WO1992020002A1

WO1992020002A1 - Ruggedized bypass switch

Info

Publication number: WO1992020002A1
Application number: PCT/US1992/003461
Authority: WO
Inventors: William David Uken; Thomas D. Ratzlaff; John B. Stewart, Jr.; Marc C. Cohn
Original assignee: Raychem Corporation
Priority date: 1991-04-26
Filing date: 1992-04-27
Publication date: 1992-11-12
Also published as: EP0581884A1; JPH06507504A

Abstract

A ruggedized optical bypass switch includes a refractive member which has first and second positions for establishing a normal switch state and a bypass switch state. Since a path length of signals coupled to a network fiber through the refractive member is constant regardless of its position, effective focusing can be effectively achieved by use of only a single lens, the lens being either reflective or refractive. The refractive member is rotatable about its center of gravity between its first and second switching positions making it largely insensitive to shock and vibrations loads.

Description

Ruggedized Bypass Switch

This application is a continuation-in-part of pending U.S. patent application no. 07/692,102 filed April 26, 1991, entitled "Ruggedized Bypass Switch", assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference.

The present invention relates to an optical switch, a preferred use being for use in optical networks having a need for bypass switches.

Numerous optical switches have been proposed in the prior art. One such switch is disclosed by Fujita et al. USP 4,893,891, who proposes disposing a glass plate or glass prism between optical elements, and rotating the glass plate or glass prism about an angle approximately 45° to achieve optical switching between pairs of optical elements. These switches suffer from numerous disadvantages. One such disadvantage is that the amount of rotation required to achieve the desired switching effect is unduly large which lengthens an amount of time it takes to achieve switching operations. More importantly, since a path length of a signal passing through the glass plate or glass prism changes between an unswitched and switched state of the optical switch, an optical path length of the signal also changes which prevents optimum focusing to be prearranged by precise placement of various ones of the optical elements without ext^ sive use of leases. Accordingly, this reference teaches using a plurality of lenses which create collimated light beams which accordingly are inherently unaffected by changes in distances the signals must pass through the glass plate or glass prism. The numerous lenses so required complicate construction of the device as well as its cost.

Stanley USP 4,854,659 discloses a manner of switching signals by deflecting a cantilevered vertically hinged silicon beam which reflects signals from a surface thereof. A disadvantage of such cantilevered pivoted designs is that they are severely adversely affected by vibrational loads. Reedy USP 4,705,349 discloses an optical switch whereby signals between optical elements are switched by revolving a mirror between first and second positions. Again, such switching devices are complicated in design and also are adversely affected by mechanical vibrations since an apparatus holding the mirror is relatively heavy and since only a relatively small angular motion is required to move the switch from state to state. The heavy weight of the component gives it a rather large inertial component when subjected to shocks, and the tiny motion necessary for switching render the device extremely sensitive to both shock and vibration loads.

Various other methods and devices have been proposed in the prior art for optically switching signals, and these too suffer various disadvantages related to complexity of design as well as stability of operation.

Accordingly, it is an object of the present invention to provide an optical switch which is inherently stable during shock and vibration loads.

It is a further object of the invention to provide an optical switch which is compact in size, requires relatively little power to operate, is flexibly mountable, and utilizes fixed fibers and focusing elements.

It is yet a further object of the invention to provide an optical switch which does not require the use of an unduly large number of focusing elements.

These and other objects of the invention are achieved by an optical switch, comprising:

at least first, second, and third optical elements; refractive means disposed along a light path which can optically connect the second element with the first element when the refractive means is in a first position, and can optically connect the third element with the first element when the refractive means is in a second position;

means for rotating the refractive means between the first and second positions for switching an optical connection between the first and second element and the first and third element, a first distance a first optical signal travels through the refractive means when the second element is optically connected to the first element when the refractive means is in its first position being substantially the same as a second distance a second optical signal travels through the refractive means when the third element is optically connected to the first element when the refractive means is in its second position;

the refractive means being rotated about its center of gravity.

The invention further includes an optical switch which comprises means for rotating the refractive means between the first and second positions for switching an optical connection between the first and second element and the first and third element, a first angle a first optical signal makes with a normal to a surface of the refractive means through which the first optical signal travels as it passes through the refractive means when the refractive means is in its first position being substantially the same as a second angle a second optical signal makes with a normal to a surface of the refractive means through which the second signal travels as it passes through the refractive means when _ _- refractive means is in its second position.

