GB2208931A - An optically driven mechanical oscillator - Google Patents
An optically driven mechanical oscillator Download PDFInfo
- Publication number
- GB2208931A GB2208931A GB8719591A GB8719591A GB2208931A GB 2208931 A GB2208931 A GB 2208931A GB 8719591 A GB8719591 A GB 8719591A GB 8719591 A GB8719591 A GB 8719591A GB 2208931 A GB2208931 A GB 2208931A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- waveguide
- oscillatory
- arrangement
- point
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003534 oscillatory effect Effects 0.000 claims abstract description 25
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 10
- 239000010703 silicon Substances 0.000 claims abstract description 10
- 230000003287 optical effect Effects 0.000 claims abstract description 9
- 230000008878 coupling Effects 0.000 claims abstract description 7
- 238000010168 coupling process Methods 0.000 claims abstract description 7
- 238000005859 coupling reaction Methods 0.000 claims abstract description 7
- 230000001902 propagating effect Effects 0.000 claims abstract description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000010521 absorption reaction Methods 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 2
- 239000004411 aluminium Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 2
- 238000004544 sputter deposition Methods 0.000 claims description 2
- 239000010410 layer Substances 0.000 claims 1
- 230000010355 oscillation Effects 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 238000005530 etching Methods 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 239000013307 optical fiber Substances 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 230000001934 delay Effects 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
- G01L1/183—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material by measuring variations of frequency of vibrating piezo-resistive material
- G01L1/186—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material by measuring variations of frequency of vibrating piezo-resistive material optical excitation or measuring of vibrations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
- G01L9/0008—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations
- G01L9/0019—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations of a semiconductive element
- G01L9/002—Optical excitation or measuring
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
An opto-mechanical oscillator eg for sensing pressure or tension uses an optical waveguide adjacent and parallel to an oscillatory element of, for instance, thin silicon. Light propagating in the waveguide produces an evanescent field in the gap between waveguide and element, so light is coupled into the element. This light then propagates in the element to a point B at which it is absorbed and generates a thermal wave which in turn produces an elastic wave which causes the point of coupling to move relative to the guide in such a way as to make the element oscillate. Thus the amount of light coupled also oscillates so the light remaining in the waveguide is intensity modulated. <IMAGE>
Description
MECHANICAL OSCILLATOR
This invention relates to an opto-mechanical arrangement.
According to the invention, there is provided an opto-mechanical oscillatory arrangement, which includes an oscillating element made of a material capable of guiding light, which element is mounted adjacent to an optical waveguide, in which light is sed tn propagate along the waveguide, the relative locations of the waveguide and the element being such that some of the light is coupled into the element due to the evanescent field in the gap between the waveguide and the element, in which the light thus coupled into the element is guided from its point of coupling to a further point at which it is absorbed and generates a thermal wave, in which the said thermal wave generates an elastic wave whose propagation in the element causes the point of coupling to move relative to the waveguide1 and in which such movement causes the amount of light coupled to vary in such a way that the element is caused to oscillate.
Thus an important feature of the invention is that light couples across from the waveguide to one point in the silicon element, and is absorbed into heat at the further point.
The preferred materials to be used for the element are silicon or quartz, and the device can be used as a sensor by enabling a parameter to be monitored to influence the element. This varies the oscillatory frequency, and thus also the frequency of the intensity modulation of the light in the waveguide.
An embodiment of the invention will now be described with reference to highly schematic Figs. 1 and 2.
The device includes a micro-machined mechanical oscillatory element, made preferably of silicon or quartz which is positioned close to an optical waveguide, such as an optical fibre or an integrated optic waveguide, such that there is a small gap between them. This element, see Fig. 2, is generally rectangular and is mounted adjacent to an optical waveguide 2, either an integrated optic waveguide as shown or an optical fibre.
Light propagating in the waveguide, as shown by the dotted line, Fig. 1, couples into the oscillatory element 1 at point h vid tie evdrlescerlt field that exists in the gap. Once in the oscillatory element the light is guided by the shape of the material to point B where it is absorbed. This absorption may occur due to a surface plasmon effect due to a metal coating on a buffer layer on the surface of the element, or due to suitable doping of the material.
Where a metallic coating is used zith a silicon element, it can be gold, chrome or aluminium applied by sputtering or evaporation with a silicon dioxide or silicon nitride buffer layer, the thicknesses being varied to get the right match for the frequency of the light to the frequency of the surface wave forming the plasmon. In the case of doping, a suitable dopant is boron, with heavy p+ doping. This increases the absorption by the silicon (of the element 1) of longer wavelength light. The choice depends on the wavelengths to be absorbed. Boron also has the merit that its use facilitates the etching process used in making the oscillatory element when silicon is used.
