JPH09105875A - Optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve inter-cycle repetitiousness, long term repetitiousness and an absolute arrangement error of a mechanical optical switch for optical fiber. SOLUTION: Optical fibers 152 are inserted into the inside of an input ferrule 144 and an output ferrule 146, and they are arranged in V grooves 140, 142 of holder structural bodies 120 shifting their positions. The ferrules 144 and 146 are rotated relatively, and a required input optical fiber is dressed with a required output optical fiber. Since the V grooves are covered by wear resistance thin leaves 132 and 134, the matter that the side walls of the V grooves are scraped by the rotation of the ferrules is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch, and more particularly, to a mechanical optical switch that rotatably couples an optical fiber of a first optical fiber array with an optical fiber of an opposing second optical fiber array. Regarding

[0002]

2. Description of the Related Art There are two types of optical switches, electronic optical switches and mechanical optical switches. Electronic optical switches are characterized by the absence of moving components, for example by acousto-optically or electro-optically shunting the light passing through the switch to perform the switching function.

On the other hand, a mechanical optical switch performs a switching function by physically moving an optical fiber element. The physical movement of the optical fiber within the mechanical optical switch is a lateral or rotational movement. One type of mechanical light switch uses a focusing element, such as a lens, to focus light from one fiber to another. The use of such an element increases the conversion error of the switch but significantly reduces the angular tolerance and increases the manufacturing cost. Other types of mechanical optical switches couple light from one optical fiber directly to another. The optical fibers are arranged facing each other with their end faces abutting each other. This design eliminates the focusing element and increases the angular tolerance, but significantly reduces the conversion tolerance of the switch.

[0004] US Patent No. 4,401,365 discloses that
A rotary optical switch in which a pair of opposing optical transmission path mounting members are arranged on the same rotation axis is described. One mounting member is fixedly mounted to the case, and the other member rotates on the central axis. Alternatively, the shaft may be secured to one of the mounting members that rotates about the shaft. Since the shaft or mounting member is directly connected to the motor, one mounting member is rotatable with respect to the other because the shaft or mounting member is rotated by the motor. The respective planes of the mounting members are adjacent to and face each other. The optical fibers are fixed in the respective mounting members such that the end faces of the optical fibers in the respective mounting members are concentric with respect to the rotation axis of the mounting members and exist on respective apparent circles of the same radius.

[0005] US Patent No. 5,037,176 discloses that
Others including first and second identical arrays of optical fibers that are held in axial alignment and are relatively rotatable about an axis of rotation for optical coupling or decoupling of the fibers in opposing arrays. A rotary optical switch is described. The optical switch has a cylindrical switch body that receives first and second identical arrays of optical fibers. The switch body is held in a coaxial arrangement by a split sleeve coupler. A tube surrounds the sleeve containing the fiber array,
A ring is placed between the sleeve and the tube to allow the index matching liquid to be retained within the switch to prevent back reflection. The optical switch described in this US patent is used in the optical switch assembly described in US Patent No. 5031994.

A key element of mechanical fiber optic switches (MFOS) is the precise alignment of opposing optical fibers in the switch. Currently, this requires that the switch components be manufactured with precise manufacturing processes and very precise tolerances. As will be described later, the current MFOS has difficulties in terms of cycle-to-cycle repeatability, long-term repeatability, and absolute arrangement of opposing optical fibers.

Mechanical fiber optic switches have unique bearing requirements not found in other types of applications. These special conditions need to be investigated to understand why current MFOSs do not provide proper alignment between switching fibers. Array tolerances for optical coupling between single mode optical fibers are well known,
It will not be detailed here. Assuming that there is no length or tilt adjustment error and the input and output fibers are equal, a fiber optic transmission with a lateral adjustment error is given by

(Equation 1) Note that x is the lateral offset, and w is the 1 / e ^ 2 radius of the emissivity pattern of the fundamental mode of the optical fiber. (M ^ n is
It means M to the n-th power. ) The derivative of Equation 1 gives the change in loss for a particular change in coupling efficiency.