Preferably the rotation means is rotatable through an angle less than 30° between its first and second positions. Also, the invention includes an optical switch apparatus, comprising first and second optical switches, each switch comprising:

at least first, second, and third optical elements;

refractive means disposed along a light path which can optically connect the second element with the first element when the refractive means is in a first position, and can optically connect the third element with the first element when the refractive means is in a second position;

means for rotating the refractive means between the first and second positions for switching an optical connection between the first and second element and the first and third element,

the third element of the first switch and the first element of the second switch comprising a common optical fiber having no splices or optical connectors along a length thereof between its first and second opposite ends, and further comprising means for securing the first fiber end within the first switch, and means for securing the second fiber end within the second switch.

The invention will be better understood by reference to the following drawings and detailed description.

FIG 1 illustrates a block schematic of a bypass switch in its normal state;

FIG 2 illustrates a block schematic of a bypass switch in its bypass state;

FIGs 3 A and 3B illustrate one preferred embodiment of the invention, FIG 3A illustrating an optical switch in its normal state, and FIG 3B illustrating this switch in its bypass state; ε

FIGs 4A and 4B illustrate a second embodiment of the invention which utilizes one focusing element, FIG 4A illustrating a normal state of the switch and FIG 4B illustrating a normal state of the switch;

FIG 5A illustrates one preferred embodiment of the invention conceptually illustrated in FIG 4A;

FIG 5B illustrates a plan view of a mechanism for stopping a rotor in the device of FIG 5B between first and second positions;

FIG 5C is a cross sectional view of the rotor and magnetic armatures illustrated in FIG 5A in a switch bypass state;

FIG 5D illustrates a position of the rotor and armature in the switch normal state;

FIG 5E illustrates an alternate rotor-armature arrangement;

FIG 6 illustrates a preferred fiber holder for the optical switch;

FIG 7 illustrates an alternate rotor-permanent magnet construction;

FIGs 8 A and 8B illustrate a preferred switch logical connection and apparatus for a plurality of in-line switches.

FIG 9 illustrates a user interface for the FIG 8A switch configuration.

FIG 1 illustrates a block schematic of a bypass switch 8. Referring to this figure, an optical fiber network 1 includes a transmission optical fiber 2, 12 which allows communication between a plurality of nodes 3, only one of which is illustrated in FIG 1. A logical and physical architecture of the network 1 is not particularly relevant to the invention, typical architectures being single ring, redundant ring, bus, etc. According to the network of FIG 1, a first signal illustrated by arrow 4 is received by node 3 from an incoming optical fiber 2 through switch 8 and detected by receiver 5, and a second signal 7 from the node 3 is generated by transmitter 6 and sent along the network 1 as illustrated by arrows 7 by being transmitted through the switch 8 and into an outgoing network optical fiber 12. In the event the node 3 fails for any reason, a danger exists that communication along the network 1 will be permanently disrupted, and accordingly it is desired to provision or construct the switch 8 so as to have both a "normal" state and a"bypass" state. FIG 1 illustrates the normal state whereby the first signal represented by the arrows 4 is switched to the node 3 and the second signal indicated by the arrows 7 is switched from the node 3 to the outgoing transmission fiber 12.

FIG 2 illustrates a bypass state of the switch 8 whereby the first signal 4 is transmitted from the incoming fiber 2 to the outgoing fiber 12 through the switch 8 so as to effectively bypass the node 3, this state being desired when the node 3 is inoperable or shut down for any reason. In addition, the node transmitter signal 7 is looped back to the node receiver 5 by the switch enabling the node to monitor operation of the node transmitter 6 and receiver 5.

FIGs 3A and 3B illustrate in conceptual form one preferred embodiment of the switch 8. Referring to FIG 3A which illustrates a normal state of the switch, the first signal 4 comes into the switch from the left along the incoming fiber 2, is focused by lens 14 into a refractive member 15 so as to be detected by the node receiver 5. Node transmitter 6 then generates the second signal 7, shown again at the left portion of FIG 3 A, and the second signal is again refracted by the lens 14 into the refractive member 15 so as to be retransmitted onto the transmission optical fiber 12.

In the event the node 3 were to fail or become inoperative, the switch 8 switches to its bypass state, illustrated in FIG 3B, by rotating the refractive member 15, preferably about its center of gravity 16. Rotation about the center of gravity minimizes adverse effects from shock and vibration loads.

