Micro-electro-mechanical optical device

Details Micro-electro-mechanical optical device Micro-electro-mechanical optical device

1999-09-03

2001-07-24

Nelms, David (Department: 2818)

Semiconductor device manufacturing: process

Making device or circuit responsive to nonelectrical signal

Physical stress responsive

C438S051000, C438S048000

Reexamination Certificate

active

06265239

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to optical communication systems and more particularly, to micro-electro-mechanical optical devices.
DESCRIPTION OF THE RELATED ART
Optical communication systems typically include a variety of optical devices (e.g., light sources, photodetectors, switches, attenuators, mirrors, amplifiers, and filters). The optical devices transmit, modify, or detect optical signals in the optical communications systems. Some optical devices are coupled to micro-electro-mechanical structures (e.g., thermal actuators) forming a micro-electro-mechanical optical device. The term micro-electro-mechanical structure as used in this disclosure refers to a structure that moves mechanically under the control of an electrical signal. The microelectro-mechanical structure moves the optical devices from a first position to a second position.
Typically, both the micro-electro-mechanical structure and the optical device are fabricated by patterning a plurality of material layers formed on a substrate. However, the typical range of motion for the optical device perpendicular to the substrate is limited to the thicknesses of the material layers. In particular, such a limited range of motion for the optical devices also limits the size of the optical device, the angle of rotation for the optical device, or both.
Therefore, methods for increasing the range of motion of an optical device continue to be sought.
SUMMARY OF THE INVENTION
The present invention is directed to a method for pivoting an optical device about one or more axes thereof. In one embodiment of the present invention, springs couple the optical device to the micro-electro-mechanical structure. The micro-electro-mechanical structure lifts the optical device above the plane of the substrate surface. The microelectro-mechanical structure includes an engagement plate. A first end of each spring is coupled to the engagement plate. A second end of each spring is coupled to the optical device.
A portion of the spring near the second end is optionally held on the engagement plate with one or more braces. The braces are made of one or more strips of material. Holding the portion of each spring on the micro-electro-mechanical structure with braces prevents the optical device from moving in a translational direction when such optical device pivots.
After the optical device is lifted above the plane of the substrate surface, an electrostatic field is generated between the lifted optical device and the substrate surface. The electrostatic field is generated by applying a bias voltage between the optical device and a portion of the substrate surface.
The electrostatic field pivots the optical device, deflecting an edge thereof toward the substrate surface. The optical device pivots about an axis defined by the springs. The deflection distance of the optical device depends on the amount of the applied bias voltage.
Both the substrate and the optical device are preferably conductive so that the bias voltage may be applied thereto. When either of the substrate or the optical device are insufficiently conductive to deflect such optical device toward the substrate surface, conductive layers (e.g., electrodes) are optionally formed on regions thereof.
The engagement plate is optionally coupled to one or more intermediate structures which are then coupled to the optical device. The one or more intermediate structures are coupled to both the engagement plate and the optical device with springs. The one or more intermediate structures allow multi-axis rotation for the optical device coupled thereto. A plurality of electrodes are optionally disposed on the substrate surface proximate to both the intermediate structures and the optical device to permit substantially independent rotation of the optical device around the multiple axes.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and do not serve to limit the invention, for which reference should be made to the appended claims.


REFERENCES:
patent: 5903380 (1999-05-01), Motamedi et al.
patent: 5994159 (1999-11-01), Aksyuk et al.
Chen et al.,IEEE, “A Low Voltage Micromachined Optical Switch By Stress-Induced Bending”, pp. 424-428, 1999.
Cowan et al.,SPIE, “Vertical Thermal Actuators for Micro-Opto-Electro-Mechanical Systems”, vol. 3226, pp. 137-146, 1997.

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