Disk drive optical switch

Details Disk drive optical switch Disk drive optical switch

2000-07-26

2004-01-13

Ullah, Akm Enayet (Department: 2874)

Optical waveguides

With optical coupler

Switch

Reexamination Certificate

active

06678434

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to optical switches, particularly to the use of voice coil motor based computer disk drive assembly technology to align input and output optical channels.
2. Background Art
Present day optical fiber technologies are revolutionizing the telecommunications industry. Tremendous advances have been made in the field of telecommunications over the past decade. It has been estimated that this technology is capable of carrying tens of millions of conversations simultaneously on a single optical fiber. Optical fiber communication systems offer many advantages over systems that use copper wire or radio frequency links as transmission media. They include lower transmission losses, higher bandwidths, higher transmission rates, lower implementation costs, greater reliability and greater electrical isolation characteristics. It is clear that optical fiber communication will dominate the telecommunications industry in the very near future because of advantages such as these.
Fiber optic switching is an important component in any telecommunication system. These systems use switches to establish communication channels among two or more of their interfaces. An optical fiber switch is capable of optically connecting, interrupting or aligning, any one or more of a first group of optical fibers with any one or more of a second group of optical fibers, or vice versa, enabling an optical signal to propagate through the optical interface junction between newly aligned fibers.
When two optical fibers are aligned end-to-end, light entering one fiber (the input or sending fiber) will continue into and through the second fiber (the output or receiving fiber) while the two adjacent ends, or faces, are aligned and close together. Fiber optic switches misalign or disjoin the adjacent ends of the fibers by moving one or both of the two ends. By moving, for example, the first fiber's end to a new location, the signal, in this case light, can be redirected into a third fiber by aligning the first fiber's end with an end of the third fiber.
Lateral separation of two adjacent fiber ends will result in loss of light between the two fibers and a light absorber is typically provided beside the fiber which either moves into place as the receiving fiber moves away or stays in place as the sending fiber moves away. Space is provided for this motion. This effectively switches the signal off. The discontinuity between the fiber ends may be either perpendicular to the fiber axis or at some angle to the axis but the gap is minimal when the fibers are aligned.
Fibers are often collected into a bundle, a fiber optic cable, with a structure set up at the active location to permit the required motion of a fiber end. A fiber bundle can be separated from a circular bundle cross-section to a linear arrangement where the fibers are in a straight line at the switch but reformed into a bundle again at the device exit.
Optical fiber switches may include electronic processing as part of signal transmission. Switches wherein the signal is entirely optical while being transmitted, such as the present invention, are described as photonic. Optical fiber switches, which are totally photonic, generally utilize fiber positioning means, alignment signal emitter means and computer control means. Some switching concepts, not utilized in the present invention, may include light beams and lenses. Normally, a fiber positioning means is provided near the end of one fiber to selectively point the end of that fiber in one fiber group toward the end of another fiber in the other fiber group to perform a switched optical transmission. Patents proposing to perform such switching actions in fiber optic telecommunication systems include: U.S. Pat. No. 5,024,497, to Jebens, entitled “Shape Memory Alloy Optical Fiber Switch,” which discusses switching activated by a shape memory alloy wire in a transverse direction. U.S. Pat. No. 4,512,036, entitled “Piezoelectric Apparatus for Positioning Optical Fibers,” U.S. Pat. No. 4,543,663, entitled “Piezoelectric Apparatus for Positioning Optical Fibers,” U.S. Pat. No. 4,651,343, entitled “Piezoelectric Apparatus for Positioning Optical Fibers,” and U.S. Pat. No. 5,524,153, entitled “Optical Fiber Switching System and Method Using Same,” all to Laor, use piezoelectric bimorphs for positioning optical fiber switches. U.S. Pat. No. 4,303,302, to Ramsey, et al., entitled “Piezoelectric Optical Switch” discusses other forms of piezoelectric bimorphs for optical fiber switching.
Other patents discussing fiber optic switching include: U.S. Pat. No. 5,812,711, to Glass, et al., entitled “Magnetostrictively Tunable Optical Fiber Gratings”; U.S. Pat. No. 5,812,711 to Malcolm, et al., entitled “Magnetostrictive Tunable Optical-Fiber Gratings”; U.S. Pat. No. 4,759,597, to Lamonde, entitled “Mechanical Switch for Optical Fibers”; U.S. Pat. No. 4,415,228, to Stanley, entitled “Optical Fiber Switch Apparatus”; U.S. Pat. No. 5,004,318, to Ohashi, entitled “Small Optical Fiber Switch”; U.S. Pat. No. 4,844,577, to Ninnis, et al, entitled “Bimorph Electro Optic Light Modulator”; U.S. Pat. No. 4,512,627, to Archer, et al., entitled “Optical Fiber Switch, Electromagnetic Actuating Apparatus with Permanent Magnet Latch Control”; U.S. Pat. No. 5,699,463, to Yang, et al., entitled “Mechanical Fiber Optic Switch”; U.S. Pat. No. 5,841,912, to Mueller-Fiedler, entitled “Optical Switching Device”; U.S. Pat. No. 5,647,033, to Laughlin entitled “Apparatus for Switching Optical Signals and Method of Operation”; U.S. Pat. No. 4,886,335, to Yanagawa, et al., entitled “Optical Fiber Switch System”; and U.S. Pat. No. 4,223,987, to Kummer, et al., entitled “Mechanical Optical Fiber Switching Device.” These patents disclose various methods for fiber optic switching, including mechanical devices such as rods, motors, and adapters, as well as wave guides and reflectors.
The present invention overcomes deficiencies in the prior art and provides fast and accurate optical switching. A modified conventional computer disk drive is used to move optical fibers over distances of a few centimeters with an access time of a few milliseconds. A group of fibers are input through and held by the actuator arm, or head, assembly of the computer disk drive and movement of the actuator arm then aligns/misaligns the input fibers with selected output fibers that are placed through and held by the disk of the disk drive. Additionally the disk is partially rotatable, and the combined movement of the actuator arm and the disk increases the switching speed. A conventional computer disk drive with a high resolution voice coil motor is used to achieve positional resolution on the order of 0.5 micron.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
The present invention is an optical switch comprising at least one actuator arm for fixedly holding at least one input optical channel, and a disk for fixedly holding at least one output optical channel, wherein at least one of the actuator arm and disk are movable with respect to the others so that the at least one input optical channel is aligned with selected of the at least one output optical channel. The actuator arm comprises at least one opening for fixedly holding at least one output end of the at least one input optical channels. The disk also comprises at least one opening for fixedly holding at least one input end of the at least one output optical channel.
A voice coil motor is used for receiving a switching signal to cause each actuator arm to move with respect to the disk. The voice coil motor can be a linear voice coil motor if the actuator arm is a linear actuator arm. Otherwise the actuator arm is pivotable. Preferably the voice coil motor comprises a high resolution voice coil motor providing a positional resolution of between approximately 0.25 and 1 micron. The optical switch further comprises fixed supports for stabilizing the input and output optical channels. The disk of the optical switch pref

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