The absorption of the light which reaches the point B.generates a thermal wave which, in its turn, generates an elastic wave in the element 1. As this elastic wave propagates through the oscillatory element, it causes point A to move relative to the optical waveguide, altering the size of the gap between itself and the optical waveguide. As the gap is reduced, more light is coupled into the element 1, and as the gap is increased less light is coupled into the element 1. The light energy reaching point B is therefore intensity modulated.
The distance between the points A and B is such that the phase of the modulation of the light signal arriving at point B is that needed to cause reinforcement of the elastic wave in the oscillatory element at the natural frequency of the mechanical oscillatory element. Thus illumination of the waveguide at point C with unmoduiated Lutit itiuuus wave light, e.g.
from a laser or a light-emitting diode, causes the element 1 to oscillate at its natural frequency. The remaining light in the waveguide 2 is also intensity modulated at this frequency, and is detected by detector
D.
The element 1, as can be seen from Fig. 2, consists of a generally cruciform portion which forms the oscillatory element proper connected to an outside frame region by four thin beams. The element is made from silicon by micro-etching, and in one case has overall dimensions 1 mm by 0.5 mm. The thickness of this element is 8 m.
The device may be used as a sensor if the mechanical oscillatory element is so designed that its natural frequency can be caused to vary under the influence of a parameter to be monitored. This influence can be exerted on the element 1 by a number of ways, such as pressure and tension. Thus continuous wave illumination of the device produces an intensity modulated output at a frequency characteristic of the value of the parameter to be monitored.
The arrangement described has the merit that no electronic components are needed in the oscillatory element because the required phase delays in the optical mechanical-optical feedback loop are achieved by the shaping of the oscillatory element, and by separating the points at which the light is coupled into the element and light is absorbed. Further, it does not, unlike some prior art sensing systems, need a pulsed light source as the system is self-resonant.
Claims (9)
1. An opto-mechanical oscillatory arrangement, which includes an oscillatory element made of a material capable of guiding light, which element is mounted adjacent to an optical waveguide, in which light is caused to propagate along the waveguide, the relative locations of the waveguide and the element being such that some of the light is coupled into the element due to the evanescent field in the gap between the waveguide and the element, in which the light thus coupled into the element is guided from its point of coupling to a further point at which it is absorbed and generates a thermal wave, in which the said thermal wave generates an elastic wave whose propagation in the element causes the point of coupling to move relative to the waveguide, and in which such movement causes the amount of light coupled to vary in such a way that the element is caused to oscillate.
2. An opto-mechanical oscillatory arrangement, which includes a flat oscillatory element made of silicon and mounted adjacent to and parallel to an optical waveguide, in which light is caused to propagate along the waveguide, the relative locations of the waveguide and the oscillatory element being such that some of the light is coupled into the oscillatory element due to the evanescent field produced in the gap between the waveguide and the element, in which the light thus coupled into the element is guided from its point of coupling to a further point at which it is absorbed and generates a thermal wave, in which the said thermal wave generates an elastic wave whose propagation in the oscillatory element causes the point of coupling to move relative to the waveguide, in which such movement causes the amount of light absorbed to vary in such a way that the element is caused to oscillate, and in which as a result of said oscillation and the variation in absorbence thus effected the light remaining in the waveguide is modulated.
3. An arrangement as claimed in claim 2, in which the oscillatory element has a metallic coating whose thickness and location is such as to produce a surface plasmon effect which causes said absorption of the light.
4. An arrangement as claimed in claim 3, in which a buffer layer or silicon dioxide or silicon nitride separates the oscillatory element from the metal coating.
5. An arrangement as claimed in claim 3 or 4, in which the metallic coating is gold, chrome or aluminium applied by sputtering or evaporation, the thickness being such as to match the frequency of the light to the frequency of the surface wave forming the plasmon.
6. An arrangement as claimed in claim 2, in which the absorption of the light is effected as a result of providing the silicon with a heavy p+ doping of boron.
7. An arrangement as claimed in claim 2, 3, 4, 5, or 6, in which the oscillatory element is cruciform with the point cf absorption at or near the centre poine ut the cross, in which the further point is along one arm of the element, and in which the portion of the cross orthogonal to said one arm is secured by thin arms to an outer rectangular supporting frame.