(Equation 2) Reorder Equation 2 to solve for Δx as a function of lateral offset, fundamental fiber mode radius, and loss variation. The result is as shown in Equation 3.

(Equation 3)

Using the above equations and assuming that the switch transmission efficiency must be repeatable within 0.01 dB between cycles with a normal transmission loss of less than 0.50 dB, the maximum alignment error is between cycles. Is calculated in terms of repeatability, long-term repeatability and absolute alignment. Standard single
Since the 1 / e ^ 2 radius of the fundamental mode in the mode fiber is about 5.0 microns (μm), a nominal loss of 0.50 dB corresponds to a lateral alignment error of about 1.7 μm (Equation 1
According to). According to equation (3), the transmission change is 0 between cycles.
If it is less than 01 dB, the adjustment error of 1.7 μm is 0.0
Repeated in the range of 15 μm, ie 15 nm. Numerical tolerances are calculated for optical fibers with a mode field diameter of 5.0 μm. Other optical fibers have mode field diameters such as 5.1 or 5.6 μm. The different mode field diameters are
Change the numerical tolerance range slightly, not significantly.

The condition of 0.015 μm is only for cycle-to-cycle repeatability. There are long-term cyclic conditions in which the transmission efficiency must not change by more than 0.10 dB over about 100,000 cycles. When the same analysis is performed using Equations 1 and 3, the positional accuracy of the opposing fibers in the switch needs to be repeated in the range of 0.15 μm for a long period of time, that is, about 1/4 of the wavelength of visible light. .

FIG. 2 shows an idealized coaxial array and an actual coaxial array for a conventional mechanical fiber optic switch. FIG. 2A therein shows the end face of the cylindrical shaft 10 within the split sleeve 12. Ideally, the shaft 10 is perfectly round, its outer diameter exactly matches the perfectly round inner diameter of the split sleeve 12, and the shaft 10 contacts the split sleeve 12 along its entire circumference. The hole 14 formed in the shaft 10 for holding the optical fiber is perfectly round and concentric with the shaft 10 and the split sleeve 12. 2B and 2
C shows, in exaggerated scale, the shape of shaft 10, split sleeve 12 and bore 14 in actual imperfections.
None of the elements 10, 12 or 14 are perfectly round.
Instead, shaft 10 and split sleeve 1
2 can be approximated to a cylindrical surface, with a slightly larger or smaller radius in the local area. This is indicated by an ellipse in the figure. As can be seen, the split sleeve 12 and shaft 1
The contact points between 0 vary as one or the other rotates, or when a slight lateral torque is applied to the shaft 10, as shown by the dotted ellipse 16, the fibers within the shaft (not shown). No) does not draw concentric circles. Furthermore, at the point of contact, the surface of the split sleeve 12 is
Parallel to the surface of. The only force that keeps the shaft 10 from slipping into the split sleeve 12 is the frictional force between the two surfaces. Friction forces cannot provide the required degree of cycle-to-cycle or long-term repeatability. Furthermore, there is a contradiction in facilitation. It is desirable to smooth them in order to extend the life of the bearing surfaces, but this smoothing results in less wobbling as a result of reduced friction between the two surfaces.

2B and 2C also show another problem. The fibers are aligned with respect to the shaft 10 through holes 14 drilled along the axis of the shaft 10, which holes 14 have their own set of tolerances. In particular, the hole 14 is slightly concentric with the outer surface of the shaft 10 and is not as slightly round as the outer surface of the shaft 10.

If the input and output fibers of the switch rotate on the same circle, which is exactly concentric, there are several dimensional tolerances that need to be precisely defined. The design parameters that must be reliably adjusted are as follows. Roundness of outer diameter of input shaft Roundness of outer diameter of output shaft Roundness of inner diameter of input shaft Roundness of inner diameter of output shaft Concentricity of inner diameter and outer diameter of input shaft Inner diameter and outer diameter of output shaft Diameter concentricity input shaft outer diameter input shaft inner diameter output shaft outer diameter output shaft outer diameter split sleeve inner diameter split sleeve inner diameter roundness input and output fiber diameter input and output fiber concentricity

To keep the insertion loss at 0.50 dB, the adjustment error added by all these tolerances should be less than about 0.17 μm. This is a fairly difficult task, and to achieve this some dimensional tolerances of the individual elements (input fiber, output fiber, input shaft, output shaft and split sleeve) are sub-μm. It is necessary to be. This, of course, does not minimize the cost of the individual parts and is laborious in terms of manufacturability.