Preferably, first and second rotational positions of the refractive member 15 defining the normal and bypass states illustrated in FIGs 3 A and 3B are symmetrically arranged such that the outgoing fiber 12 always receives a focused signal even in instances where collimated beams are not transported through the switch. More specifically, optimally the first and second positions of the refractive element are such that a distance the signal 7 travels through the refractive member 15 when the switch is in the normal state (FIG 3 A) substantially eqaals a distance the signal 4 travels through the refractive member 15 when the switch is in its bypass state (FIB 3B). Accordingly it can be appreciated that by optimally choosing a focusing profile of the lens 14 and the output locations and beam divergent characteristics of the transmitter means 6 (e.g. commonly an output of a fiber connected to the transmitter) and the transmission fiber 2, the single lens 14 can readily optimally focus both the signal 7 in the normal state and the signal 4 in the bypass state onto an end of the outgoing fiber 12 since a distance of travel of the signals through the refractive member does not vary. By contrast, in the switch of Fujita et al., USP 4,893,891, cited above, since a distance of signal travel through their refractive element varies, collimated beams are required to achieve respectable focusing in the outgoing fiber in both a normal and bypass state. Accordingly, as used herein, when reference is made to distances of travel of optical signals through the refractive member 15 being "substantially the same", it is intended that the distances be identical within a tolerance that results in effective focusing of both the signal 4 and the signal 7 into the output optical fiber such that an attenuation difference between losses incurred due to any difference in focusing of the signal 4 and the signal 7 into the outgoing transmission fiber 12 does not exceed 0.7 dB, preferably does not exceed 0.5 dB, more preferably does not exceed 0.4 dB, even more preferably does not exceed 0.3 dB. Obviously, surface irregularities and ciystallinity differences within the refractive member 15 will cause some minute difference between a path length of the signal 4 and the signal 7 through the refractive means when each signal is respectively being focused onto the outgoing transmission fiber 12, and accordingly minute differences between these distances when these signals are being refracted into the outgoing transmission fiber 12 are included within the scope of the invention.

Also, preferably the first and second positions of the refractive member 15 are such that, when the switch is in its normal state, a first angle the signal 7 makes with a normal line 37, which is normal to a point on the refractive member surface where the first signal enters the refractive member surface as it goes from the node transmitter 6 to the outgoing optical fiber 12, is substantially equal to a second angle the signal 4 makes with the normal 37 as the signal 4 passes through refractive member 15 to the outgoing transmission fiber 12. Again, the phrase "substantially the same" includes small tolerances or small differences so long as they do not result in appreciable differences in focusing powers or focusing efficiencies between the signal 4 and the signal 7 as it impinges on an opening or end of the outgoing transmission fiber 12 according to the efficiencies, denoted in decimals, cited immediately above.

Referring back to the bypass state of FIG 3B, the first signal 4 is coupled directly through the lens 14 and refractive member 15 into the output of the outgoing transmission optical fiber 12 so as to bypass both the node receiver 5 and node transmitter 6. In addition, in the bypass state, the second signal 7 generated by the node transmitter 6 is coupled by the lens 14 and refractive member 15 into a loop back member 17, preferably a waveguide, e.g. an optical fiber, which is arranged so as to loop the second signal 7 back around again through the lens 14 and refractive member 15 so as to be received by the receiver 5. Accordingly, by coupling logic to an output of the receiver 5, the node 3 is able to determine its own state of operation and accordingly can provide a warning when it is not operating properly so as to prevent the switch 8 from returning to its normal mode, and alternatively can indicate when it is operating properly and the switch 8 can safely be switched to its normal state.

According to the embodiment of FIG 3, only one focusing element or lens 14 is required, and this element can be used to focus what is otherwise a diverging signal 4 emitted from the transmission fiber 2 into a converging signal which will be appropriately focused at either the node receiver 5 (normal state) or an end of the outgoing transmission optical fiber 12 (bypass state). In addition, as previously explained, in the normal state of operation of the switch 8, the transmitter 6, lens 14, and refractive member 15 can be easily located so as to optimally focus the signal 7, to be transported on the network, onto an end of the outgoing optical fiber 12. Accordingly, in the normal state, optimum power is supplied to the outgoing fiber 12, and optimum power is coupled into and received by the receiver 5 in this state thereby optimizing performance of the node 3. Furthermore, in the bypass state, optimum power is coupled between the incoming fiber 2 and the outgoing fiber 12 when the signal 4 is simply bypassing the node 3. In addition, optimum power is coupled between the node transmitter 6 and the loop back fiber 17. Since at an output of the loop back fiber the signal 7 is diverging in much the same manner as does the signal 4 from the fiber 2, the signal 7 is then optimally coupled to the node receiver 5.

