connected by optical fiber loop 72 with the 4th port 714, constitute fiber loop mirror.In ring, insert light-modulating cell 73, form controllable optical fibre annular mirror 7.The operating characteristic of this controllable optical fibre annular mirror 7 is: when optical switch element 73 is in " all-pass " state, be input to the light signal of controllable optical fibre annular mirror 7 from first port 711 or second port 712, will distinguish former first port 711 of reflected back or second port 712.At this moment, controllable optical fibre annular mirror 7 is equivalent to a high reflection mirror, and it and optical fiber 4 and fiber loop mirror 3 constitute the fiber resonance cavity of a high-fineness.When light-modulating cell 73 is in " total reflection " state, from first port 711 be input to the light pulse of controllable optical fibre annular mirror 7 will be from the another port 712 outputs, injection fibre 4.This moment, the controllable optical fibre annular mirror 7 was equivalent to a coupling mechanism that transmitance is very high, it can with the light pulse power efficient be coupled into resonator cavity.In case light pulse injection fibre 4, the state of switches light switch element makes fiber resonance cavity return to the high-fineness state immediately.In this structure, the formation of second fiber loop mirror 3 and action principle are identical with second fiber loop mirror 3 among Fig. 1.Like this, controllable optical fibre annular mirror 7, optical fiber 4 and fiber loop mirror 3 have just constituted the fiber resonance cavity of a high input coupling efficiency, broadband, high-fineness.
The course of work of present embodiment is as follows: the light pulse that light source 1 sends enters first port 711 of the 3rd fiber coupler 71, and the light-modulating cell 73 of controllable optical fibre annular mirror light 7 synchronously switches to the high permeability state under the driving of first driving power 74.The duration of switching is enough short, and the light pulse in inputing to optical fiber 4 arrives before second port 712 of controllable optical fibre annular mirror 7 through second fiber loop mirror, 3 reflected back optical fiber 4, and controllable optical fibre annular mirror 7 has switched to high reflective condition.After this, light pulse just comes back reflective and oscillatory extinction (promptly decline and swing) slowly in the resonator cavity that is made of controllable optical fibre annular mirror 7, optical fiber 4 and second fiber loop mirror 3.In the chamber light pulse whenever back reflective once, photon transfers to outside the chamber by second port 312 of the fiber coupler 31 of second fiber loop mirror 3 in the sub-fraction chamber, and is surveyed by photodetector 5.The output electric signal entering signal acquisition processing system 6 of photodetector 5.According to formula 1,, can realize high-acruracy survey to cavity loss by the chamber ring-down time constant that analysis to measure arrives.
Present embodiment not only has the cavity mirrors reflectivity height, spectral measurement ranges is wide and advantage cheaply, and the modulation of the reflectivity by the input cavity mirror, has high coupling efficiency when making incident light pulse injection fibre resonator cavity, inject Effect of Back-Cavity Mirror and promptly recover high reflectivity, thereby solved high-fineness with the contradiction between the coupling efficiency, overcome the shortcoming of technology formerly, reduced the requirement of photodetector, improve the signal to noise ratio (S/N ratio) of measuring-signal, obtained higher measurement sensitivity.
The embodiment of the invention three
Fig. 3 is the embodiment of the invention three: the optical fiber cavity that the nonlinear optical fiber that adopts semiconductor optical amplifier to constitute high reflection of annular mirror realization and height switch at a high speed through characteristic declines and swings the sensing device synoptic diagram;
Among the figure: 74 is a semiconductor optical amplifier, and 741 is its second driving power.Semiconductor optical amplifier 74 not only has the effect of light amplification, and under the situation of different incident intensities, owing to optical non-linear effect changes effective refractive index.742 is a control laser instrument.The pulsed laser signal that it sends is annotated the 3rd through the 3rd fiber coupler 743 and is gone into optical fiber loop 72.744 are three driving power of control with laser instrument 742 pulses running, and its pulsed frequency and phase place and signal optical source 1 are synchronous and adjustable.
