CN101871879B - Trace gas detection method based on micro resonance loop array spectrum-dividing technology and detector - Google Patents
Trace gas detection method based on micro resonance loop array spectrum-dividing technology and detector Download PDFInfo
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Abstract
The invention provides a trace gas detection method based on a micro resonance loop array spectrum-dividing technology and a detector. In the method, infrared laser firstly passes through a gas chamber, and then enters a micro resonance loop array consisting of a plurality of circular or racetrack micro resonance loops for coupling and spectrum-dividing; resonant wavelength light in the infrared laser after passing through the gas chamber is coupled and output by download waveguides of corresponding micro resonance loops; the light intensity of the coupled and output light is detected by photodetectors; and the components and the concentration of a gas to be tested are detected according to the change of the light intensity. The detector has a structure that a light source is connected with the gas chamber through a light path or optical fiber, the light output end of the gas chamber is connected with upload waveguides through an optical fiber and waveguide coupling device, the plurality of photodetectors are respectively connected with the plurality of download waveguides, and the micro resonance loop array is arranged between the upload waveguides and the download waveguides. The invention has skilled design, can be used for simultaneously detecting a plurality of gases with high detection accuracy, and can realize the integration and the portability of the detector.
Description
Technical field
The invention belongs to the minimum gas detection range, relate to a kind of trace gas detection method and detector based on micro resonance loop array spectrum-dividing technology.
Technical background
Gas-detecting device is the equipment that can discern gas componant and measure gas concentration quantitatively, and at air quality surveillance, industrial gaseous waste and automotive emission detect, and the fields such as prevention that toxic and harmful is revealed are widely used.The trace toxic harmful gas is in petrochemical complex, metallurgy, and coal, glass, cement, microelectronics, industrial circles such as the incineration of garbage produce in a large number, thereby need monitoring in real time and handled.According to estimates, only detect and environmental pollution detects this two fields at industrial gaseous waste, every year required gas-detecting device up to 1,700,000, about 6,800,000,000 yuan of the output value.The detected gas object generally comprises multiple minimum gas, as sulfide, and nitride, hydrogen fluoride, carbon monoxide, carbon dioxide, oxygen, water vapor etc. need the quick concentration that also detects all gases composition in high sensitivity.Existing gas detection technology mainly contains wet chemistry method, chromatogram or mass spectroscopy, and micro electronmechanical sensing technology, fuel cell technology, the electrochemical sensing technology, and optical technology etc.Wet chemistry method
[1]Utilize the variation of amount behind gas and the liquid generation chemical reaction to calculate the concentration of gas, it is low to have sensitivity, the shortcoming that measuring speed is slow.Chromatography
[2]Normal adopt thermal conductivity cell detector or hydrogen flame detector, though these two kinds of detector technologies comparative maturity all exists the surveying instrument volume big, the cost height, sensitivity is low, the shortcoming that the reaction time is long.Mass spectroscopy
[3]Similar shortcoming is also arranged.Micro electronmechanical sensing technology
[4]Though have characteristics such as short and volume of reaction time is little, its sensitivity is also lower, can only reach PPM (Parts Per Million, 1,000,000/) rank.Fuel cell technology
[5]Then because battery has cumulative effect, so service time is long more, error is big more.The electrochemical sensing technology
[6]Be the employed main method of present most of detector, but its sensitivity still is not enough to detect the minimum gas of PPB (Parts Per Billion, part per billion) magnitude such as hydrogen fluoride etc.Optical means has highly sensitive, and speed is fast, and selectivity is good, and can measure the advantage of multiple gases simultaneously.Optical means has become the main developing direction of gas detection technology from now on.Present gas detection technology based on optical means has multiple, as NDIR (Non-Dispersive Infrared) technology (Non-dispersive infrared)
[7]But this kind method need be compared two spectral region: gas absorption district and uptake zone not, thereby only be applicable to and measure wide band absorption gas; Fourier-transform infrared technology (FTIR)
[8]Measuring accuracy can only reach the PPM level at present, and some toxic gas such as hydrofluoric concentration just can do a lot of damage to environment above several PPM, and make the people feel to suffocate, even dead, promptly to be lower than the toxic and harmful of PPM level most important so detect super low concentration; Tunable diode lasers absorption spectrum technology (Tunable Diode Laser Absorption Spectroscopy, TDLAS)
[9]Utilize tunable diode lasers and photo-detector, the measurement in conjunction with the realization higher sensitivity of spectrometer, but this kind method once can only be measured a kind of gas.Optoacoustic spectroscopy (Photoacoustic spectroscopy)
[10]Detection sensitivity can reach the PPB level, but this kind method is subjected to the influence of ground unrest easily.When containing the sample measurement of multiple gases composition, it is particularly important that light splitting technology seems.Past people adopts spectroscope to add a series of loaded down with trivial details discrete geometrical optics components and parts to carry out beam split mostly, and it is very unstable to cause system to move like this, carries and install also very inconvenient.