FIGs 4A and 4B illustrate an alternate embodiment of the invention, these figures illustrating another switch 18 which utilizes a focusing reflective element or lens 24, e.g. curved mirror, in place of the refractive lens 14 shown in FIG 3. Referring to FIG 4 A which illustrates the switch 18 in its normal state, a first signal 4 coming into the switch from the end of the incoming transmission fiber 2 is refracted through the refractive member 15 towards the focusing refractive mirror 24 back through the reflective member 15 so as to be detected by the node receiver 5. Similarly, a second signal 7 generated by the node transmitter 6 is refracted through the refractive member 15 towards the reflective focusing mirror 24 which reflects the signal 7 /-> back through the refractive member 15 and out on the outgoing transmission optical fiber 12, as illustrated.

In the event the node 3 fails, the switch 18 is switched to its bypass state by rotating the refractive member 15, again optimally about its center of gravity 16, by an amount such that a total distance traveled by the first signal 4 through the refractive member 15 in the FIG 4 A state remains substantially the same as the distance the second signal 7 travels through the refractive member in the FIG 4B state. Thus these distances are independent of the position of the reflective member 15. Accordingly, optimum focusing of the signal 4, which comes into the switch 18 from the transmission optical fiber 2, is optimally focused on the outgoing transmission optical fiber 12. As FIG 4B illustrates, in the bypass state, though the first signal 4 effectively bypasses the node transmitter and receiver 6, 5, and is coupled to the outgoing fiber 12, the second signal 7 generated by the transmitter 7 is refracted through the refractive member 15 onto the reflective focusing mirror 24 so as to be reflected back through the refractive member 15 onto a loop back waveguide 17 which sends the second signal 7, now denoted as signal arrow (7) T back through the reflective member 15 again off the reflective lens 24 so as to pass through the refractive member 15 a fourth time and be received by the node receiver 5. Accordingly, again the node 3 has the ability to determine when its optical transmitter and receiver are both working properly or improperly so as to increase reliability.

According to the invention, locations of the transmitter 6 and outgoing transmission fiber 12 are optimally located in conjunction with a focusing power of the lens 14 and a position of the refractive member 13 so as to achieve optimal coupling between the transmitter 6 and the outgoing fiber 12 when the switch is in its normal state. Likewise, locations of the receiver 5 and the incoming fiber 2 are optimally located in conjunction with the focusing power of the lens 14 and a position of the refractive member 13 so as to achieve optical coupling between the receiver 5 and the incoming fiber 2 when the switch is in its normal state. Hence, it will be appreciated that since a path length of the signal 4 through the refractive member 15 when th switch is in its bypass state is substantially the same as a path length of the signal 7 through the refractive member 15 when the switch is in its normal state, optimum focusing between the incoming and outgoing fibers 2, 12 is automatically achieved when the switch is in its bypass state. Accordingly, optimum focusing between all the optical elements utilized in the invention is achievable with only the use of a single lens 14 (or lens 24 in the FIG 4 embodiment). A location of the end or output of the incoming transmission fiber 2 is positioned so as to achieve optimal coupling between the fiber 2 and the fiber 12 when the switch 8 is in the bypass state, and between the fiber 2 and receiver 5 in the normal state.

FIG 5A illustrates one preferred construction of a device incorporating the conceptual elements illustrated in FIGs 4 A and 4B. Referring to FIG 5 A, the switch 18 includes the refractive member 15, illustrated as a cylindrical glass member, embedded within and attached to a cylindrical rotor 21 having a cylindrical axis essentially perpendicular to a cylindrical axis of the refractive member 15. The rotor 21 is rotatable about its cylindrical axis by forces generated between a permanent magnet 22 having first and second ends 23 which are adjacent to and closely confront first and second electromagnetic armatures 34 which in turn are magnetically connected to first and second electromagnets 25. The electromagnets 25 are magnetically interconnected by an appropriate ferromagnetic material 26, with the electromagnets 25 being powered by electricity provided by electrical coils 26. As can be appreciated, the electromagnets 25, ferromagnetic material 26, armatures 34, and permanent magnet 22 form a magnetic circuit whereby energization of the coils 26 along one polarity causes the permanent magnet 22 to attempt to align itself with ends of the armatures 34, and an opposite electrical polarity provided by the electric coils 27 causes the ends of the permanent magnet 22 to be repelled away from the ends of the armatures 34 and hence deflect therefrom. By providing appropriate first and second stops 29, 30, illustrated in FIG 5B which are located so as to selectively engage first and second traverse edges 31, 32 on an outer circumferential surface of the rotor 21, positive first and second stop positions for the rotor can be established. According to the invention, preferably the first stop position is such that the cylindrical axis of the permanent magnet 22 is almost but not precisely colinear with a cylindrical axis of the armatures 34. Hence, a constant force is maintained against the first stop. Then, when the polarity of the electric coils 27 is reversed, since the ends of the electromagnets are reflected away from the corresponding ends of the permanent magnet, the repulsive force generated causes the armature to be stopped at the second position by the second stop 30.

