CN1664517A - All-fiber cavity ring-down absorption spectrum detection sensing device - Google Patents

Abstract

Translated fromChinese

一种全光纤腔衰荡吸收光谱检测传感装置，其结构是它依次由光源及其第一驱动器、光纤谐振腔、光电探测器和信号采集处理系统连接而构成。该装置具有腔镜反射率高、谐振腔精细度高、反射带宽宽、光谱测量范围宽、光功率耦合效率高、测量灵敏度高和结构简单的优点。

An all-fiber cavity ring-down absorption spectrum detection sensor device is structured to be sequentially connected by a light source and its first driver, a fiber resonant cavity, a photodetector and a signal acquisition and processing system. The device has the advantages of high cavity mirror reflectivity, high resonant cavity fineness, wide reflection bandwidth, wide spectrum measurement range, high optical power coupling efficiency, high measurement sensitivity and simple structure.

Description

Dying oscillation absorption spectrum detecting and sensing device for all optical fiber cavity

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,

$\mathrm{\τ}=\frac{{\mathrm{Ln}}_{\mathrm{eff}}}{c[(1-R)+l]}----\left(1\right)$

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, asformula 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 andfirst driver 11, fiber resonance cavity,photodetector 5 and signalacquiring processing system 6 successively and constitutes.

Described fiber resonance cavity is linked to each other with secondfiber loop mirror 3 byoptical fiber 4 by firstfiber loop mirror 2 and constitutes; Described firstfiber loop mirror 2 is connected and composed by the3rd port 213 of first fiber coupler, 21 homonymies and the4th port 214 and firstoptical fiber loop 22; Described secondfiber loop mirror 3 is connected and composed by the3rd port 313 of second fiber coupler, 31 homonymies and the4th port 314 and secondoptical fiber loop 32; The output terminal of described light source 1 links to each other withfirst port 211 offirst fiber coupler 21, andsecond port 212 offirst fiber coupler 21 links to each other with an end ofoptical fiber 4; Theseoptical fiber 4 other ends connectfirst port 311 ofsecond fiber coupler 31, andsecond port 312 of thissecond fiber coupler 31 links to each other with signal acquiringprocessing system 6 throughphotodetector 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 3dBfirst fiber coupler 21 is connected and composed firstfiber loop mirror 2 with first optical fiber loops 22.The two-port 313 and 314 of the homonymy of 3dBsecond fiber coupler 31 is connected and composed secondfiber loop mirror 3 with second optical fiber loops 32.Opposite sidesecond port 212 offirst fiber coupler 21 is connected to optical fiber 4.An other end of thisoptical fiber 4 is connected to second fiber coupler, 31 opposite sides, first port 311.The light wave that sends from light source 1 injectsfirst port 211 offirst fiber coupler 21, from the3rd port 213 and the4th port 214 beam splitting output, with clockwise with counterclockwise through firstoptical fiber loop 22, get back tofirst fiber coupler 21, and interfere therein; Again fromfirst port 211 and 212 outputs of second port.Because the result who interferes, the light wave intensity of exporting fromsecond port 212 is I₁=(1-2 η) I₀Exp (α l); And can be expressed as from the light wave intensity offirst port 211 to the incident direction reflection: I_1B=4 η (1-η) I₀Exp (α l).I in the formula₀Be 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 thefiber loop mirror 2 of 1: 1 3dBfirst fiber coupler 21 formations with splitting ratio, ideal reflectivity can reach 100%.By adjusting the splitting ratio offirst 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.Secondfiber loop mirror 3 has identical character.Like this, firstfiber loop mirror 2, secondfiber loop mirror 3 andoptical 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 entersfirst port 211 offirst fiber coupler 21, because the high reflectance of firstfiber loop mirror 2, the sub-fraction transmitted light is coupled into the broadband high-fineness fiber resonance cavity that is made of firstfiber loop mirror 2,optical fiber 4 and secondfiber 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 byphotodetector 5 fromsecond port 312 ofsecond fiber coupler 31 by secondfiber loop mirror 3 and surveys in the sub-fraction chamber.The output electric signal entering signalacquisition 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 withfirst port 311 ofsecond fiber coupler 31 byoptical fiber 4 bysecond port 712 of anannular mirror switch 7 and constitutes, and described secondfiber loop mirror 3 is connected and composed with secondoptical fiber loops 32 by the3rd port 313 and the4th port 314 of second fiber coupler, 31 homonymies; The output terminal of described light source 1 links to each other withfirst port 711 of thisannular mirror switch 7;Second port 712 of thisannular mirror switch 7 links to each other with an end of describedoptical fiber 4; Theseoptical fiber 4 other ends connectfirst port 311 ofsecond fiber coupler 31, andsecond port 312 of thissecond fiber coupler 31 links to each other with signal acquiringprocessing system 6 through photodetector 5.The formation of describedannular mirror switch 7 is: the3rd port 713 of described the3rd fiber coupler 71 homonymies is connected with the two ends of the 3rdoptical fiber loop 72 with the 4th port 714, insert light-modulating cell 73 in the 3rdoptical 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 describedfirst driver 11 and run-in synchronism.Light-modulating cell 73 is by first driving power, 74 drive controlling.

