Optical: systems and elements – Optical modulator
Reexamination Certificate
2002-03-01
2004-08-31
Thompson, Tim (Department: 2873)
Optical: systems and elements
Optical modulator
C359S290000, C359S291000, C385S033000, C385S039000
Reexamination Certificate
active
06785033
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to optical devices and, more specifically, to an optical attenuating device, a method of manufacture therefor, and a system including the same.
BACKGROUND OF THE INVENTION
Advances in thin film technology have enabled the development of sophisticated integrated circuits. This advanced semiconductor technology has also been leveraged to create microelectro-mechanical systems (MEMS) structures. Many different varieties of MEMS devices have been created, including micro-sensors, micro-gears and micro-motors. MEMS devices can be employed in a variety of applications, including optical applications that employ MEMS light valves, switches and shutters. MEMS devices have been developed for a wide variety of applications because they provide the advantages of high reliability, extremely small size and applicability to conventional lithographic fabrication techniques.
MEMS structures have also been employed to provide optical attenuation. Optical attenuation can be used to reduce signal power. For instance, attenuation may be required where a signal contains several wavelengths of light and one channel is overpowered to the extent that optical detectors may become saturated. Another example might be an application in which signals originate from several different locations and must be combined together to achieve one or more signals having the same power level. Optical attenuators are also employed for signal gain flattening, such as in dynamic gain equalizers, which can independently address multiple channels of different wavelengths. For example, one or more signals of different wavelengths can be guided into a single fiber such that MEMS optical attenuators integral to the gain equalizer can either address all of the light in that fiber or split the light out into different channels to be independently addressed.
Previous attempts at optical attenuation often employed a lens, a collimator and a reflective membrane deformable in response to an applied voltage. The overpowered signal was guided through the lens, collimated, and reflected off the membrane. Such devices were capable of adequate attenuation performance, however, only at the expense of extensive assembly and alignment obstacles. Misalignment problems generally arise as a result of external hardware and support structure securing the fibers, lens, and membrane in fixed spatial relation to one another. For example, undesirable signal disruption may emanate from (1) misalignment of the input signal fiber with the lens, (2) misalignment of the collimated signal with the membrane, (3) misalignment of the input signal fiber in relation to the output signal fiber, and (4) insertion loss at the fiber/device interfaces.
Attempts to solve this problem involved discrete components with either movable shutter blades, cantilevered mirrors or deformable drumhead membranes with separately aligned lens and discrete fibers. Some improvement materialized with meticulous manual assembly and the advent of automating the assembly of individually constructed units. These attempts, however, failed to completely resolve issues concerning high cost, low throughput, and extensive use of manpower and expensive capital equipment to assemble the device with precise alignment.
Accordingly, what is needed in the art is an optical attenuator device and method of manufacture therefor that avoids the disadvantages associated with the devices currently known in the art.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides an optical device, a method of manufacture therefor, and an optical system including the same. The optical device may include a membrane configured to be electrically deformable and reflective. The membrane may further be positioned over a cavity located within a substrate. The device may additionally include a transmissive spacer coupled to the substrate, and a lens coupled to the transmissive spacer and optically aligned with the membrane.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.
REFERENCES:
patent: 5526172 (1996-06-01), Kanack
patent: 6487342 (2002-11-01), Wu et al.
patent: 2002/0076151 (2002-06-01), Kinard et al
Meyers Mark M.
Xu Daxue
Agere Systems Inc.
Thompson Tim
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