FIG 5C illustrates a preferred construction of the ends of the permanent magnet 22 and the confronting ends of the electromagnetic armatures 34 in the bypass state, these ends preferably having a complementary shape, a preferred embodiment being convex and concave surfaces. Such a construction minimizes an air gap between the confronting ends of the armatures and the permanent magnet so as to decrease an amount of leakage of magnetic flux therebetween. FIG 5C illustrates a preferred position of the permanent magnet cylindrical axis relative to a cylindrical axis of the armatures 34, when the switch 18 is in its bypass state, e.g. its first stop position whereby the opposing ends of the permanent magnet and armatures are attracted so as to be short of being aligned so that a preferred rotational direction of the armature 21 will be induced when the repulsive magnetic force is generated by the electromagnets for achieving the second armature position (e.g. normal switch position).

FIG 5E illustrates another preferred construction of the electromagnetic armatures 34 and their orientation relative to the permanent magnet 22. According to this construction, ends of the armatures 34 are offset so as not to be in line as in the FIG 5C embodiment, and the armature ends confront opposite sides of the permanent magnet 22. FIG 5E illustrates one orientation of the magnet relative to the armatures when the switch is in one state, e.g. a normal state, whereby the armatures repel opposite ends of the permanent magnet, and when the switch is in the other state, i.e. the bypass state, a polarity of the armatures is reversed so that they attract the opposite ends of the permanent magnet and cause it to rotate in a counterclockwise direction by a desired amount, i.e. 8° for example in the counterclockwise direction as viewed in FIG 5E. This offsetting armature orientation has been found to be more efficient than the in-line configuration illustrated in FIG 5C, and accordingly less current is required for the switch.

The switch 18 further includes the reflective focusing lens 24 and a set of waveguides generically numbered as 40 which correspond to the input transmission optical fiber 2, the output transmission optical 12, a waveguide connected to the node receiver 5, a waveguide connected to the node transmitter 6, and first and second waveguides associated with the loop back waveguide member 17. Preferably ends of all these waveguides are coplanar and are fixedly secured to a fiber holder 62 by appropriate means, e.g. epoxy for example.

According to a preferred embodiment, the armature should be made of a material which is hard and light, titanium being more preferred than brass. A lightweight armature is desired so as to give the switch 18 superior stability when exposed to shock and/or vibration loads since the lighter the weight the lighter the inertial forces induced in shock and vibration. Also, if the rotor 21 and first and second stops 29, 30 are made of relatively hard materials, the switch can undergo numerous and repetitive switching operations without any significant "tunnelling" of the stops 29, 30 into the respective stop surfaces 31, 32 on the armature so as to minimize any variation of rotational range between the first and second stop positions over the useful life of the switch 18. According to a preferred embodiment, in addition to using as light a material as possible for forming the rotor 21, according to a preferred embodiment it is also advantageous to eliminate sections of the armature which are not required for its performance. Accordingly, a perfectly cylindrically shaped rotor 21 having only cutaway stop portions 31, 32 is disadvantageous as compared to an embodiment *4 whereby numerous sections of the armature have been cut away so as to decrease its mass. It can readily be appreciated by those skilled in the art that it could suffice to form the rotor 21 so as to have only a relatively small cylindrical outer surface along a section thereof which can form an appropriate bearing surface within the switch 18 for the rotor 21. It should also be appreciated that the bearing surface so formed by an outer circumferential section of the rotor 21 should preferably be sized so as to have a clearance with its complementary bearing cavity so that the outer circumferential surface of the rotor bears most if not all of the shock induced load whenever the rotor 21 is subjected to transverse loads along a direction transverse to its cylindrical axis. This minimizes shock loads on pin bearings 61 which are preferably disposed on first and second cylindrical ends of the rotor for providing normal bearing surfaces around which the rotor rotates. Accordingly, normal rotation of the rotor 21 is unimpeded by the cavity, with the cavity providing restraint and support to the rotor during extremely high g-load shocks enabling the rotor pin bearings to survive severe shock loading. This allows the switch to also survive such g-load shocks. Furthermore, preferably the rotor 21 is well statically balanced to render it insensitive to translational motion thus further stabilizing the switch during shock and vibration accelerations.

