Optical: systems and elements – Mirror – With support
Reexamination Certificate
2002-04-15
2003-07-29
Sikder, Mohammad (Department: 2872)
Optical: systems and elements
Mirror
With support
C359S877000, C359S878000
Reexamination Certificate
active
06598985
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a Microelectromechanical System (MEMS) fabricated optical mirror system that is capable of being tilted on two orthogonal axes, by means of electrostatically driven comb drives. Particular application to the use of these mirrors in the deflection of optical space beams is emphasized.
BACKGROUND OF THE INVENTION
Fiber optic communication systems currently employ electro-optic switching systems to route signals at central office switching centers. These electro-optic systems rely on converting the light output from each “incoming” fiber into electrical form, extracting the data content in the resultant electrical signal, then utilizing conventional electrical switches to route the data content to a modulatable optical source that is coupled to a “destination” optical fiber. This detection switching remodulation process is expensive, complex, power consuming, and subject to component failure.
Alternate “All Optical” switching systems, employing mechanically actuated bulk optic and MEMS fabricated devices currently exist. These devices utilize electromagnetic, piezoelectric and electrostatic actuators to physically move prisms, mirrors and portions of optical fibers to affect switching of signals between optical fibers.
In addition fiber-to-fiber switches employing Grating Waveguides, Rowland Circle Gratings, and planar gratings, permit dedicated switching based on optical wavelength.
Cascaded binary tree configurations, employing switchable optical couplers using electrostatically variable index material, (Lithium Niobate and polymers), as well as Mach Zender interferometers utilizing thermoelectric heaters to affect unbalance, are also currently state of the art.
Many of the MEMS switches employ a space-beam deflection system similar to the electrical “Cross Bar” switch common in telephone system. This approach requires that the number of mirrors for a given input/output port count be determined by the square of the port count figure. The overwhelming number of mirrors dictated by this approach exceeds that which can be produced with any realistic process yield, and survive any reasonable operating period.
Except for some of the MEMS electrostatically actuated devices, none of the above methods of optical switching meets the requirements currently being specified for high fiber port count, (up two 1024 by 1024) Optical Cross Connect switches. Problems of cost, reliability, insertion loss, polarization sensitivity, isolation, wavelength dependence, power consumption, and in some instances, switching speed, either individually or collectively mitigate against their use. Accordingly, what is needed is a system and method for overcoming the above-identified issues under the constraint of a simple CMOS-compatible fabrication process.
An optical mirror system design is desired that has high-resolution 2-D scanning capability and deflection capability, made with a surface-micromachining process. In order to achieve high-resolution, large mirror size and rotation angles are necessary.
The present invention addresses such a need.
SUMMARY OF THE INVENTION
An optical mirror system with multi-axis rotational control is disclosed. The mirror system includes an optical surface assembly, and at least one leg assembly coupled to the optical surface assembly. The at least one leg assembly supports the optical surface above a substrate. A system and method in accordance with the present invention can operate with many different actuator mechanisms, including but not limited to, electrostatic, thermal, piezoelectric, and magnetic. An optical mirror system in accordance with the present invention accommodates large mirrors and rotation angles. Scanning mirrors can be made with this technique using standard surface-micromachining processes, or a deep RIE etch process.
A device in accordance with the present invention meets the requirements for a directly scalable, high port count optical switch, utilizing a two mirror per optical I/O port configuration. An optical mirror in accordance with the present invention can be utilized in, but is not limited to, the following applications: optical add-drop multiplexers, wavelength routers, free-space optical interconnects, chip-level optical I/O, optical scanning displays, optical scanner (bar-codes, micro cameras), optical storage read/write heads, laser printers, medical replacement for glasses (incorporated with adaptive optics), medical diagnostic equipment, optical scanning for security applications.
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Fling John J.
Hagelin Paul Merritt
NanoGear
Sawyer Law Group LLP
Sikder Mohammad
LandOfFree
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