8. An opto-mechanical oscillatory arrangement substantially as described with reference to the accompanying drawing
9. A sensing arrangement which includes an arrangement as claimed in claim 2, 3, 4, 5, 6, 7, or 8, in which the parameter to be sensed exerts an influence on the dscillatory element, such as to vary the frequency at which it resonates, whereby the light propagating in the waveguide is modulated in accordance with said parameter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8719591A GB2208931B (en) | 1987-08-19 | 1987-08-19 | Mechanical oscilattor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8719591A GB2208931B (en) | 1987-08-19 | 1987-08-19 | Mechanical oscilattor |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8719591D0 GB8719591D0 (en) | 1987-09-23 |
| GB2208931A true GB2208931A (en) | 1989-04-19 |
| GB2208931B GB2208931B (en) | 1991-06-26 |
Family
ID=10622496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8719591A Expired - Fee Related GB2208931B (en) | 1987-08-19 | 1987-08-19 | Mechanical oscilattor |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2208931B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2223311A (en) * | 1988-09-29 | 1990-04-04 | Schlumberger Ind Ltd | Micromachined solid state vibrating element sensors |
| GB2235773A (en) * | 1989-08-30 | 1991-03-13 | Schlumberger Ind Ltd | Indirectly excited resonant element sensor |
| EP0419021A2 (en) * | 1989-08-30 | 1991-03-27 | Schlumberger Industries Limited | Sensors with vibrating elements |
| FR2729232A1 (en) * | 1995-01-10 | 1996-07-12 | Commissariat Energie Atomique | OPTICAL DEVICE FOR OPTOMECHANICAL APPLICATION |
| FR2792410A1 (en) * | 1999-04-14 | 2000-10-20 | Schlumberger Services Petrol | Oil pressure measuring method in oil wells, involves measuring vibration frequency of resonant element placed in oil when it is in stress state close to buckling, based on which oil pressure is deduced |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2146120A (en) * | 1983-09-03 | 1985-04-11 | Gen Electric Co Plc | Photoacoustic force sensor |
| GB2161931A (en) * | 1984-07-17 | 1986-01-22 | Stc Plc | Remote sensor systems |
| GB2182433A (en) * | 1985-11-02 | 1987-05-13 | Stc Plc | Remote sensor |
| GB2185106A (en) * | 1985-12-13 | 1987-07-08 | Gen Electric Co Plc | An optically-driven vibrating sensor |
-
1987
- 1987-08-19 GB GB8719591A patent/GB2208931B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2146120A (en) * | 1983-09-03 | 1985-04-11 | Gen Electric Co Plc | Photoacoustic force sensor |
| GB2161931A (en) * | 1984-07-17 | 1986-01-22 | Stc Plc | Remote sensor systems |
| GB2182433A (en) * | 1985-11-02 | 1987-05-13 | Stc Plc | Remote sensor |
| GB2185106A (en) * | 1985-12-13 | 1987-07-08 | Gen Electric Co Plc | An optically-driven vibrating sensor |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2223311A (en) * | 1988-09-29 | 1990-04-04 | Schlumberger Ind Ltd | Micromachined solid state vibrating element sensors |
| GB2223311B (en) * | 1988-09-29 | 1992-04-08 | Schlumberger Ind Ltd | Sensors |
| GB2235773A (en) * | 1989-08-30 | 1991-03-13 | Schlumberger Ind Ltd | Indirectly excited resonant element sensor |
| EP0419021A2 (en) * | 1989-08-30 | 1991-03-27 | Schlumberger Industries Limited | Sensors with vibrating elements |
| EP0419021A3 (en) * | 1989-08-30 | 1991-10-09 | Schlumberger Industries Limited | Sensors with vibrating elements |
| US5105665A (en) * | 1989-08-30 | 1992-04-21 | Schlumberger Industries Limited | Sensors |
| GB2235773B (en) * | 1989-08-30 | 1993-12-22 | Schlumberger Ind Ltd | Sensors |
| FR2729232A1 (en) * | 1995-01-10 | 1996-07-12 | Commissariat Energie Atomique | OPTICAL DEVICE FOR OPTOMECHANICAL APPLICATION |
| EP0722103A1 (en) * | 1995-01-10 | 1996-07-17 | Commissariat A L'energie Atomique | Optical apparatus for opto-mechanical application |
| FR2792410A1 (en) * | 1999-04-14 | 2000-10-20 | Schlumberger Services Petrol | Oil pressure measuring method in oil wells, involves measuring vibration frequency of resonant element placed in oil when it is in stress state close to buckling, based on which oil pressure is deduced |
| WO2000063664A1 (en) * | 1999-04-14 | 2000-10-26 | Schlumberger Technology B.V. | A method of measuring pressure by means of a pressure gauge having a resonant element |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8719591D0 (en) | 1987-09-23 |
| GB2208931B (en) | 1991-06-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |