Optical waveguides – With optical coupler – Switch
Reexamination Certificate
2001-09-27
2003-10-28
Lee, John D. (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S018000, C385S016000
Reexamination Certificate
active
06640023
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of optical switches, and more particularly to reflective-type optical switches for switching optical signals between any pair of optical ports to/from the switch interface.
BACKGROUND OF THE INVENTION
With the increasing use of optical signals in telecommunications networks, the demand for high-bandwidth capable optical switches that can quickly route the optical signals along desired optical paths has increased. One type of optical switch converts an optical signal received on one optical port (e.g., an optical fiber end) to the switch interface to an electrical signal, switches the signal electronically, and re-converts the electrical signal to an optical signal output on a desired optical port (e.g., another optical fiber end) from the switch interface. Such optical switches are known as Optical Electrical Optical (OEO) switches. As may be appreciated, the bandwidth and switching speed capabilities of an OEO switch may be limited by the initial optical-to-electrical and subsequent electrical-to-optical signal conversions that are required.
A different approach to the switching of optical signals is known that overcomes the limitations of OEOs by switching the signals in the optical domain eliminating the optical-to-electrical and electrical-to-optical signal conversions. Such all optical switches are known in the art as Optical Cross Connect (OXC) switches. One type of OXC utilizes moveable reflectors (e.g., mirrors) to provide for the switching of optical signals within the free-space of the switch interface (i.e. without optical fibers, waveguides or the like). Typically such switches employ at least a pair of reflectors that are moved to respective orientations in order to provide an optical pathway within the free-space of the switch interface between any one of a plurality of input ports to the switch interface and any one of a plurality of output ports from the switch interface. As may be appreciated, an important parameter of such reflective-type free-space OXCs is the length of the path that an optical signal must traverse in order pass from one of the input ports to one of the output ports. Another parameter of importance to such reflective-type free space OXCs includes the proximity of the optical inputs and outputs to the reflectors, because as the distance between the reflectors and the inputs and outputs increases, there is less tolerance to alignment inaccuracies between the reflectors and the inputs and outputs.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a free-space optical cross connect for switching optical signals between optical signal ports to/from the switch interface. The optical cross connect of the present invention provides a compact switch wherein all of the moveable reflectors are supported on a single substrate. Having all of the reflectors supported on a single substrate provides for a minimal optical path length between a given pair of optical ports, and also permits the optical ports to be located in very close proximity to the reflectors. Having all of the reflectors on a single substrate also achieves advantages in the complexity of switch construction as it is not required that multiple substrates be properly oriented within the switch interface.
According to one aspect of the present invention, an optical cross connect for switching optical signals between a plurality of optical ports includes a substrate having a first surface facing the optical ports. A plurality of reflective microstructures are formed on the first surface of the substrate. Each reflective microstructure includes an optically reflective surface and is associated with one of the optical ports. Each reflective microstructure is positionable to orient its reflective surface to reflect an optical signal receivable from its associated optical port to the reflective surface of at least one other reflective microstructure. Each reflective microstructure is also positionable to orient its reflective surface to reflect an optical signal receivable from at least one other reflective microstructure to its associated optical port.
By properly orienting any pair of reflective microstructures on the substrate, an optical signal can be switched from any optical port to any other optical port. In this regard, the optical cross connect may further include a plurality of positioning systems formed on the substrate. Each positioning system is associated with one of the reflective microstructures and is operable to both elevate its associated reflective microstructure from the first surface of the substrate and tilt its associated reflective microstructure with respect to the first surface of the substrate with at least two degrees of freedom (e.g., about two substantially orthogonal axes). The reflective microstructures and their associated positioning systems may be respectively arranged and configured such that centers of the reflective surfaces of the reflective microstructures are aligned with central axes of their associated optical ports when the reflective microstructures are elevated at a specified height from the first surface of said substrate. This initial alignment helps maintain alignment of the optical signal beams with the reflective surfaces of the reflective microstructures as the reflective microstructures are tilted to redirect the optical signals since tilting of the reflective microstructures may result in small lateral movements of the centers of the reflective microstructures. Further, although many configurations are possible, the reflective surfaces of the reflective microstructures may, for example, be circular or elliptical in area. Employing elliptical reflective surfaces may provide for greater efficiency in the amount of optical energy that is reflected for the footprint area consumed by the reflective microstructures. This is because a typical telecommunications optical signal beam is circular in cross-section and thus has an elliptically shaped intersection with a flat surface intersecting the beam at an angle thereto.
If desired (e.g., to protect the surface of the substrate and the reflective microstructures and positioning systems formed thereon), the optical cross connect may further include a lid positionable between the optical ports and the first surface of the substrate. The lid may be hermetically sealed with the substrate to prevent the entry of contaminants into the switch interface. The lid is configured to permit transmission of optical signals therethrough between each optical port and its associated reflective microstructure. For example, the portions of the lid between the optical ports and the reflective microstructures may be made of an optically clear material.
The optical ports may comprise optical fiber ends that abut a side of the lid that faces away from the first surface of the substrate. In this regard, the lid may also facilitate alignment of the optical fiber ends with their associated reflective microstructures. For example, there may be a plurality of holes within which the optical fiber ends are receivable formed on the side of the lid facing away from the first surface of the substrate. The fiber end receiving holes can be arranged on the lid in a pattern appropriate to align the optical fiber ends with the reflective microstructures when the reflective microstructures are in a predetermined position (e.g., when the reflective microstructures are elevated at a specified height from the first surface of the substrate). Alternatively, the optical cross connect may further include one or more plates that are attachable to the lid. The plate(s) include a plurality of holes within which the optical fiber ends are receivable. The fiber end receiving holes in the plate(s) are arranged in a pattern appropriate to align the optical fiber ends with the reflective microstructures when the plate(s) are attached on the lid. Pins, grooves, notches or the like may be employed to ensure proper positioning of the plates when attaching the pl
Barnes Stephen Matthew
McWhorter Paul Jackson
Miller Samuel Lee
Rodgers Murray Steven
Sniegowski Jeffry Joseph
Lee John D.
Marsh & Fischmann & Breyfogle LLP
Memx, Inc.
Valencia Daniel
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