CN102426268A - MEMS (Micro-Electro-Mechanical Systems) microaccelerometer based on acousto-optic effect - Google Patents
MEMS (Micro-Electro-Mechanical Systems) microaccelerometer based on acousto-optic effect Download PDFInfo
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- CN102426268A CN102426268A CN2011103508144A CN201110350814A CN102426268A CN 102426268 A CN102426268 A CN 102426268A CN 2011103508144 A CN2011103508144 A CN 2011103508144A CN 201110350814 A CN201110350814 A CN 201110350814A CN 102426268 A CN102426268 A CN 102426268A
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Abstract
The invention relates to an MEMS (Micro-Electro-Mechanical Systems) microaccelerometer based on an acousto-optic effect, which comprises a laser, an optical waveguide system, an acousto-optic frequency shifter based on plate waves and a photoelectric detector, wherein the optical waveguide system comprises a single-mode rectangular optical waveguide, a tapered optical waveguide, a waveguide polarizer and a waveguide reflecting mirror. The optical waveguide system and the acousto-optic frequency shifter based on the plate waves are integrated on a silicon slice through an MEMS micromachining technology to constitute an acceleration sensitive structure. An input end of the acceleration sensitive structure is connected with the laser, and an output end of the acceleration sensitive structure is connected with the photoelectric detector. In the acceleration sensitive structure, light guide waves penetrate through a sound field excited by the acousto-optic frequency shifter to take Raman type acousto-optic diffraction, +/-n level diffraction light is extracted to carry out superposed frequency mixing to generate photo-beat signals with certain frequency, and is finally output to the photoelectric detector, and the change of acceleration is detected through detecting the frequency change of the photo-beat signals. The microaccelerometer disclosed by the invention is based on a new acceleration detection principle, and has the characteristics of high sensitivity and accurate digital output.
Description
Technical field
The present invention relates to the MEMS miniature acceleration sensor, belong to the little inertia device field in the MEMS (MEMS).
Background technology
The micro-machine acceleration transducer development is very fast, and various ways such as condenser type, pressure resistance type, piezoelectric type, resonant mode, thermal convection formula, tunnel and field emission formula are arranged.What application was maximum at present is condenser type and pressure resistance type MEMS miniature acceleration sensor.The capacitance type minitype acceleration transducer since its influenced by temperature, electromagnetic radiation etc. bigger, so its resolving power generally is limited in the mg magnitude.Pressure resistance type miniature acceleration sensor temperature influence is serious, and its resolving power is lower than capacitance type minitype acceleration transducer.The resonance miniature acceleration transducer is a power frequency characteristic of utilizing the beam that shakes, detects extraneous acceleration through detecting resonance frequency, and this acceleration detection precision is higher.The thermal convection type acceleration transducer sensitivity that declines is lower, and response speed is very slow.Tunnel type and the field emission type acceleration transducer theory that declines has high sensitivity, but problems such as the physical presence linearity is not high, FEEDBACK CONTROL complicacy.Compare with many forms, have characteristics such as highly sensitive, accurate numeral output based on the MEMS miniature acceleration sensor of acoustooptic effect.
Utility model patent 03200395.1 has been described a kind of mixed type integrated optics acceleration detector based on the acoustooptic modulation principle.Its cardinal principle is to utilize integrated optics technique on substrate, to make a resonator cavity; The optical fiber harmonic oscillator is arranged on the resonator cavity signal arm; Harmonic oscillator makes the light in signal arm and the reference arm produce phase differential under the acceleration effect; This phase differential comes balance by the acousto-optic phase-modulator on the reference arm, estimates the size of acceleration with the signal magnitude that applies on the acousto-optic phase-modulator.
Summary of the invention
The objective of the invention is to detect, propose a kind of acceleration transducer of new working mechanism, to improve the sensitivity of acceleration transducer based on acoustooptic effect and optical frequency heterodyne.