The principle of work of present embodiment is as follows: semiconductor optical amplifier 74 has corresponding gain under certain working current, compensate the loss of the 3rd optical fiber loop 72, make fiber loop mirror first port 711 and second port 712 play the effect of a high reflection mirror.When the control light pulse of sending from laser instrument 742 is injected into the 3rd optical fiber loop 72 by the 3rd fiber coupler 743, nonlinear interaction will take place in the test light pulse that control light pulse and light source 1 send on semiconductor optical amplifier 74.Therefore the mid point of the 3rd optical fiber loop 72 is departed from the installation site of this semiconductor optical amplifier 74, will be at the different semiconductor optical amplifiers 74 that arrive constantly from the test light pulse of the 3rd port 713 of the 3rd fiber coupler 71 and 714 outgoing of the 4th port.Regulate the pulse delay time of the 3rd driving power 744, the moment that the control light pulse that control laser instrument 742 is sent arrives semiconductor optical amplifier 74 only arrives semiconductor optical amplifier 74 synchronously and nonlinear interaction takes place with it with a light pulse in the test light pulse clockwise and transmission counterclockwise.The phase change of experience was just inequality when the 3rd optical fiber loop 72 was passed through in the test light pulse of clockwise like this and counterclockwise transmission.In the case, controllable optical fibre annular mirror 7 makes light pulse enter optical fiber 4 efficiently for the just effect of a high permeability of light pulse from light source 1 incident.Cut off the control light pulse then immediately, controllable optical fibre annular mirror 7 returns to the state of high reflectance, makes up the vibration chamber of a high-fineness.Because compole is short during the nonlinear response of semiconductor optical amplifier 74, roughly, therefore can realize switching at a high speed less than nanosecond order, satisfy high sensitivity, decline and swing measurement in high-precision chamber.
The embodiment of the invention four
Fig. 4 is the embodiment of the invention four: the nonlinear optical fiber annular mirror that adopts highly nonlinear optical fiber to constitute realizes that high reflection and the high characteristic that sees through switch optical fiber cavity at a high speed and decline and swing the sensing device synoptic diagram; 754 is one section highly nonlinear optical fiber among the figure, directly is connected with optical fiber loop 72.751 is that the ultrashort pulse laser of making usefulness is started to control in a generation, and it is worked under the driving of pulse producer 752.The pulse producer 752 and first driver 11 are synchronous, and have adjustable delay character.The laser that ultrashort pulse laser 751 sends injects highly nonlinear optical fiber 754 by the 4th fiber coupler 753.
The principle of work of this structure is as follows: highly nonlinear optical fiber has the optical non-linear effect more much higher than conventional fiber.When the test light pulse is sent through 71 beam splitting of the 3rd fiber coupler from LASER Light Source 1, respectively to pass through the 3rd optical fiber loop 72 clockwise and counterclockwise; Control laser pulse and test pulse send synchronously, and the control time-delay makes itself and clockwise light wave arrive highly nonlinear optical fiber section 754 simultaneously; And light wave had passed through this fiber segment before the control light wave arrives nonlinear optical fiber section 754 counterclockwise.Light wave is not subjected to the effect of highly nonlinear optical fiber 754 counterclockwise, and suitable pointer light wave has stood the cross-phase modulation effect of nonlinear effect, has obtained to have the phase change than big difference.Like this, when this two bundles light wave is got back to the 3rd fiber coupler 71, can all not reflect back owing to interference from incident port 711, but with higher transmittance injection fibre 4.By after the fiber loop mirror switch 7, control laser instrument 751 is in the phase in recurrent interval in this pulse.At this moment, highly nonlinear optical fiber section 754 is as broad as long for clockwise and counterclockwise light wave, produces identical phase shift.When they get back to the 3rd fiber coupler 71, will all play the effect of a high reflection mirror for light wave owing to interference to the reflection of incident port from its first port 711 and 712 incidents of second port.Thereby reaching high-level efficiency injects high Q value and declines and swing the purpose in chamber.