List of references:
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2.J.Duinker, D.Schulz, and G.Petrick, " the multidimensional gas chromatogram technology of utilizing electron capture to survey is used for measuring the Toxic of polychlorinated biphenyl potpourri; " analytical chemistry 60,478-482 (1988) .[J.Duinker, D.Schulz, and G.Petrick, " Multidimensional gas chromatography with electron capture detection for thedetermination of toxic congeners in polychlorinated biphenyl mixtures; " Analytical Chemistry 60,478-482 (1988) .]
3.J.Gouw, C.Warneke, T.Karl, G.Eerdekens, C.Veen, and R.Fall, " measuring the sensitivity and the specific aim of the proton-transmission-reaction substance spectrometry of minimum gas in the atmosphere; " international mass spectrum magazine 223,365-382 (2003) .[J.Gouw, C.Warneke, T.Karl, G.Eerdekens, C.Veen, and R.Fall, " Sensitivity and specificity of atmospherictrace gas detection by proton-transfer-reaction mass spectrometry; " International J.Mass.Spectrometry 223,365-382 (2003) .]
4.D.Meier, C.Taylor, R.Cavicchi, M.Ellzy, K.Sumpter, and S.Semancik, " utilizing the microsensor array detection chemical weapons composition of micro-electromechanical technology compatibility; " international electronic apparatus engineering periodical: sensor magazine 5,712-725 (2005) .[D.Meier, C.Taylor, R.Cavicchi, M.Ellzy, K.Sumpter, and S.Semancik, " Chemicalwarfare agent detection using MEMS-compatible microsensor arrays; " IEEE J.Sensors 5,712-725 (2005) .]
5.W.Liu, and D.Zucherbrod, " detecting the hydrogen peroxide in the PEM fuel cell when participating in the cintest; " ECS's proceedings 152, A1165-A1170 (2005) .[W.Liu, and D.Zucherbrod, " In situ detection of hydrogen peroxidein PEM fuel cells; " J.Electrochem.Soc.152, A1165-A1170 (2005) .]
6.W.Weppner, " solid-state electrochemistry gas sensor, " sensor and controller 12,107-119 (1987) .[W.Weppner, " Solid-state electrochemical gas sensors, " Sensors and Actuators 12,107-119 (1987) .]
7.R.Rubio, J.Santander, L.Fonseca, N.Sabate, I.Gracia, C.Cane, S.Udina, and S.Marco, " non-selective NDIR (Non-Dispersive Infrared) array is used for detection of gas, " sensor and controller B: chemistry 127,69-73 (2007) .[R.Rubio, J.Santander, L.Fonseca, N.Sabate, I.Gracia, C.Cane, S.Udina, and S.Marco, " Non-selective NDIR array for gas detection; " Sensors and Actuators B:Chemical 127,69-73 (2007) .]
8.D.Griffith, " the synthetic verification and the quantitative analysis of gas phase FFIR; " application of spectral 50,59-70 (1996) .[D.Griffith, " Synthetic calibration and quantitative analysis of gas-phase FT-IR spectra; " Applied Spectroscopy 50,59-70 (1996) .]
9.I.Linnerud, P.Kaspersen, and T.Jaeger, " utilizing the gas in the diode laser spectrum monitoring processing industry, " applied physics B: laser instrument and optics 67,297-305 (1998) .[I.Linnerud, P.Kaspersen, and T.Jaeger, " Gasmonitoring in the process industry using diode laser spectroscopy; " Applied Physics B:Lasers andOptics 67,297-305 (1998) .]
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Summary of the invention
The objective of the invention is to propose a kind of trace gas detection method and detector based on micro resonance loop array spectrum-dividing technology.
Technical solution of the present invention is as follows:
A kind of trace gas detection method based on micro resonance loop array spectrum-dividing technology, concrete steps are:
With wide spectrum light source or continuously the infrared laser that sends of tunable laser by a gas compartment that is used to charge into gas to be measured, gas compartment is provided with the micro-resonance loop array of being made up of the micro-resonance loop of a plurality of annulars or runway shape outward, because above-mentioned different micro-resonance loop has different resonant wavelengths because of having different girths or refractive index, therefore, can be by the resonant wavelength light in the infrared laser behind the gas compartment by the output of the download waveguide-coupled of corresponding micro-resonance loop, detect the light intensity of coupling output light again by photo-detector, the corresponding photo-detector of the download waveguide of each micro-resonance loop; Again by formula
Calculate the air pressure P of a certain gas to be measured, I is for being detected the light intensity after the light wave that obtains passes through gas, I in the formula by photo-detector
0Pass through gas light intensity before for detect the light wave that obtains by photo-detector, L is infrared laser passes gas to be measured in gas compartment a length, α is the absorption coefficient of this kind gas to be measured, α is a known constant, finally obtains gas concentration to be measured according to the air pressure P of gas to be measured and the corresponding relation of gas concentration to be measured at last.
Here the wide spectrum light source of saying is meant the characteristic wavelength that generally comprises several gases, and spectral range is that tens nanometers to hundreds of nanometer does not wait;
As everyone knows, the pass of gas pressure intensity and concentration is:
Wherein n is a gas molecule number in the unit volume, is converted into concentration (for known technology) again by n, and k is a Boltzmann constant, and T is the kelvin degree of gaseous environment, and ρ is a gas density, and M is the gas molal weight.Because the temperature and the gas volume of a container of gas can accurately be measured with conventional method, therefore just can obtain gas volume concentration (with PPM, RRB etc. are unit) or mass concentration (representing) with the contained gaseous mass of unit volume gas according to following formula.
Described micro-resonance loop array is made up of the micro-resonance loop of 2-20 different girths.
A kind of minimum gas detector based on micro resonance loop array spectrum-dividing technology, the light source that is used to send infrared laser joins by the light input end of light path or optical fiber and gas compartment, gas compartment is provided with and extracts or the gas injection body device, the light output end of gas compartment by optical fiber-Waveguide coupling arrangement with upload waveguide and join, a plurality of photo-detectors are connected respectively with a plurality of download waveguides, are provided with the micro-resonance loop array of being made up of a plurality of micro-resonance loops uploading waveguide and download between the waveguide.
Described micro-resonance loop is annular or runway shape, and a plurality of micro-resonance loops are delegation and are arranged in order.
Light source adopts infrared laser, output power is 2-150mW, the wavelength of infrared laser is 700nm～3000nm, the effective refractive index of micro-resonance loop waveguide is 2.3836, the distance of uploading waveguide and micro-resonance loop and downloading between waveguide and the micro-resonance loop is the coupling interval, and photo-detector adopts mixes the germanium photo-detector.