Technical scheme of the present invention is following:
Sensor of the present invention comprises laser instrument, optical waveguide systems, based on the acousto-optic frequency shifters and the photodetector of Lamb wave.Said optical waveguide systems, be integrated on the silicon base through the MEMS micro-processing technology, constitute the acceleration sensitive structure based on the acousto-optic frequency shifters of Lamb wave.The input end of acceleration sensitive structure links to each other with laser instrument, and output terminal links to each other with photodetector.Said optical waveguide systems guided laser passes the sound field that the Lamb wave acousto-optic frequency shifters excites; The raman type acoustooptic diffraction takes place; And behind acoustooptic diffraction, extract ± n order diffraction light superposes and produces the photo-beat signal and output to photodetector, comes the variation of sense acceleration through the variation of detection ± n order diffraction optical frequency difference.
Said optical waveguide systems comprises the waveguide of single mode rectangular light, conical optical waveguide, waveguide polarizer and waveguide reflector; It mainly acts on is that the incident light of the single linear polarization of guiding passes frequency shifter sound field generation acoustooptic diffraction, and extracts senior diffraction light and superpose and output to photodetector after the mixing.The waveguide of one section single mode rectangular light is connected to the small-caliber end of conical optical waveguide, and the guided laser bundle gets into conical optical waveguide, and at rectangular light waveguide segment generation acoustooptic diffraction; Place, conical optical waveguide heavy caliber end both sides of the edge connects the waveguide of two sections single mode rectangular light, the finally synthetic one section single mode rectangular light waveguide segment of two sections single mode rectangular light waveguide; Be connected in the three sections single mode rectangular light waveguide before and after the conical optical waveguide and be connected with a waveguide polarizer respectively; Waveguide reflector is at the heavy caliber end on the conical optical waveguide and between the waveguide of two sections single mode rectangular light.
Said raman type acousto-optic frequency shifters based on Lamb wave is the piezoelectricity thin-slab construction; It is made up of the piezoelectricity thin plate, interdigital electrode, absorbent treatment, conical optical waveguide and the mass that utilize the MEMS fabrication techniques, can on the piezoelectricity thin plate, inspire flexural plate wave through interdigital electrode; Said piezoelectricity thin plate is to form through on the optical waveguide covering, covering piezoelectric layer, is a bottom surface middle strip thin-slab construction that has removed silicon base except that two ends; Two absorbent treatments are positioned at the two ends of piezoelectricity thin plate length direction, interdigital electrode between two absorbent treatments of piezoelectric layer surface, the rectangular length direction of the parallel piezoelectricity of its bus-bar; Conical optical waveguide is the conical optical waveguide of optical waveguide systems, is positioned under the piezoelectric layer of piezoelectricity thin plate one end, and the axis of conical optical waveguide is vertical with the length direction of piezoelectricity thin plate, and the guided laser bundle passes acousto-optic frequency shifters along the direction of vertical piezoelectricity thin plate length; Mass is positioned at centre position, piezoelectricity thin plate bottom surface.Light beam passes the flexural plate wave sound field in the direction of the vertical thin plate length in optical waveguide guiding lower edge, and acoustooptic diffraction takes place, and the diffraction light frequency changes with the variation of frequency of sound wave.Under extraneous acceleration effect, the frequency of operation of this frequency shifter changes, and then exports the diffraction light frequency and also changes.
Sensor of the present invention passes the sound field that the Lamb wave acousto-optic frequency shifters excites by the optical waveguide systems guided laser; The raman type acoustooptic diffraction takes place; And behind acoustooptic diffraction, extract ± n order diffraction light superposes and produces the photo-beat signal and output to photodetector, comes the variation of sense acceleration through the variation of detection ± n order diffraction optical frequency difference.
According to the acoustooptic effect principle; N order diffraction light frequency changes n* Δ f when frequency shifter shift frequency amount changes delta f; Therefore after the optical superposition of general ± n order diffraction the photo-beat signal frequency that produces is changed 2n* Δ f; The variation of the frequency through detecting this photo-beat comes the variation of sense acceleration, and n large sensor sensitivity more is high more.