According to the construction just described, it will readily be appreciated that in the normal state of the switch 18, a signal 4 from an incoming transmission optical fiber 2 will be refracted through the refractive member 15 onto the reflective focusing lens 24 and back again through the refractive member 15 so as to be received by the node receiver 5 as schematically illustrated in FIG 4A. Likewise, a second signal 7 generated by the node transmitter 6 will be refracted through the refractive member 15, reflected and focused on member 24 back through the refractive member 15 so as to be focused onto an end of an outgoing transmission optical fiber 12. In the normal state, a current is supplied to the electromagnets 25 so as to create confronting like poles between the armatures 34 and the permanent magnet 22 so as to cause a repelling force therebetween. FIG 5D illustrates this state where the _ armature is in its first position. When the bypass state is desired, preferably current to the electromagnets 25 is zero with the armature 21 being positively rotated to its second position by forces generated by the permanent magnet 22 whereby the incoming signal 4 from the incoming transmission optical fiber 2 is directly routed through the refractive member 15, lens 24, refractive member 15, and focused onto an end of the outgoing transmission optical fiber 12 so as to bypass the node, with a second signal generated by the node transmitter 6 being looped back so as to be received by the node receiver 5 as described by reference to FIG 4B. FIG 5C illustrates this state and position of the armature.

Reference numeral 28 illustrates an optical fiber cable which includes the waveguides 40 held in holder 62. Fiber holder 62 is shown in detail in FIG 6, the holder comprising first and second blocks 63, 64 each having a plurality of semicylindrical apertures 65 therein, each pair of opposing semicylindrical apertures 65 forming a substantially cylindrical channel which contains an optical fiber secured therein. Preferably, a buffer of the optical fiber is stripped prior to inserting it into such a channel, and then the stripped fiber is secured within the channel using an appropriate securing means, such as an epoxy. The holder thus constructed positively secures and positions ends of the optical fibers 40 (e.g. reference numerals 2, 12, 17 and pigtails of receiver 5 and transmitter 6 by reference to FIG 4) so that switching using the refractive member 15 and the lens 24, as previously described, is accomplished. Also, preferably ends of the waveguides 40 have an antireflective coating disposed thereon.

According to the preferred embodiments described, since the refractive member 15 mounted in rotor 21 is rotated about its center of gravity, the stability of the switch 18 is greatly improved since it is largely insensitive to shock and vibration loads. In addition, the rotor 21, also being rotatable about a line along a center of gravity, is also largely insensitive to shock and vibrational loads as well thus further enhancing the stability of the switch 18. As the amount of refraction is controlled by the thickness and index of the refractive member 15, it can be appreciated that the amount of rotation required for switching can be modified by design and material changes. Switching speed is enhanced by smaller angular rotation, but the switch is less sensitive to angular errors and deviations during shock and vibration when larger angular rotations are employed. According to preferred embodiments, an amount of rotation for the refractive member 15 to switch between the first and second positions is less than 30°, preferably less than 25°, more preferably less than 20°, even more preferably less than 16°, optionally less than 12°, 10°, or 8°, but preferably between 4° and 16°.

FIG 7 illustrates an alternate preferred construction of the rotor 21 and the permanent magnet 22. In the FIG 7 embodiment, the permanent magnet 22' has an aperture 66 in a center portion thereof so that it can be assembled from an end of the rotor bearing 61 , as illustrated. This embodiment reduces the manufacturing complexity of the rotor 21' since a transverse cylindrical hole does not not need to be provided for the permanent magnet 22', as in the FIG 5A embodiment.