Thefiber 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, the3rd port 713 of the3rd fiber coupler 71 homonymies is connected byoptical 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 fibreannular mirror 7 is: when optical switch element 73 is in " all-pass " state, be input to the light signal of controllable optical fibreannular mirror 7 fromfirst port 711 orsecond port 712, will distinguish formerfirst port 711 of reflected back or second port 712.At this moment, controllable optical fibreannular mirror 7 is equivalent to a high reflection mirror, and it andoptical fiber 4 andfiber loop mirror 3 constitute the fiber resonance cavity of a high-fineness.When light-modulating cell 73 is in " total reflection " state, fromfirst port 711 be input to the light pulse of controllable optical fibreannular mirror 7 will be from theanother port 712 outputs, injection fibre 4.This moment, the controllable optical fibreannular 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 lightpulse 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 secondfiber loop mirror 3 and action principle are identical with secondfiber loop mirror 3 among Fig. 1.Like this, controllable optical fibreannular mirror 7,optical fiber 4 andfiber 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 entersfirst port 711 of the3rd fiber coupler 71, and the light-modulating cell 73 of controllable optical fibreannular 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 tooptical fiber 4 arrives beforesecond port 712 of controllable optical fibreannular mirror 7 through second fiber loop mirror, 3 reflected backoptical fiber 4, and controllable optical fibreannular 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 fibreannular 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 bysecond port 312 of thefiber coupler 31 of secondfiber loop mirror 3 in the sub-fraction chamber, and is surveyed by photodetector 5.The output electric signal entering signalacquisition 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 3rdoptical fiber loop 72, make fiber loop mirrorfirst port 711 andsecond 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 3rdoptical 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 3rdoptical 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 the3rd port 713 of the3rd 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 3rdoptical fiber loop 72 was passed through in the test light pulse of clockwise like this and counterclockwise transmission.In the case, controllable optical fibreannular mirror 7 makes light pulse enteroptical 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 fibreannular 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.Thepulse producer 752 andfirst driver 11 are synchronous, and have adjustable delay character.The laser thatultrashort pulse laser 751 sends injects highly nonlinearoptical fiber 754 by the4th 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 3rdoptical 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 nonlinearoptical fiber section 754 simultaneously; And light wave had passed through this fiber segment before the control light wave arrives nonlinearoptical fiber section 754 counterclockwise.Light wave is not subjected to the effect of highly nonlinearoptical 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 the3rd fiber coupler 71, can all not reflect back owing to interference fromincident port 711, but with higher transmittance injection fibre 4.By after the fiberloop mirror switch 7,control laser instrument 751 is in the phase in recurrent interval in this pulse.At this moment, highly nonlinearoptical fiber section 754 is as broad as long for clockwise and counterclockwise light wave, produces identical phase shift.When they get back to the3rd 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 itsfirst 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 withfirst 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 3rdoptical 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 the3rd fiber coupler 71, because two-beam wave intensity difference, the result of interference was that a part of light reflects back fromincident port 711, and a part of in addition light wave entersoptical fiber 4 toport 712 outputs.By after the fiberloop 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 the3rd fiber coupler 71, will be owing to interference to the reflection of incident port, for from itsfirst 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)