It is thus clear that; The present invention is based on the acceleration transducer of a kind of new working mechanism of raman type acoustooptic diffraction principle proposition; Acceleration causes the variation of Lamb wave frequency shifter shift frequency amount, and through acoustooptic effect, the variation of Lamb wave frequency shifter shift frequency amount is converted into the variation of diffraction light frequency; The diffraction light frequency variation obtains amplifying simultaneously, and the photo-beat frequency that produces through the optical superposition of detection ± n order diffraction realizes the measurement to acceleration.The present invention is owing to adopted optical waveguide difference frequency detection system and light integrated technology, the sensitivity that has improved accelerometer.
Description of drawings
Fig. 1 is a structural principle synoptic diagram of the present invention
Fig. 2 is the vertical view of acceleration sensitive structure
Fig. 3 is the cut-open view at 1 place, Fig. 2 middle section
Fig. 4 is the cut-open view at 2 places, Fig. 2 middle section
Fig. 5 is the cut-open view at 3 places, Fig. 4 middle section
Among the figure: 1. silicon base, 2. siliceous gauge block, 3. optical waveguide covering, 4. conical optical waveguide; 5 zinc paste or aluminium nitride piezoelectric layer, 6. interdigital electrode, 7. waveguide polarizer, 8. waveguide reflector; 9. space, 10. single mode rectangular light waveguide, 11. single mode rectangular light waveguides, 12. absorbent treatments.
Embodiment
Referring to Fig. 1, acceleration transducer of the present invention comprises laser instrument, optical waveguide systems, based on the acousto-optic frequency shifters and the photodetector of Lamb wave.Visible in conjunction with Fig. 2-Fig. 5; Optical waveguide systems and be to be integrated on the silicon base through the MEMS micro-processing technology based on the acousto-optic frequency shifters of Lamb wave; Constitute the acceleration sensitive structure, acceleration sensitive structure input end is Fig. 5 left end optical waveguide, links to each other with laser instrument; Output terminal is Fig. 5 right-hand member optical waveguide, links to each other with photodetector.The optical waveguide systems guided laser passes the sound field that the Lamb wave acousto-optic frequency shifters excites; The raman type acoustooptic diffraction takes place; And behind acoustooptic diffraction, extract ± n order diffraction light superposes and produces the photo-beat signal and output to photodetector, comes the variation of sense acceleration through the variation of detection ± n order diffraction optical frequency difference.
The concrete structure of acceleration sensitive structure is referring to Fig. 1-Fig. 5, and wherein optical waveguide systems comprises single mode rectangular light waveguide 10, conical optical waveguide 4, waveguide polarizer 7 and waveguide reflector 8 referring to Fig. 5, and they are fabricated on the silicon chip.Single mode rectangular light waveguide 10 is connected to the small-caliber end of conical optical waveguide 4, and the guided laser bundle gets into conical optical waveguide, and at rectangular light waveguide segment generation acoustooptic diffraction.The place, heavy caliber end both sides of the edge of conical optical waveguide 4 connects the finally synthetic one section single mode rectangular light waveguide segment of 11, two sections single mode rectangular light of two sections single mode rectangular light waveguide waveguide.Be connected in three sections single mode rectangular light waveguide 10 and 11 of conical optical waveguide 4 front and back and be connected with a waveguide polarizer 7 respectively.Waveguide reflector 8 is at the heavy caliber end on the conical optical waveguide and between the waveguide of two sections single mode rectangular light.
Referring to Fig. 2, Fig. 3 and Fig. 4; On silicon base 1; Interdigital electrode 6, zinc paste or aluminium nitride piezoelectric layer 5, absorbent treatment 12, conical optical waveguide 4 and mass 2 constituted one can sensitive acceleration the Lamb wave acousto-optic frequency shifters; Optical waveguide covering 3 has been formed a strip piezoelectricity thin plate with piezoelectric layer 5, and two absorbent treatments 12 are positioned at the two ends of piezoelectricity thin plate length direction, and interdigital electrode is between two absorbent treatments 12 of piezoelectric layer surface; Conical optical waveguide 4 is positioned under the piezoelectric layer 5, and mass 2 is positioned at below, piezoelectricity thin plate bottom surface middle.
