Article comprising an optical fiber attached to a micromechanical device

• US 5,831,262 A
• Filed: 06/27/1997
• Issued: 11/03/1998
• Est. Priority Date: 06/27/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Walker, James A., Greywall, Dennis S.
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US08/883,740
• Time in Patent Office: 494 Days
• Field of Search: 250/227.14, 250/227.22, 250/227.24, 250/229, 250/231.1, 250/231.19, 250/227.25, 340/555-557
• US Class Current: 250/227.14
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 6/241 Light guide terminations
• CPC Class Codes: G02B 6/264 with optical elements between opposed fibre ends which perform a function other than beam splitting having lens focusing means G02B6/32; utilising prism or grating G02B6/34
• CPC Class Codes: G02B 6/3516 the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Abstract

An article having an optical fiber integrally attached to a micro-device having spaced movable and nonmoving layers suitable for creating optical interference effects is disclosed. In one configuration, the micro-device is suitable for optical modulation, wherein the movable layer is electrostatically actuated to move towards the nonmoving layer. Such movement changes the size of the gap between the layers, resulting in a change in micro-device reflectivity. An optical signal is modulated by controlling micro-device reflectivity via a controlled voltage source. In a second configuration, the micro-device is suitable for measuring pressure. For pressure measurement, the movable membrane moves in response to pressure changes. The change in membrane position again results in a change in micro-device reflectivity. Reflectivity is correlatable to pressure. In a third configuration, the micro-device is suitable for measuring temperature. In the third configuration, the movable membrane is isolated from pressure effects by the addition of an evacuated cavity located beneath the membrane. The region between the movable and nonmoving layers is gas filled. Changes in gas pressure due to changes in gas temperature cause the movable layer to move, affecting micro-device reflectivity. Reflectivity is correlatable to temperature.

Claims

1. An article having an optical fiber integrally attached to a micro-device, the article comprising:

a micro-device having spaced movable and nonmoving layers;

an optical fiber attached to the micro-device, the optical fiber having an optical core in optical communication with the nomnoving layer and the movable layer; and

an integrating arrangement for attaching the optical fiber to the micro-device, wherein the integrating arrangement comprises a layer of adhesive that is index-matched to a refractive index of the optical core, wherein,

the movable layer is physically adapted for moving relative to the nonmoving layer under the influence of an actuating force, such that the relative movement changes the space between the movable and nonmoving layers so that micro-device reflectivity changes.

2. The article of claim 1, and further wherein the integrating arrangement includes a layer of glass that is disposed on the nonmoving layer.

3. The article of claim 1, and further wherein the movable layer has damping holes.

4. The article of claim 3, and further wherein the actuating force is an electrostatic force generated across the movable and nonmoving layers as a result of an applied voltage from a controlled voltage source.

5. The article of claim 1, and further wherein the actuating force is a pressure exerted by a fluid that is in contact with the movable layer.

6. The article of claim 5, and further comprising an instrumentality for relating changes in reflectivity to changes in the pressure exerted by the fluid.

7. The article of claim 6, and further wherein the space between the movable and nonmoving layers is filled with a gas.

8. The article of claim 7, and further wherein the fluid is characterized by a substantially constant temperature.

9. The article of claim 8, and further wherein the fluid is blood.

10. The article of claim 6, and further wherein the space between the movable layer and the nonmoving layer is in the range of from about 0.1 to 5.0 microns.

11. The article of claim 6, and further wherein the movable layer is characterized by a tensile stress that is in the range of from about 0 to 1000 MPa.

12. The article of claim 6, and further wherein the movable layer has a cross-sectional area within the range of from about 500 to 100,000 square microns.

13. The article of claim 1, wherein the movable layer is characterized by a first side and a second side, and wherein a chamber is defined between the nonmoving layer and the first side of the movable layer, the article further comprising an evacuated cavity located on the second side of the movable layer.

14. The article of claim 13, and further wherein the chamber contains a gas.

15. The article of claim 14, and further wherein the actuating force is a pressure exerted by the gas on the movable layer, which pressure varies only in response to temperature changes in the gas.

16. The article of claim 15, and further comprising means for relating changes in reflectivity to changes in the temperature of the gas.

17. The article of claim 16, and further wherein the space between the movable layer and the nonmoving layer is in the range of from about 0.1 to 5.0 microns.

18. The article of claim 16, and further wherein the movable layer is characterized by a tensile stress that is in the range of from about 0 to 1000 MPa.

19. The article of claim 16, and further wherein the movable layer has a circular shape and has a diameter in the range of from about 500 to 100,000 square microns.

20. The article of claim 1, and further comprising a semiconductor wafer, wherein the micro-device is disposed on the semiconductor wafer.

21. The article of claim 20, wherein the micro-device is configured for measuring pressure, and further comprising a second micro-device and integrally attached optical fiber, wherein, the second micro-device is configured for measuring temperature.

22. A method for measuring at least a change in a value of a physical condition selected from the group consisting of pressure and temperature, comprising the steps of:

forming a device having a movable layer that moves in response to the change in the physical condition, the device having a variable reflectivity, wherein the reflectivity varies as a function of the movement of the movable layer;

delivering an incoming optical signal to the device, the incoming optical signal having a first amplitude; and

measuring a second amplitude of a portion of the incoming optical signal returned from the device as an outgoing optical signal.

23. The method of claim 22, and further comprising the step of developing a correlation between the second amplitude of the outgoing optical signal and the value of the physical condition.

24. The method of claim 23, and further comprising the step of determining the value of the physical condition corresponding to the second measured amplitude by using the correlation.

25. The method of claim 22, wherein the step of forming further comprises the steps of forming a sealed chamber on a first side of the movable layer between the movable layer and a nonmoving layer.

26. The method of claim 25, wherein the step of forming further comprises filling the sealed chamber with a gas.

27. The method of claim 26, wherein the step of forming further comprising forming a chamber on a second side of the movable layer, wherein the chamber is evacuated.

28. A method for making a micro-device suitable for measuring a change in a value of a physical condition selected from the group consisting of pressure and temperature, comprising the step of:

forming a movable layer spaced from a nonmoving layer, the space therebetween defining a sealed chamber, wherein, the sealed chamber is formed by;

depositing a first layer on a support;

depositing a rapidly-etchable layer on the first layer;

patterning the rapidly-etchable layer into a pill having at least one arm extending therefrom, wherein, the pill is patterned over a first region of the first layer at which the movable layer is to be formed;

depositing a second layer over the patterned rapidly-etchable layer; and

delivering etchant to the arms and the support;

wherein, the etchant etches away the arms forming channels, which channels allow etchant to be delivered to the pill for its removal, thereby forming the sealed chamber, and further wherein, the etchant etches away a portion of the support beneath the first region of the first layer, thereby releasing the first region of the first layer to form the movable layer.

29. The method of claim 28, and further comprising the steps of:

depositing a layer of glass on the second layer; and

forming access wells through the glass layer communication with the arms;

wherein, etchant is delivered to the arms via the access wells.

30. The method of claim 29, and further comprising the step of:

attaching an optical fiber having an optical core to the glass layer using an adhesive, wherein, the adhesive and the glass layer have respective first and second indices of refraction that are about equal to an index of refraction of the optical core.