Technical conceive of the present invention is:
The present invention is mainly changing the concentration of measuring gas by the light wave of measuring the multiple gases characteristic absorption spectrum by the light intensity before and after the gas.We know that in gas molecule, the vibration of atom can excite or absorb certain photon energy, and this photon energy is not enough to the electronics in the excited atom.The energy that atomic vibration had absorb with it or the energy of excitation photon corresponding, the pairing spectrum of the photon of these a series of different-energies that excite or absorb is the absorption or the emission spectrum of this gas, is referred to as characteristic spectrum.The characteristic spectrum of gas is generally at region of ultra-red, and wherein near infrared region refers to the zone of wavelength coverage at 800nm-5000nm, and the characteristic spectrum of most of gas is positioned near infrared region.The object of studying among the present invention is a gas, and the characteristic absorption spectrum of detected gas will be the content of selective analysis.Because the absorption line difference of every kind of gas even if there is multiple gases to mix, also can identify every kind of gas according to the absorption spectra feature.The characteristic absorption spectrum of gas can utilize the theoretical formula of spectrum calculating or the method for measuring to obtain, and the scientific research personnel has obtained the absorption spectrum of most of common gas.
When the light wave that meets the gas absorption spectra characteristic frequency passed through gas to be detected, because the selectivity of gas absorbs, the light intensity of light wave can be decayed in the absorption spectrum district.According to Bo Ge-Lambert (Bouguer-Lambert) rule, the light intensity of the light that photo-detector detects after by gas is:
I＝I
0e
-αLP (1)
Wherein, I is for surveying light by the light intensity behind the gas, I
0For light wave passes through gas light intensity before, α is the absorption coefficient of this gas, and L is the gas length that light wave passes through, and P is the air pressure of this gas.Because the absorption coefficient of gas is a constant and can measures in advance, the length L of gas can directly be measured, therefore measured light wave by the light intensity value before and after this gas, just can utilize formula (1) to calculate the air pressure of gas, thereby know the concentration of this gas.The absorption spectrum measuring technique has measurement result precision height, and measuring speed is fast, and is highly sensitive, good reliability, simple advantage is safeguarded in no spillage of material, and, do not exist between the light wave to interfere with each other, be not subjected to the influence of periphery electromagnetic environment, very low to the requirement of amblent air temperature.
From (1) formula analysis as can be known, the measuring accuracy of gas concentration is by the sensitivity of photo-detector, the length of gas light path and the size decision of this absorption coefficient.For the precision that the raising system detects, can improve the light intensity detection accuracy of photo-detector and prolong the detection of gas distance.For example, for the low especially gas of concentration, can adopt the method that prolongs gas light path to strengthen absorbing.Measuring accuracy by existing photodetection instrument is a nanowatt, and the detection of gas distance is the rice order of magnitude, and the measuring accuracy that can estimate this kind method can reach PPB.
Beneficial effect:
The invention discloses a kind of trace gas detection method and detector based on micro resonance loop array spectrum-dividing technology, at first, the infrared laser that wide spectrum light source or continuous tunable laser send is by a miniature chamber, this miniature chamber can or be full of minimum gas by vacuum pumping, and wherein minimum gas is as object to be detected.Then, be coupled into the micro-resonance loop array of forming by a plurality of waveguide circular ring types or racetrack micro-resonance loop by the infrared laser behind the miniature chamber.Because the girth difference of each waveguide annulus or racetrack micro-resonance loop, so their resonant wavelength can be different.By design, can make the characteristic absorption wavelength of the designated gas composition in the only corresponding minimum gas to be detected of resonant wavelength of each micro-resonance loop in the array.The wide range laser beam can produce a series of resonance after entering these micro-resonance loop arrays, and wherein the resonant wavelength light of micro-resonance loop array can be downloaded waveguide-coupled output accordingly.At last, each is downloaded waveguide and transports light to corresponding photo-detector, just can determine and calculate the kind and the content of this gas by comparison photo-detector both light intensity difference after gas is by vacuum and minimum gas to be detected.
Advantage of the present invention is mainly reflected in following aspect:
1. can filter out the light of a plurality of characteristic wavelengths of gas to be detected simultaneously.Because the present invention adopts the micro-resonance loop array first, the light of the different characteristic wavelength of gas with various or same gas can be downloaded waveguide-coupled from the micro-resonance loop of resonance separately respectively by the micro-resonance loop array and output to separately photo-detector, therefore, this kind structure can the one-time detection multiple gases or is accurately analyzed the different characteristic spectrum absorbing state of same gas.Can measure the minimum gas detection technique of multiple gases such as spectral technique etc. at present simultaneously and need use huge, expensive spectroanalysis instrument, make the system can't portability.
2. can improve the precision of gas detection.Can accurately select the resonant wavelength of micro-resonance loop by the girth of control micro-resonance loop, and pass through the auxiliary of manufacture craft, the spectrum width that can make the output of micro-resonance loop selectivity is in the pm-nm rank.Because the output optical spectrum is narrow so suddenly, gas also is easy to be detected in the slight absorption of this resonance wave strong point, detection accuracy reaches the PPB level, therefore can solve high toxicity, severe corrosive gas such as a hydrofluoric difficult problem that detector at present commonly used is difficult to detect utmost point low content (less than PPM).
3. improve the integrated level and the portable degree of system.The micro-resonance loop array can utilize large-scale semiconductive manufacture craft such as CMOS (Complementary metal-oxide semiconductor commonly used at present, the complementary type Metal-Oxide Semiconductor) technology is made easily, can also utilize with the photo-detector of extensive manufacture craft compatibility integrated in the making, total system can be integrated on the small chip, therefore, system has small and exquisite, and is light, inexpensive characteristics.
Description of drawings
Fig. 1 is based on the micro-resonance loop array and is used for the synoptic diagram that multiple gases detects;
Fig. 2 is the structural drawing (wherein the direction of arrow is gas flow direction, and the dotted line direction is a propagation path of light) of gas compartment;
Fig. 3 is micro-resonance loop schematic cross-section figure;
Fig. 4 is for detecting the system architecture frame of multiple minimum gas.
Label declaration: 1: laser instrument, 2: transmission light path or optical fiber, 3: gas compartment, 4: extract or the gas injection body device 5: optical fiber-Waveguide coupling arrangement, 6: shared input waveguide or upload waveguide, 7: waveguide annular or runway shape micro-resonance loop, 8: download waveguide, 9: photo-detector;
10: gas inflow catheter, 11: gas valve and vacuum extractor, 12: light path interface, 13: packoff; 14: substrate, 15: insulation course, 16: overlayer.
Embodiment
Below with reference to figure and specific implementation process the present invention is described in further details.
Adopt optical waveguide micro-resonance loop array as spectroscopic instruments, single optical waveguide micro-resonance loop system is made up of the circular ring type of a sealing or racetrack micro-resonance loop and two straight wave guides, wherein a straight wave guide is the light input or uploads waveguide that another root straight wave guide is that light is downloaded waveguide.Vertical range between straight wave guide and the micro-resonance loop is a coupling gap.In optical waveguide micro-resonance loop system, the waveguide bend of straight wave guide and formation micro-resonance loop all has identical sectional dimension and dielectric structure.Waveguide is advanced and when arriving waveguide and annulus adjacent areas, light can be coupled to annulus waveguide, i.e. micro-resonance loop along uploading when light.Light can form the standing wave resonant wavelength during circle transmission in annulus, have only resonant wavelength light could pass through to download waveguide output.The resonant wavelength of micro-resonance loop is determined by following formula:
n
effL＝mλ (2)
Wherein, n
EffBe the effective refractive index of optical waveguide, L is the girth of resonant ring, and m is a resonance level, and λ is a resonant wavelength.Each micro-resonance loop can have a plurality of resonant wavelengths, the adjacent m level and the spacing of m+1 level resonant wavelength be the free spectrum width (Free Spectral Range, FSR).By selecting the girth of micro-resonance loop, can make resonant wavelength in the micro-resonance loop resonance spectrum identical with a characteristic absorption wavelength in the gas absorption spectra to be checked, (see (2) formula, by regulating perimeter L, can make the resonant wavelength of micro-resonance loop identical) with certain absorbing wavelength of gas to be detected, and, can make the wave spectrum width of the resonant wavelength light of download port output be so small to have only tens micromicrons by the manufacture craft of control micro-resonance loop.Therefore, utilize a micro-resonance loop very to filter out a kind of light wave of certain characteristic absorption wavelength of gas to be measured exactly.