Translated fromChinese

1、一种全光纤腔衰荡吸收光谱检测传感装置，其特征在于它依次由光源(1)及其第一驱动器(11)、光纤谐振腔、光电探测器(5)和信号采集处理系统(6)连接而构成。1. An all-fiber cavity ring-down absorption spectrum detection sensing device is characterized in that it consists of a light source (1) and its first driver (11), an optical fiber resonant cavity, a photodetector (5) and a signal acquisition and processing system in sequence (6) connected to form.2、根据权利要求1所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的光纤谐振腔由第一光纤环形镜(2)通过光纤(4)与第二光纤环形镜(3)相连构成；所述的第一光纤环形镜(2)由第一光纤耦合器(21)同侧的第三端口(213)和第四端口(214)同第一光纤环路(22)连接构成；所述的第二光纤环形镜(3)由第二光纤耦合器(31)同侧的第三端口(313)和第四端口(314)同第二光纤环路(32)连接构成；所述的光源(1)的输出端与第一光纤耦合器(21)的第一端口(211)相连，第一光纤耦合器(21)的第二端口(212)与光纤(4)的一端相连；该光纤(4)另一端连接第二光纤耦合器(31)的第一端口(311)，该第二光纤耦合器(31)的第二端口(312)经光电探测器(5)和信号采集处理系统(6)相连。2. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 1, characterized in that the optical fiber resonator consists of the first fiber optic loop mirror (2) through the optical fiber (4) and the second fiber optic loop mirror (3) connect to form; Described first optical fiber loop mirror (2) is connected with the first optical fiber loop (22) by the third port (213) and the fourth port (214) of the same side of the first fiber coupler (21) ) connected to form; the second optical fiber loop mirror (3) is connected with the second optical fiber loop (32) by the third port (313) and the fourth port (314) of the same side of the second fiber coupler (31) Composition; the output end of the light source (1) is connected to the first port (211) of the first fiber coupler (21), and the second port (212) of the first fiber coupler (21) is connected to the optical fiber (4) The other end of the optical fiber (4) is connected to the first port (311) of the second fiber coupler (31), and the second port (312) of the second fiber coupler (31) passes through the photodetector (5 ) is connected to the signal acquisition and processing system (6).3、根据权利要求1所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的光纤谐振腔由一环形镜开关(7)的第二端口(712)通过光纤(4)与第二光纤耦合器(31)的第一端口(311)相连构成，所述的第二光纤环形镜(3)由第二光纤耦合器(31)同侧的第三端口(313)和第四端口(314)同第二光纤环路(32)连接构成；所述的光源(1)的输出端与该环形镜开关(7)的第一端口(711)相连；该环形镜开关(7)的第二端口(712)与所述的光纤(4)的一端相连；该光纤(4)另一端连接第二光纤耦合器(31)的第一端口(311)，该第二光纤耦合器(31)的第二端口(312)经光电探测器(5)和信号采集处理系统(6)相连。3. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 1, characterized in that the optical fiber resonator is connected by the second port (712) of a ring mirror switch (7) through the optical fiber (4) It is connected with the first port (311) of the second optical fiber coupler (31), and the second optical fiber loop mirror (3) is composed of the third port (313) on the same side of the second optical fiber coupler (31) and the second Four ports (314) are connected with the second optical fiber loop (32) to form; the output end of the light source (1) is connected to the first port (711) of the ring mirror switch (7); the ring mirror switch (7) ) of the second port (712) is connected to one end of the optical fiber (4); the other end of the optical fiber (4) is connected to the first port (311) of the second fiber coupler (31), and the second fiber coupler The second port (312) of (31) is connected to the signal acquisition and processing system (6) via the photodetector (5).4、根据权利要求3所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的环形镜开关(7)的构成是：所述的第三光纤耦合器(71)同侧的第三端口(713)和第四端口(714)与第三光纤环路(72)的两端连接，在第三光纤环路(72)偏离中心位置接入光调制单元(73)，该光调制单元(73)设有第一驱动电源(74)，该第一驱动电源(74)与所述的第一驱动器(11)相连并同步运转。4. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 3, characterized in that the structure of the ring mirror switch (7) is: the same side of the third fiber coupler (71) The third port (713) and the fourth port (714) of the third optical fiber loop (72) are connected to both ends of the third optical fiber loop (72), and the optical modulation unit (73) is connected to the off-center position of the third optical fiber loop (72), the The light modulation unit (73) is provided with a first driving power supply (74), and the first driving power supply (74) is connected with the first driver (11) and operates synchronously.5、根据权利要求3所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的环形镜开关(7)的构成是：所述的第三光纤耦合器(71)同侧的第三端口(713)和第四端口(714)与第三光纤环路(72)的两端连接，在第三光纤环路(72)偏离中心位置接入一个半导体光放大器(74)和第四光纤耦合器(743)，所述的半导体光放大器(74)具有第二驱动电源(741)，所述的第三光纤耦合器(743)的第三端口连接一控制激光器(742)，该控制激光器(742)连接第三驱动电源(744)，所述的第三驱动电源(744)与所述的第一驱动器(11)连接并同步工作。5. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 3, characterized in that the structure of the ring mirror switch (7) is: the same side of the third fiber coupler (71) The third port (713) and the fourth port (714) are connected to the two ends of the third optical fiber loop (72), and a semiconductor optical amplifier (74) and The fourth fiber coupler (743), the semiconductor optical amplifier (74) has a second drive power supply (741), the third port of the third fiber coupler (743) is connected to a control laser (742), The control laser (742) is connected to a third driving power supply (744), and the third driving power supply (744) is connected to the first driver (11) and works synchronously.6、根据权利要求3所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的环形镜开关(7)的构成是：所述的第三光纤耦合器(71)同侧的第三端口(713)和第四端口(714)与第三光纤环路(72)的两端连接，在第三光纤环路(72)中偏离中心位置接入一段高非线性光纤(754)和第四光纤耦合器(753)，该第四光纤耦合器(753)连接一超短脉冲激光器(751)，该超短脉冲激光器(751)在脉冲发生(752)的驱动下工作，该脉冲发生器(752)与第一驱动器(11)相连并同步工作。6. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 3, characterized in that the structure of the ring mirror switch (7) is: the same side of the third fiber coupler (71) The third port (713) and the fourth port (714) of the third optical fiber loop (72) are connected to both ends of the third optical fiber loop (72), and a section of high nonlinear optical fiber (754) is inserted in the third optical fiber loop (72) from the center position ) and the fourth fiber coupler (753), the fourth fiber coupler (753) is connected to an ultrashort pulse laser (751), and the ultrashort pulse laser (751) works under the drive of pulse generation (752), the The pulse generator (752) is connected with the first driver (11) and works synchronously.7、根据权利要求3所述的全光纤腔衰荡吸收光谱检测传感装置，其特征在于所述的环形镜开关(7)的构成是：所述的第三光纤耦合器(71)同侧的第三端口(713)和第四端口(714)与第三光纤环路(72)的两端连接，在第三光纤环路(72)中偏离中心位置接入一波分复用器(763)和一段有源光纤(764)，所述的波分复用器(763)的第三端连接一泵浦激光器(761)，该泵浦激光器(761)设有第二驱动器(762)，所述的第二驱动器(762)与第一驱动器(11)相连并同步工作。7. The all-fiber cavity ring-down absorption spectrum detection sensor device according to claim 3, characterized in that the structure of the ring mirror switch (7) is: the same side of the third fiber coupler (71) The third port (713) and the fourth port (714) are connected to the two ends of the third optical fiber loop (72), and in the third optical fiber loop (72), a wavelength division multiplexer ( 763) and a section of active optical fiber (764), the third end of the wavelength division multiplexer (763) is connected to a pump laser (761), and the pump laser (761) is provided with a second driver (762) , the second driver (762) is connected with the first driver (11) and works synchronously.

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