Its concrete structure and manufacturing process are: at first on silicon base 1, produce conical optical waveguide and optical waveguide covering 3; Deposition piezoelectric membrane on the optical waveguide covering then, and be elongate in shape with the piezoelectric membrane etching, forming piezoelectric layer 5, its length direction is vertical with tapered transmission line 4 axis, rectangular end covering tapered transmission line 4; On the strip piezoelectric membrane that etches, make interdigital electrode 6 again and be positioned at the rectangular two ends of piezoelectric layer with 12, two absorbent treatments 12 of absorbent treatment, interdigital electrode be positioned at piezoelectric layer rectangular on, between two absorbent treatments, the rectangular length direction of the parallel piezoelectricity of its bus-bar; At last from the silicon chip of the rectangular overlay area of silicon base 1 back-etching attenuate piezoelectricity; Remaining waveguide covering and piezoelectric layer are formed the piezoelectricity thin plate of strip; Middle is reserved one as mass 2 below piezoelectricity thin plate bottom surface; Etch space 9 in both sides along its length at the piezoelectricity thin plate, strengthen the susceptibility of thin-slab construction to acceleration, final completion is based on the making of the raman type acousto-optic frequency shifters of Lamb wave.
This Lamb wave acousto-optic frequency shifters can inspire flexural plate wave through interdigital electrode 6 in the thin-slab construction that piezoelectric layer 5 and waveguide covering 3 are formed.Under the acceleration effect, mass 2 causes that thin-slab construction receives stress-strain, and the frequency of operation of Lamb wave frequency shifter promptly changes.
Referring to Fig. 5; The laser coupled that lasing light emitter sends is advanced single mode rectangular light waveguide 10, gets into conical optical waveguide 4 through waveguide polarizer 7 backs, and light beam passes the sound field that the Lamb wave frequency shifter produces; And generation raman type acoustooptic diffraction; The mixing (n desirable 1 ~ 5, specifically depend on the circumstances) of coming out to superpose of single mode rectangular light waveguide 11 general ± n order diffraction light extractions produces a photo-beat signal.Waveguide reflector 8 is used to eliminate 0-± (n-1) diffraction lights at different levels right ± interference of n order diffraction optical superposition.According to the characteristics of acoustooptic effect, the frequency of the photo-beat signal that the optical superposition of ± n order diffraction produces is 2n*f
a, f wherein
aBe sound Lamb wave frequency, when acceleration caused flexural plate wave frequencies of propagation changes delta f, then this photo-beat signal frequency changed 2n* Δ f, so this acceleration transducer has very high sensitivity.
The mixing of coming out to superpose of single mode rectangular light waveguide 11 general ± n order diffraction light extractions produces a photo-beat signal, and this photo-beat signal outputs to photodetector, detects the variation that the change of frequency of photodetector output electric signal can be measured acceleration.
Claims (3)
1. based on the MEMS miniature acceleration sensor of acoustooptic effect, comprise laser instrument, optical waveguide systems, based on the acousto-optic frequency shifters and the photodetector of Lamb wave; It is characterized in that: said optical waveguide systems, be to be integrated on the silicon base, constitute the acceleration sensitive structure through the MEMS micro-processing technology based on the acousto-optic frequency shifters of Lamb wave; Said acceleration sensitive structure input end links to each other with laser instrument, and output terminal links to each other with photodetector; Said optical waveguide systems guided laser passes the sound field that the Lamb wave acousto-optic frequency shifters excites; The raman type acoustooptic diffraction takes place; And behind acoustooptic diffraction, extract ± n order diffraction light superposes and produces the photo-beat signal and output to photodetector, comes the variation of sense acceleration through the variation of detection ± n order diffraction optical frequency difference.
2. the MEMS miniature acceleration sensor based on acoustooptic effect according to claim 1 is characterized in that: said optical waveguide systems comprises the waveguide of single mode rectangular light, conical optical waveguide, waveguide polarizer and waveguide reflector; The waveguide of one section single mode rectangular light is connected to the small-caliber end of conical optical waveguide, and the guided laser bundle gets into conical optical waveguide, and at rectangular light waveguide segment generation acoustooptic diffraction; Place, conical optical waveguide heavy caliber end both sides of the edge connects the waveguide of two sections single mode rectangular light, the finally synthetic one section single mode rectangular light waveguide segment of two sections single mode rectangular light waveguide; Be connected in the three sections single mode rectangular light waveguide before and after the conical optical waveguide and be connected with a waveguide polarizer respectively; Waveguide reflector is at the heavy caliber end on the conical optical waveguide and between the waveguide of two sections single mode rectangular light.