In order to separate the characteristic absorption light wave of multiple gases, need to adopt a plurality of micro-resonance loops to form array, make each micro-resonance loop isolate a kind of light of characteristic absorption wavelength of gas.At first, light enters gas compartment after light source sends, and the light wave of a part of wavelength (corresponding to the characteristic spectrum of this gas) is by the gas strong absorption, and the laser after the absorption is transferred to the shared waveguide of uploading.The shared light of uploading in the waveguide can be coupled with the micro-resonance loop array, and wherein corresponding with first micro-resonance loop resonance light can be downloaded by the download waveguide-coupled of first micro-resonance loop, and remaining light wave can continue along uploading waveguide.When light transmission to the second micro-resonance loop, the resonance light corresponding with this micro-resonance loop can be coupled download.And the like, n micro-resonance loop can corresponding n kind gas to be measured.In view of the above, the light of the characteristic wavelength of a kind of gas of the corresponding output of each micro-resonance loop, thereby the micro-resonance loop array can isolate the light of the corresponding characteristic absorption wavelength of every kind of gas in the various mixed gases, thus reach the purpose of beam split.For the resonant wavelength that makes micro-resonance loop is corresponding with the characteristic absorption wavelength of gas, the effective refractive index of the girth of micro-resonance loop or resonant ring waveguide must strict control.(see (2) formula, by regulating perimeter L or effective refractive index n
Eff, can make the resonant wavelength of micro-resonance loop identical with certain absorbing wavelength of gas to be detected, wherein effective refractive index is relevant with the structure and the medium refraction index of waveguide.) by design and micro production technology, can make the resonant wavelength of each micro-resonance loop only comprise a kind of characteristic absorption wavelength of gas.As the device synoptic diagram of Fig. 1 for from multi-wavelength input light, isolating needed a series of wavelength light and be detected.Fig. 2 is the gas compartment synoptic diagram.Gas compartment is by gas container, and gas extraction and device for casting, packoff, light are imported and light output interface composition.Fig. 3 is the schematic cross-section of micro-resonance loop and coupled waveguide thereof in the micro-resonance loop array.The bottom in micro-resonance loop cross section is substrate, generally forms by crystalline silicon, and be insulation course on the substrate, be generally silicon dioxide, be used to stop the basad leakage of light of ducting layer.Be ducting layer on the insulation course, form, be shown as Fig. 3 and upload waveguide that resonant ring, and download the cross section of waveguide is wherein uploaded waveguide and downloaded waveguide and is the coupling spacing with the distance of micro-resonance loop respectively by crystalline silicon.Ducting layer is covered by overlayer such as silicon dioxide.It is pointed out that the micro-resonance loop array also can be by other waveguide material system such as polymer, compositions such as III-V family.
Whole gas detecting system mainly is made up of following equipment: wide range LASER Light Source or continuous tunable laser sources and control circuit, transmission light path, gas compartment, coupling and transmission light path, light-dividing device and photo-detector etc.