The embodiment of the invention five
Fig. 5 embodiment of the invention five: the optical fiber cavity that the nonlinear optical fiber that adopts fiber amplifier to constitute high reflection of annular mirror realization and height switch at a high speed through characteristic declines and swings the sensing device synoptic diagram.764 is one section rear-earth-doped Active Optical Fiber among the figure; It is connected with the 3rd optical fiber loop 72.761 for providing the pump laser of excitation energy to Active Optical Fiber.Pump laser is worked under second driver 762 promotes.Second driver 762 is synchronous with first driver 11 of testing light source, and has adjustable delay character.The pumping laser pulse is injected Active Optical Fiber 764 by wavelength division multiplexer 763, makes it have the effect of light amplification.
The principle of work of this structure is as follows: rear-earth-doped Active Optical Fiber 764 is under the effect of pumping laser, and absorptive pumping laser photon energy obtains the counter-rotating of population; It has amplification for concurrently injected flashlight.When the test light pulse is sent through 71 beam splitting of the 3rd fiber coupler from LASER Light Source 1, respectively to pass through the 3rd optical fiber loop 72 clockwise and counterclockwise; The pumping laser pulse is sent synchronously from pump laser 761 and test pulse, injects Active Optical Fiber 764 through wavelength division multiplexer 763; The control time-delay makes itself and clockwise light wave arrive Active Optical Fiber section 764 simultaneously, thereby makes clockwise light wave obtain to amplify.And light wave had passed through this fiber segment before the pump light pulse arrives Active Optical Fiber section 764 counterclockwise.Light wave is not subjected to the amplification of Active Optical Fiber 764 counterclockwise.Like this, when this two bundles light wave was got back to the 3rd fiber coupler 71, because two-beam wave intensity difference, the result of interference was that a part of light reflects back from incident port 711, and a part of in addition light wave enters optical fiber 4 to port 712 outputs.By after the fiber loop mirror switch 7, pump laser 761 is in the phase in recurrent interval in this pulse, but keeps the direct current output of a lower power levels, makes Active Optical Fiber 764 keep the state of not loss zero gain.Like this, it is as broad as long for clockwise and counterclockwise light wave, has not both had absorption, does not also have gain, and experiences identical phase shift.When they get back to the 3rd fiber coupler 71, will be owing to interference to the reflection of incident port, for from its first port 711 and and the light wave of second port, 712 incidents all play the effect of a high reflection mirror.Thereby reaching high-level efficiency injects high Q value and declines and swing the purpose in chamber.
Dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention can be realized the high-acruracy survey to cavity loss, can be used for carrying out the sensing measurement of different kinds of parameters, as long as tested parameter can cause the loss of fiber resonance cavity and change, perhaps the variation of tested parameter can be converted to the loss change of fiber resonance cavity by throw-over gear, for example concentration/refractive index of bending, strain, pressure, gas/liquid etc. can both be measured with dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity of the present invention.
Claims (7)
1, a kind of dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity is characterized in that it is connected by light source (1) and first driver (11), fiber resonance cavity, photodetector (5) and signal acquiring processing system (6) successively and constitutes.
2, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 1, it is characterized in that described fiber resonance cavity by first fiber loop mirror (2) by optical fiber (4) formation that links to each other with second fiber loop mirror (3); Described first fiber loop mirror (2) is connected and composed with first optical fiber loop (22) by the 3rd port (213) and the 4th port (214) of first fiber coupler (21) homonymy; Described second fiber loop mirror (3) is connected and composed with second optical fiber loop (32) by the 3rd port (313) and the 4th port (314) of second fiber coupler (31) homonymy; The output terminal of described light source (1) links to each other with first port (211) of first fiber coupler (21), and second port (212) of first fiber coupler (21) links to each other with an end of optical fiber (4); This optical fiber (4) other end connects first port (311) of second fiber coupler (31), and second port (312) of this second fiber coupler (31) links to each other with signal acquiring processing system (6) through photodetector (5).
3, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 1, it is characterized in that described fiber resonance cavity by second port (712) of an annular mirror switch (7) by optical fiber (4) formation that links to each other with first port (311) of second fiber coupler (31), described second fiber loop mirror (3) is connected and composed by the 3rd port (313) and same second optical fiber loop (32) of the 4th port (314) of second fiber coupler (31) homonymy; The output terminal of described light source (1) links to each other with first port (711) of this annular mirror switch (7); Second port (712) of this annular mirror switch (7) links to each other with an end of described optical fiber (4); This optical fiber (4) other end connects first port (311) of second fiber coupler (31), and second port (312) of this second fiber coupler (31) links to each other with signal acquiring processing system (6) through photodetector (5).
4, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 3, the formation that it is characterized in that described annular mirror switch (7) is: the 3rd port (713) of described the 3rd fiber coupler (71) homonymy is connected with the two ends of the 4th port (714) with the 3rd optical fiber loop (72), insert light-modulating cell (73) in the 3rd optical fiber loop (72) off-center position, this light-modulating cell (73) is provided with first driving power (74), and this first driving power (74) links to each other with described first driver (11) and run-in synchronism.
5, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 3, the formation that it is characterized in that described annular mirror switch (7) is: the 3rd port (713) of described the 3rd fiber coupler (71) homonymy is connected with the two ends of the 4th port (714) with the 3rd optical fiber loop (72), insert a semiconductor optical amplifier (74) and the 4th fiber coupler (743) in the 3rd optical fiber loop (72) off-center position, described semiconductor optical amplifier (74) has second driving power (741), the 3rd port of described the 3rd fiber coupler (743) connects a control laser instrument (742), this control laser instrument (742) connects the 3rd driving power (744), and described the 3rd driving power (744) is connected with described first driver (11) and synchronous working.
6, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 3, the formation that it is characterized in that described annular mirror switch (7) is: the 3rd port (713) of described the 3rd fiber coupler (71) homonymy is connected with the two ends of the 4th port (714) with the 3rd optical fiber loop (72), one section highly nonlinear optical fiber (754) and the 4th fiber coupler (753) are inserted in the off-center position in the 3rd optical fiber loop (72), the 4th fiber coupler (753) connects a ultrashort pulse laser (751), this ultrashort pulse laser (751) is worked under the driving of pulse generation (752), and this pulse producer (752) links to each other with first driver (11) and synchronous working.
7, dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity according to claim 3, the formation that it is characterized in that described annular mirror switch (7) is: the 3rd port (713) of described the 3rd fiber coupler (71) homonymy is connected with the two ends of the 4th port (714) with the 3rd optical fiber loop (72), a wavelength division multiplexer (763) and one section Active Optical Fiber (764) are inserted in the off-center position in the 3rd optical fiber loop (72), the 3rd end of described wavelength division multiplexer (763) connects a pump laser (761), this pump laser (761) is provided with second driver (762), and described second driver (762) links to each other with first driver (11) and synchronous working.
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| CN101871791A (en) * | 2010-06-30 | 2010-10-27 | 中国人民解放军国防科学技术大学 | Multi-parameter sensor and measurement system based on photonic crystal fiber |
| CN101776518B (en) * | 2010-01-12 | 2012-02-22 | 浙江师范大学 | Method and device for detecting spectral characteristics of optical device |
| CN102607702A (en) * | 2012-03-21 | 2012-07-25 | 昆山煜肸传感器科技有限公司 | Optical-frequency-domain vernier-method spectrometer with broadband reference light source |
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| CN101776518B (en) * | 2010-01-12 | 2012-02-22 | 浙江师范大学 | Method and device for detecting spectral characteristics of optical device |
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| CN101871791B (en) * | 2010-06-30 | 2012-03-14 | 中国人民解放军国防科学技术大学 | Multi-parameter sensor and measurement system based on photonic crystal fiber |
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| CN112969909A (en) * | 2018-11-09 | 2021-06-15 | 慕尼黑科技大学 | Multicolor optical resonator for imaging methods |
| CN111103260A (en) * | 2020-01-21 | 2020-05-05 | 江苏师范大学 | System and method for detecting intermediate infrared all-fiber cavity ring-down trace gas |
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