3. the MEMS miniature acceleration sensor based on acoustooptic effect according to claim 2; It is characterized in that: said raman type acousto-optic frequency shifters based on Lamb wave is the piezoelectricity thin-slab construction; It is made up of the piezoelectricity thin plate, interdigital electrode, absorbent treatment, conical optical waveguide and the mass that utilize the MEMS fabrication techniques, can on the piezoelectricity thin plate, inspire flexural plate wave through interdigital electrode; Said piezoelectricity thin plate is to form through on the optical waveguide covering, covering piezoelectric layer, is a bottom surface middle strip thin-slab construction that has removed silicon base except that two ends; Two absorbent treatments are positioned at the two ends of piezoelectricity thin plate length direction, interdigital electrode between two absorbent treatments of piezoelectric layer surface, the rectangular length direction of the parallel piezoelectricity of its bus-bar; Conical optical waveguide is the conical optical waveguide of optical waveguide systems, is positioned under the piezoelectric layer of piezoelectricity thin plate one end, and the axis of conical optical waveguide is vertical with the length direction of piezoelectricity thin plate, and the guided laser bundle passes acousto-optic frequency shifters along the direction of vertical piezoelectricity thin plate length; Mass is positioned at centre position, piezoelectricity thin plate bottom surface.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103486972A (en) * | 2013-09-11 | 2014-01-01 | 北京航空航天大学 | Laser feedback interference integrated micro-displacement measuring system with phase modulation function |
| CN105182000A (en) * | 2015-05-30 | 2015-12-23 | 浙江大学 | Three-optical-path signal compensation system in optical MEMS accelerometer and method thereof |
| CN114966110A (en) * | 2022-04-26 | 2022-08-30 | 浙江大学 | non-Hermite singular point optical microcavity acceleration sensor |
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| CN1847857A (en) * | 2005-04-15 | 2006-10-18 | 威海双丰电子集团有限公司 | Capacitor MEMS acceleration sensor |
| CN1884972A (en) * | 2006-07-12 | 2006-12-27 | 北京理工大学 | Micro photo-electro-mechanical gyro |
| CN1987486A (en) * | 2006-12-26 | 2007-06-27 | 清华大学 | Integrated optic grating interference micro mechanical acceleration sensor and its producing method |
| US20100257933A1 (en) * | 2007-07-24 | 2010-10-14 | Nxp B.V. | Multi-axial linear and rotational displacement sensor |
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2011
- 2011-11-09 CN CN2011103508144A patent/CN102426268A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1847857A (en) * | 2005-04-15 | 2006-10-18 | 威海双丰电子集团有限公司 | Capacitor MEMS acceleration sensor |
| CN1884972A (en) * | 2006-07-12 | 2006-12-27 | 北京理工大学 | Micro photo-electro-mechanical gyro |
| CN1987486A (en) * | 2006-12-26 | 2007-06-27 | 清华大学 | Integrated optic grating interference micro mechanical acceleration sensor and its producing method |
| US20100257933A1 (en) * | 2007-07-24 | 2010-10-14 | Nxp B.V. | Multi-axial linear and rotational displacement sensor |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103486972A (en) * | 2013-09-11 | 2014-01-01 | 北京航空航天大学 | Laser feedback interference integrated micro-displacement measuring system with phase modulation function |
| CN105182000A (en) * | 2015-05-30 | 2015-12-23 | 浙江大学 | Three-optical-path signal compensation system in optical MEMS accelerometer and method thereof |
| CN105182000B (en) * | 2015-05-30 | 2018-05-22 | 浙江大学 | Three optical path signal compensation systems and its method in optical MEMS accelerometer |
| CN114966110A (en) * | 2022-04-26 | 2022-08-30 | 浙江大学 | non-Hermite singular point optical microcavity acceleration sensor |
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Application publication date: 20120425 |