At present, the laser of semiconductor the is adjustable diode laser light source can provide near infrared single wavelength laser or a certain wave band of near infrared, its wavelength-tunable scope is 700nm～3000nm, and general most of gas such as the O that studies
2, NO
2, HF, HBr, H
2O, C
2H
2, NH
3, CO, CO
2, H
2S, CH
4, the absorption spectra of HCl etc. all is near infrared.Simultaneously, diode laser is the total solids device, and volume is little, operation at room temperature, and reliability surpasses 5 years, and power can be to the hundreds of milliwatt.The leaded light light path adopts single-mode fiber to come transmitting beam, and laser beam is not subjected to the interference of external environment condition like this, move or the change light path more convenient.Laser Detecting Set is selected the optical semiconductor detector for use, and it has highly sensitive, and reaction velocity is fast, and small volume and less weight is cheap, easily integrated advantage.Micro-resonance loop array and photo-detector can and utilize the CMOS technology of standard to make based on the SOI material system, or select other material such as making such as polymer or sol-gel for use.Wavelength light-dividing device has accurately been arranged, just can utilize wide range LASER Light Source or continuous tunable laser sources input laser, make laser beam pass through gas compartment, and the spectral separation of utilizing the micro-resonance loop array to measure has been come out.Then, light beam is connected on a series of photo-detector by waveguide or optical fiber.The light intensity readings of each photo-detector is made as initial light intensity when gas compartment is vacuum.By the reading on the photo-detector behind the gas to be measured is light intensity after the gas absorption.Because the output of a micro-resonance loop in design in every kind of gas and the micro-resonance loop array is corresponding, be that the predetermined resonant wavelength of micro-resonance loop is consistent with the characteristic absorption optical wavelength of certain gas, if light beam passes through the photo-detector difference of reading of gas front and back greater than preset threshold, illustrate that gas is in this wavelength place strong absorption, the resonant wavelength of this micro-resonance loop is the characteristic absorption optical wavelength of gas, therefore can determine to contain in the gas compartment this kind gas componant.After the structure of micro-resonance loop is determined, its pairing resonant wavelength has also promptly been determined, therefore, in the design and fabrication of micro-resonance loop, can make each micro-resonance loop corresponding, thereby make the absorption of the corresponding a kind of gas of output of this micro-resonance loop with an absorbing wavelength of gas.According to formula (1), the light of having known every kind of characteristic light wavelength correspondence just can calculate the concentration of this kind gas by with not poor by the light intensity readings of photo-detector before and after the gas.The block diagram of whole measuring system is as shown in Figure 4.
Embodiment 1:
Be a specific embodiment below: laser instrument is selected the DL-DFB diode laser of TOPICA company for use, its wavelength-tunable scope is 760nm-3000nm, output power is 2-150mW, light beam output back is connected to gas compartment by single-mode fiber, gas compartment is integrated with optical fiber input and output interface, two interfaces are respectively in the both sides of gas compartment, and its distance is the length of gas compartment, is 100mm in this example.Pressure behind the gas compartment gassy is an atmospheric pressure.Because the light in the optical fiber can be dispersed after gas compartment optic fibre input end mouth enters gas compartment, the light intensity magnitude that optical fiber received that output port connects will with fiber core size, fibre core end surface shape, gas compartment length, and the decay that gas caused is relevant.Suppose that gas compartment is by CO
2, CO, NH
3, H
2S, gas compositions such as HF.They near infrared resonant wavelength are respectively: 1.4 μ m, 1.58 μ m, 1.512 μ m, 1.577 μ m, 1.31 μ m.The micro-resonance loop array is made of SOI (Silicon-On-Insulator) material system, its substrate is a monocrystalline silicon, and thickness is about 750 μ m, and insulation course is a silicon dioxide, thickness is 3 μ m, ducting layer is a monocrystalline silicon, and thickness is 200nm, and the sectional dimension of waveguide is 500nm * 200nm, its effective refractive index is 2.3836, top layer is an overlayer, and material is still silicon dioxide, and thickness is 3 μ m.Upload waveguide and download waveguide and be 300nm at interval with the coupling of micro-resonance loop respectively.The micro-resonance loop array is made up of 5 micro-resonance loop systems, and their radius is respectively 29.27 μ m, 29.18 μ m, 29.40 μ m, 29.46 μ m, 29.22 μ m, the resonant wavelength of respectively corresponding above-mentioned five kinds of gases.The micro-resonance loop array can be made by existing large-scale semiconductive manufacture craft such as CMOS (Complementary metal-oxide semiconductor, complementary type Metal-Oxide Semiconductor) manufacture craft.By the control manufacture craft, the bandwidth of the output resonant wavelength of above-mentioned micro-resonance loop all can be controlled in the 0.5nm.It is pointed out that because a kind of gas has a plurality of resonant wavelengths, and the resonant wavelength of gas with various might overlap each other, therefore, when selecting the micro-resonance loop radius, make a micro-resonance loop only export a kind of absorbing wavelength of gas as far as possible.But,, can utilize two or more resonant rings to export the not resonance characteristics wavelength of gas of the same race, thereby reach the purpose of discerning gas with various exactly if the characteristic spectrum of gas with various has overlapping in the measure spectrum district and can't avoid.Be coupled by optical fiber-waveguide coupler from the optical fiber of gas compartment outgoing and the waveguide of uploading of micro-resonance loop system.Photo-detector realizes that by mixing germanium (Ge-On-Silicon) photo-detector or InGaAs PIN photodiode the detection wavelength coverage is～0.9-1.6 μ m.Mixing germanium (Ge-On-Silicon) photo-detector can utilize CMOS technology and SOI micro-resonance loop array integrated.When the light beam of tunable laser output entered gas compartment and is transferred to the micro-resonance loop array, because the resonant wavelength of the corresponding a kind of gas to be measured of each micro-resonance loop, the photo-detector that is connected with this micro-resonance loop will detect this wavelength place light intensity to be changed.When measuring, at first allow the gas compartment be vacuum, write down the light intensity value of each micro-resonance loop correspondence respectively, allow gas compartment be full of gas to be measured then, write down the light intensity value of each micro-resonance loop correspondence more respectively, according to formula (1) just can obtain respectively each micro-resonance loop the concentration of corresponding gas.
