Optical: systems and elements – Optical modulator – Light wave directional modulation
Reexamination Certificate
2001-04-25
2003-10-28
Ben, Loha (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave directional modulation
C359S198100, C359S223100, C385S018000
Reexamination Certificate
active
06639713
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to micromachines for use in optical systems, and more specifically, to silicon micromachined optical attenuators and switches for a plurality of light beams propagating along a respective plurality of beam paths.
2. Description of the Related Art
Micro-electro-mechanical systems (MEMS) are physically small systems with both electrical and mechanical components, and with dimensions on the order of microns. To achieve the small dimensions of the various components, MEMS are typically fabricated using techniques which were developed in part for integrated circuit fabrication. MEMS-based devices are found in an increasing number of applications, such as inkjet-printer cartridges, accelerometers that deploy car airbags, and other sensors and actuators. MEMS has developed into a growth industry with an estimated yearly market of tens of billions of dollars. In addition, MEMS-based optical systems, such as optical attenuators and switches, are becoming increasingly important in the field of telecommunications and computer networks.
A variable optical attenuator (VOA) is a device which can adjust the optical signal power passing through an optical fiber transmission circuit, such as dense wavelength-division multiplexing (DWDM) systems. Because the amount of light passing through an optical fiber depends on the wavelength of the light, VOAs are often needed to ensure power equalization of the individual wavelengths by adjusting the intensity for each wavelength. VOAs used in fiber optic communications system may use absorptive or reflective techniques to controllably adjust the transmitted power.
An optical switch is a device which can selectively switch optical signals from one optical circuit to another, and are typically used in optical systems such as optical add/drop multiplexers (OADMs). Various technologies can be used in optical switches, including, but not limited to, physically shifting an optical fiber to drive one or more alternative fibers, physically moving a reflective element, electro-optic effects, or magneto-optic effects.
MEMS technology has been identified as being able to satisfy the requirements of optical systems in the telecommunications and computer networking fields. These requirements include multi-channel operation in a dense package, high reliability, sufficiently fast operation, and inexpensive fabrication techniques.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an apparatus for at least partially intercepting a plurality of light beams propagating along a respective plurality of beam paths comprises a single crystal silicon substrate comprising a substrate surface with a surface normal direction. The apparatus further comprises an array comprising a plurality of modules. Each of the modules comprises a reflector comprising single crystal silicon and a reflector surface lying in a reflector plane substantially perpendicular to the substrate surface. Each module further comprises a reflector support which mounts the reflector to move substantially within the reflector plane with a displacement component along the surface normal direction of the substrate surface. Each module further comprises a reflector driver responsive to electrical current to selectively move the reflector between a first position in which the reflector intercepts at least a portion of one of the beam paths and a second position in which the reflector does not intercept the portion of one of the beam paths. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases, whereby the movement of the reflectors is individually addressable.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively move the reflector along a curved path lying substantially in the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when electrical current flows therethrough and moves to the second position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver which receives and is responsive to an electrical signal to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the first position when the electrical signal is received and moves to the second position when the electrical signal is not received.
According to another aspect of the present invention, a module for at least partially intercepting a light beam propagating along a beam path comprises a reflector comprising single crystal silicon, with the reflector lying substantially in a reflector plane. The module further comprises a reflector support which mounts the reflector. The module further comprises a reflector driver responsive to electrical current to selectively rotate the reflector about an axis substantially perpendicular to the reflector plane. The reflector is movable between a first position in which the reflector intercepts at least a portion of the beam path and a second position in which the reflector does not intercept the portion of the beam path. At least a portion of the reflector driver is mounted to the reflector support and is conductive to electrical current, such that the reflector moves to the second position when electrical current flows therethrough and moves to the first position when electrical current flow ceases.
According to another aspect of the present invention, a module for at least partially intercepting
Avakian Aramais
Chiu Chen-Wei
Dickson Jeff
Jiang Fukang
Tai Yu-Chong
Ben Loha
Choi William
Knobbe Martens Olson & Bear LLP
Umachines, Inc.
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