FIG 8 A illustrates a preferred coupling arrangement and architecture of multiple switches, and FIG 8B illustrates a preferred packaging embodiment of the multiple switches of FIG 8A whereby a plurality of the switches are disposed in line so that a plurality of pieces of telecommunications equipment can be connected thereto. Such a package arrangement is desirable where multiple pieces of telecommunications equipment to be connected to a network are located in close proximity to one another, e.g. in the case of a computer, associated printer, associated color monitor, etc. An advantage of the in-line packaging embodiment illustrated in FIG 8 is that a total number of external optical connections is reduced since no external connection(s) is(are) necessary for a signal leaving one switch and routed as an input directly into another switch. More specifically, an output of a first switch to be routed directly as an input to a second switch can be accomplished using a single optical fiber which has its opposite ends secured to its respective fiber holder 62 of the first and second switches. Since no optical splices or connectors are required for this connection, optical losses are less than that incurred when the switches are physically separated and the first switch output is connected to the second switch input using a transmission media which needs to be connected or spliced to fiber pigtails associated with the switches. In essence, the two switches share a common pigtail fiber, with one end of the pigtail fiber being secured in the first switch and the other end of the pigtail fiber being secured in the other switch.

A preferred architecture for the switches disclosed is for use in dual redundant counter rotating rings. Referring to FIG 8A, subscripts "p" represent a primary ring, and subscripts "s" represent a redundant dual counter rotating ring. During normal operation, primary ring p is utilized, and an incoming first signal at node Ap is transmitted in a normal switch state, through path 91 to port A 1-2 for reception by a receiver associated with a first piece of telecommunications equipment referred to as station 1. Software in station 1 then, instructs the station to transmit out of port B 1-4 to a further station, station 2, through path 94 and switch 18d. This signal is routed through switch 18d along path 91 ' to port A2-6 for use by another piece of telecommunications equipment referred to as station 2. Station 2 in turn transmits through port B2-8 for further transmission along the primary ring through node Bp along path 92'. In this case, according to preferred embodiments port B2-8 is connected to port A2-6 of the second station by path 94 when the switch 18d is in its bypass state, as previously explained. In the event of a failure at station 2, switch 18d could be switched from its normal to its bypass state so that the signal from port B 1-4 is transparently passed through the switch 18d to node Bp via switch path 93', also as previously explained. However, an alternative preferred embodiment is to simply bypass any connections to the station 2 altogether, this result being accomplished by station 1 via software control. Specifically, instead of station 1 transmitting out port Bl-4 toward station 2, station 1 instead transmits out port A 1-1 onto the secondary ring via node As through switch 18a. Signals are thus routed between multiple stations on the network using both the primary ring /S and the secondary ring, with a station 3, not shown immediately to the right of station 2, also doing a ring-to-ring transfer whereby signals which come into it from the secondary ring are routed back towards station 1 along the primary ring.

FIG 9 illustrates a preferred user interface for the embodiment illustrated in FIG 8A where first and second stations are to be connected to first and second redundant rings respectively, with the first and second stations being located in close proximity to each other such that they can be connected to a single patch panel. As FIG 9 illustrates, only a single power connection P is required, the one illustrated being that associated for switch 18a, with power being supplied to the other switches 18b-18d via power wiring internal to a housing which contains all four switches. As FIG 9 further illustrates, the switch 18a further has associated with it station receiver and transmitter connections R, T, and an incoming network connection (from the secondary ring) As; the second switch 18b has associated with it further station 1 receiver and transmitter connections R, T, and an incoming connection from the primary ring, Ap, with the third and fourth switches 18c, 18d each having receiver and transmitter connections R, T, for a station 2, with the switch 18c having an external connection for an outbound connection to the secondary ring Bs and the other switch 18d having an outboard connection to the primary ring Bp. "X"s indicate external network connections that are not required, since according to a preferred embodiment of the invention a signal outgoing from the port Bl-4 can be directly hard wire connected into the switch 18d. According to a preferred embodiment, this connection is done via a single optical fiber which has one end which terminates within the switch 18 at the fiber holder 62 (FIG 5A), with an opposite end of this fiber terminating in a similar fiber holder 62 in the switch 18d.

Accordingly, this connection requires no splices, mechanical connectors, or other type of internal connectors since there is no need for such.

As described, the switch of the invention provides a ruggedized bypass function which provides automatic focusing of a signal onto an outgoing transmission optical fiber with the use of minimum optical elements, the switch being largely insensitive to shock and vibrational loads, the switch including a simplified construction and requiring low power.