Claims (3)
1. the trace gas detection method based on micro resonance loop array spectrum-dividing technology is characterized in that, concrete steps are:
With wide spectrum light source or continuously the infrared laser that sends of tunable laser by a gas compartment that is used to charge into gas to be measured, gas compartment is provided with the micro-resonance loop array of being made up of micro-resonance loop 2-20 different girths and that be annular that delegation is arranged in order or runway shape outward, because above-mentioned different micro-resonance loop has different resonant wavelengths because of having different girths or refractive index, therefore, can be by the resonant wavelength light in the infrared laser behind the gas compartment by the output of the download waveguide-coupled of corresponding micro-resonance loop, detect the light intensity of coupling output light again by photo-detector, the corresponding photo-detector of the download waveguide of each micro-resonance loop; Again by formula
Calculate the air pressure P of a certain gas to be measured, I is for being detected the light intensity after the light wave that obtains passes through gas, I in the formula by photo-detector
0Pass through gas light intensity before for detect the light wave that obtains by photo-detector, L is infrared laser passes gas to be measured in gas compartment a length, α is the absorption coefficient of this kind gas to be measured, α is a known constant, finally obtains gas concentration to be measured according to the air pressure P of gas to be measured and the corresponding relation of gas concentration to be measured at last.
2. minimum gas detector based on micro resonance loop array spectrum-dividing technology, it is characterized in that, the light source that is used to send infrared laser joins by the light input end of light path or optical fiber and gas compartment, gas compartment is provided with and extracts or the gas injection body device, the light output end of gas compartment by optical fiber-Waveguide coupling arrangement with upload waveguide and join, a plurality of photo-detectors are connected respectively with a plurality of download waveguides, are provided with the micro-resonance loop array of being made up of micro-resonance loop 2-20 different girths and that be annular that delegation is arranged in order or runway shape between the waveguide uploading waveguide and download.
3. the minimum gas detector based on micro resonance loop array spectrum-dividing technology according to claim 2, it is characterized in that, light source adopts infrared laser, output power is 2-150mW, the wavelength of infrared laser is 700nm～3000nm, the effective refractive index of micro-resonance loop waveguide is 2.3836, and the distance of uploading between waveguide and micro-resonance loop and download waveguide and the micro-resonance loop is the coupling interval, and photo-detector adopts mixes the germanium photo-detector.
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| CN106556627B (en) * | 2015-01-22 | 2019-04-26 | 江西师范大学 | Sensor based on nano material |
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| CN105466871A (en) * | 2015-12-21 | 2016-04-06 | 北京邮电大学 | Gas concentration measuring method and sensor |
| CN111837025A (en) * | 2018-03-12 | 2020-10-27 | 关东电化工业株式会社 | Gas analysis method and apparatus |
| US20240142303A1 (en) * | 2021-03-17 | 2024-05-02 | Agency For Science, Technology And Research | Integrated circuit spectrometer |
| CN113776723B (en) * | 2021-09-30 | 2023-09-19 | 云南师范大学 | Optical fiber air pressure detector based on optical coupling change |
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