[0014]

Another problem with mechanical fiber optic switch design is switch repeatability. FIG.
Is the shaft 10 and sleeve 12 of FIGS. 2B and 2C.
Figure 12 is a side view of the sleeve 12 shown in cross section.
Split sleeve 12 is sleeve 1 that cannot be unfolded
Works with a shaft 10 that is slightly larger than the inner diameter of 2. Since the sleeve 12 has a tear, the sleeve 12
Allows the shaft 10 (the ferrule containing the optical fiber) to fit slightly inside the sleeve without play of the diameter. A play in diameter causes tilt in the bearing and is undesirable, and non-repeatability of alignment errors between opposing fibers must be less than 0.015 μm to meet cycle-to-cycle repeatability specifications.

As described with reference to FIGS. 2B and 2C, if the roundness of the portion of the shaft 10 and the sleeve 12 is not sufficient, the fiber moves in a non-circular curve.
However, apart from bearing wear, insufficient roundness has no adverse effect, ie, lack of repeatability. Insufficient roundness adversely affects overall binding efficiency but not repeatability. FIG. 3 shows the shaft 10 having an interference fit against the sleeve 12. However, the second shaft 18 tends to differ slightly in diameter due to unavoidable tolerances during manufacture. If the diameter of the second shaft 18 is larger than the first shaft, the split sleeve 12 expands slightly, providing an interference fit with the second shaft 18 rather than the first shaft 10. The first shaft 10 is now attached to the split sleeve 12
You can slip inside. If the second shaft 18 has a smaller diameter than the first shaft, it wobbles. In either case, one of the two shafts 10 or 18 wobbles within the split sleeve 12. To meet the cycle-to-cycle repeatability requirement, wobble must be less than 0.015 μm, and therefore the diameter of the two shafts 10 and 18 should be about 0.008 μm. This specification requires extremely expensive components. However, it is not feasible to meet this specification, all for practical purposes.

Thus, there is a need for an inexpensive mechanical fiber optical switch that meets specifications for inter-cycle repeatability, long-term repeatability, and absolute alignment error. Such a switch must use easy-to-purchase off-the-shelf components and be readily assembled without the need for precise alignment of the switch components and fibers. In addition, the switch must have a fiber mounting device that minimizes bearing wear and is insensitive to component dimensional differences. Furthermore,
The switch must have good stability with respect to temperature changes.

Therefore, an object of the present invention is to provide an inexpensive optical switch for optical fiber which satisfies the specifications of cycle-to-cycle repeatability, long-term repeatability and absolute array error.

[0018]

The optical switch of the present invention rotates about an independently offset (offset) first axis of rotation and is positioned on at least one first closed curve. It has one optical transmission line and at least one second optical transmission line which is rotated about an independently offset second rotation axis and is positioned on a second closed curve. The first and second optical transmission lines are in a facing relationship and form an optical interface with a closed curve of the optical transmission lines laterally offset from each other to establish an intersection on the closed curve. First and second mounting members are provided to hold the corresponding first and second optical transmission lines. At this time, the first mounting member has a rotating shaft that is axially arranged with the first rotating shaft that is independently offset, and the second mounting member is axially arranged with the second rotating shaft that is independently offset. It has an axis of rotation arranged. The first and second optical transmission lines are at positions displaced from the respective rotation axes of the mounting member. Means are provided for accumulating angular coordinates representing the intersections of the first and second closed curves of the first and second optical transmission lines, respectively. At one of the intersections on the closed curve, the first and second optical transmission lines are axially arranged to provide means for coupling the measuring instrument to the fiber link. It uses drive motors coupled to respective mounting members to selectively direct the first and second optical transmission lines relative to each other about respective independently offset axes of rotation in response to angular coordinates. Rotate to.