Though the invention has been described by reference to certain preferred embodiments thereof, it should be appreciated that various alterations and permutations thereof will be readily apparent to skilled artisans, and accordingly the invention should not be limited to only those specific preferred embodiments described and should only be limited by the appended claims.

Claims

1 -ZO

2 We claim:

3 i 1. An optical switch apparatus, comprising a first switch,

2 comprising:

3

4 at least first, second, and third optical elements;

5

6 refractive means disposed along a light path which can optically

7 connect the second element with the first element when the

8 refractive means is in a first position, and can optically connect

9 the third element with the first element when the refractive means 0 is in a second position; I 2 means for rotating the refractive means between the first and 3 second positions for switching an optical connection between the first and second element and the first and third element, a first 5 distance a first optical signal travels through the refractive means 6 when the second element is optically connected to the first 7 element when the refractive means is in its first position being 8 substantially the same as a second distance a second optical signal 9 travels through the refractive means when the third element is 0 optically connected to the first element when the refractive means 1 is in its second position; 2 3 the refractive means being rotated about its center of gravity. 4 i 2. The apparatus of claim 1, the signals being uncollimated as they

2 pass through the refractive means.

3 i 3. The apparatus of claim 2, the refractive means being rotated

2 through an angle less than 30° between its first and second positions.

3 4. The apparatus of claim 1, the first and second signals passing through the refractive means only once when the refractive means is in its first and second positions respectively.

5. The apparatus of claim 1 , the first and second signals passing through the refractive means twice when the refractive means is in its first and second positions respectively.

6. The apparatus of claim 1, the first, second, and third elements having light coupling ends which are substantially coplanar.

7. The apparatus of claim 1, the rotating means being contained within a close-fitting bearing cavity wherein normal rotation is unimpeded by the cavity, the cavity providing restraint and support to the rotor during extremely high g-load shocks enabling rotor pin bearings to survive severe shock loading.

8. The apparatus of claim 1, the rotating means comprising a magnetic circuit which includes a permanent magnet disposed within a cylindrical rotor, the refractive means being connected to the rotor and comprising a transparent cylinder having a cylindrical axis which is substantially perpendicular to a cylindrical axis of the rotor, the rotating means including means for stopping rotation of the rotor at first and second locations.

9. The apparatus of claim 1, further comprising:

a fourth optical element, the first element comprising an incoming network optical fiber, the second element comprising optical receiver means, the third element comprising an outgoing network optical fiber, the fourth element comprising optical transmitter means;

in the first position of the refractive means the outgoing fiber being optically connected to the transmitter means, zz and the incoming fiber being optically connected to the receiver means;

in the second position of the refractive means the outgoing fiber being optically connected to the incoming fiber, and the receiver means being optically connected to the transmitter means;

a loop back waveguide means for optically coupling the transmitter and receiver means when the refractive means is in its second position.

10. The apparatus of claim 1, further comprising a second switch including at least first, second, and third optical elements, the third element of the first switch and the first element of the second switch comprising a common optical fiber having no splices or optical connectors along a length thereof between its first and second opposite ends, and further comprising means for securing the first fiber end within the first switch, and means for securing the second fiber end within the second switch.

1 1. An optical switch apparatus, comprising a first switch, comprising:

at least first, second, and third optical elements;

means for rotating the refractive means between the first and second positions for switching an optical connection between the first and second element and the first and third element, a first angle a first optical signal makes with a normal to a surface of the refractive means through which the first optical signal travels as it passes through the refractive means when the refractive means is in its first position being substantially the same as a second angle a second optical signal makes with a normal to the surface of the refractive means through which the second signal travels as it passes through the refractive means when the refractive means is in its second position, the refractive means being rotated about its center of gravity.

12. The apparatus of claim 11, further comprising a second switch having at least first, second, and third optical elements, the third element of the first switch and the first element of the second switch comprising a common optical fiber having no splices or optical connectors along a length thereof between its first and second opposite ends, and further comprising means for securing the first fiber end within the first switch, and means for securing the second fiber end within the second switch.

13. An optical switch apparatus, comprising first and second optical switches, each switch comprising:

at least first, second, and third optical elements;

means for rotating the refractive means between the first and second positions for switching an optical connection between the first and second element and the first and third element; the third element of the first switch and the first element of the second switch comprising a common optical fiber having no splices or optical connectors along a length thereof between its first and second opposite ends, and further comprising means for securing the first fiber end within the first switch, and means for securing the second fiber end within the second switch.