Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2000-10-16
2001-07-24
Ben, Loha (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S291000, C359S619000, C359S237000, C359S246000, C359S247000, C359S320000, C385S016000, C385S018000, C385S042000
Reexamination Certificate
active
06266176
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is in the field of optical interconnection devices, such as those that may be useful in routing information for communications systems.
BACKGROUND OF THE INVENTION
This invention relates to apparatus supporting optical interconnection, such as those that may be useful in the routing of signals in the communications industry. In communications systems such as telecommunications systems, optical signals currently must be downconverted to an electrical signal before being transmitted over long distances. The transmission rate of these electrical signals is much slower than that of optical signals. This conversion is a barrier to a fast Internet system capable of delivering applications requiring significant bandwidth, such as streaming on-demand video and music. It is therefore desirable to use a system that keeps signals in their optical form without having to convert to a slower, less-efficient electrical system.
One area to be addressed is the electronic switches in fiber-optic backbones. Backbones are expensive communications links between major cities. Optical fibers often carry information to central hubs in these major cities, then creating a bottleneck at each hub while all this information waits to be converted into electrons and switched by bulky electronic switches. This conversion process was sufficient when fiber optics carried only one signal over a limited distance, but electronics now have difficulty keeping up with the newly complex signals.
The industry has turned its attention toward photonic switches. Photonic switches do not require signal downconversion, and are capable of optically directing even complex light streams. Several variations of these photonic switches have been reported. Agilent reportedly uses bubbles to deflect light between crisscrossing glass columns in order to direct light back and forth to the switches. Corning is reportedly investigating liquid crystals to redirect the light streams. Bell Labs is reportedly using tiny micromirrors to direct beams to the appropriate fibers. While these systems are much smaller than the previous switching systems, and may effectively achieve the desired optical switching, they can be very complex. For example, in the Bell Labs device where an array of micromirrors is used to direct beams to the appropriate fiber, each mirror must be accurately calibrated to send a beam to any of the appropriate fibers. The calibration must also take into account any minute variation in position from fiber to fiber, an array of fibers not being aligned in perfect rows and columns.
It is therefore an object of the current invention to create a photonic switching device that is compact in design, relatively simple to setup and operate, and can effectively route multiple complex light streams.
Although described with respect to the field of communications, it will be appreciated that similar advantages of optical routing, as well as other advantages, may obtain in other applications of the present invention. Such advantages may become apparent to one of ordinary skill in the art in light of the present disclosure or through practice of the invention.
SUMMARY OF THE INVENTION
The present invention includes optical interconnection devices and optical interconnection systems. The invention also includes machines and instruments using those aspects of the invention. The invention may also be used to upgrade, repair, or retrofit existing machines or instruments, using methods and components known in the art.
The present invention includes an optical interconnection device utilizing a multiple-pass optical cell and at least one spatial light modulator. In a spatial light modulator, each individual element typically only has two or three variations used to direct the light. In an optical configuration of the present invention, such as a White cell, precise calibration of each individual element is not needed. The light simply needs to be directed toward the appropriate arm of the optical cell, which utilizes a self-correcting mirror in order to direct a light stream to the next desired location in the system.
An optical interconnection apparatus included in the present invention utilizes at least one input light source to generate an array of light beams. A light beam may be of any appropriate wavelength, and it should be understood that an input signal may also comprise any appropriate beam that can carry information and be directed by the elements of the present system. An input mirror may be used to reflect this array to an optical configuration, such as a White cell or equivalent optical device or array, comprising a plurality of optical elements such as mirrors, lenses, gratings, and prisms. These elements are configured so as to define multiple possible light paths for each light beam in the array. At least one refocusing optical element preferably restricts the divergence of a light beam diverted by the optical elements through at least one of the light paths. A spatial light modulator selects a path from among the light paths for each pass of a light beam through the optical elements. Each beam will undergo multiple reflections off the spatial light modulator. An output plane then receives each light beam emerging from the optical elements. The output plane preferably has two dimensions. The resultant position of each light beam on the output plane is determined in part by the position of the light beam in the input array. The particular light paths traveled by the beam through the optical elements also determine the output location. The emerging light beams may also be placed across a non-planar array to form a non-planar pattern, and the position determined accordingly (although this may make positional determination more difficult).
In another apparatus for optical interconnection included in the present invention, at least one input light source generates at least one individual light beam from at least one direction. An input mirror preferably reflects the beam(s) to a first optical configuration, such as a first White cell or equivalent optical device or array. The first optical configuration is made up of a first plurality of optical elements configured so as to define a plurality of possible light paths for each light beam, and a first spatial light modulator adapted to select a path for each pass of a light beam through the first plurality of optical elements.
The apparatus also utilizes a second optical configuration, such as a second White cell or equivalent. The second optical configuration receives as input any light beams emerging from the first optical configuration. The second optical configuration is made up of a second plurality of optical elements configured so as to define a plurality of possible light paths for each light beam emerging from the first optical configuration, and a second spatial light modulator adapted to select a path from among the light paths for each pass of a light beam through the second plurality of optical elements. The apparatus preferably utilizes an output mirror to reflect each light beam emerging from the second optical configuration. At least one receiving device then receives any emerging light beam. The first and second optical configurations are configured such that a similar period of time is needed for each light beam to pass from the input light source through the optical configurations to the receiving device. The first and second pluralities of optical elements preferably comprise mirrors, lenses, gratings, quarter wave plates, and prisms.
Alternatively, the first and second spatial light modulators may be replaced by a single spatial light modulator. The spatial light modulator is then shared by the two optical configurations, preferably having a portion dedicated to each. The pluralities of optical elements have to be arranged accordingly.
The present invention also includes an optical switching apparatus. The apparatus has as an input source at least one input optical fiber, each input optical fiber adapted to
Anderson Betty Lise
Collins Stuart A.
Ben Loha
Standley & Gilcrest LLP
The Ohio State University
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