Also in accordance with the present invention, the retaining members are disposed within individual kinematically designed offset holder assemblies. In the preferred embodiment, a V-groove structure that forms a V-shaped cavity to receive each retaining member and that has apex and angled sidewalls provides dynamic attachment. A spring fastener is positioned over the V-shaped cavity to secure the retaining member to the three-point cavity. The V-groove structure is formed of a material having a hardness about the same as or higher than that of the holding member, or a sidewall and a spring clamp of the V-groove structure having a hardness of about the same as or higher than the holding member. It has an insert fixed to the tool. The retaining member and V-groove structure are preferably borosilicate, a ceramic material. The insert is preferably a hard material such as ceramic or sapphire.

In a preferred embodiment, the retaining members are first and second ferrules, each ferrule having a major axis centered about which the ferrule rotates, an outer diameter, and a first ferrule.
And a central hole for accommodating the second optical fiber. The optical fiber is loaded into the ferrule such that any one of the optical fibers exists on the rotation axis of the ferrule that does not move on the closed curve. In addition, the optical interface end of the ferrule has a sleeve member of ceramic material that, when polished, allows separation between the first and second optical fibers. Alternatively, the ferrule may be made of a ceramic material that is harder than the inner optical fiber.

Axial arranging means selectively rotates the first and second optical transmission lines relative to one another with respect to their respective independent and offset axes of rotation. Means are provided for accumulating angular coordinates representing the intersections of the first and second closed curves of the first and second optical transmission lines, respectively. The rotating means includes first and second rotating means for coupling the rotating movement to the respective first and second optical transmission lines.
Includes high resolution first and second stepper motors or DC motors responsive to the angular coordinates of one of the intersections of the closed curve.
A spur gear attached to each stepper motor or DC motor has a second rotational movement attached to a rotating shaft.
It is transmitted to the rotating shaft via a spur gear. The rotating shaft is coupled to a holding member of each optical transmission line. The rotating shaft includes a first shaft element having a central hole for accommodating the first and second optical transmission lines, respectively, and a flexible drive shaft for connecting the first drive shaft element to a holding member of each optical transmission line. Including. Also included are first and second bearings having a central bore for receiving the first shaft element of the rotary drive shaft. Alternatively, the rotating means may be a manual rotary reduction gear assembly that is coupled to transmit rotary motion to each of the first and second optical transmission paths.

The method of axially aligning (arranging axially) the optical transmission lines facing each other of the optical switch is a method of responding to the angular coordinate representing the position of the first optical transmission line at the intersection on the first closed curve. Step (1) of rotating the first optical transmission line on one closed curve to one of the intersections, and step (1) in response to the angular coordinate representing the position of the second optical transmission line at the intersection on the second closed curve. )
The step (2) of rotating the second optical transmission line on the second closed curve at the intersection corresponding to the intersection at. In the preferred method, these steps are performed simultaneously. An additional step in arranging the opposing optical transmission lines is to select the intersection on the closed curve closest to the optical transmission line before rotating the first and second optical transmission lines to the selected intersection.
Another set of steps for arranging the opposed optical transmission lines is the step (1) of rotating each of the first and second optical transmission lines by the same amount after the selected intersection and the first and second optical transmission lines. And (2) stopping the optical transmission line at the same point at the intersection by reversely rotating the lines at the same time. In an optical switch having a plurality of optical transmission lines that rotate about one or both independently offset axes of rotation, an additional step is to extract one of the optical transmission lines from the plurality of optical transmission lines. Is to choose.

Certain conditions may occur in which the optical switch can be destroyed. A further step is to generate an interrupt signal for stopping each drive motor when the drive motor passes each home position (origin position), and generate an error code to the user when this state occurs. An additional confirmation step is performed when one of the plurality of optical transmission lines is selected. The selected optical transmission line must be within the selection limit obtained by the number of optical transmission lines in the plurality of optical transmission lines. A user error code is generated when the optical transmission line selected from the plurality of optical transmission lines is out of the selection limit. Including another step, the angle coordinate of the current optical transmission line intersection and the newly selected angular coordinate of the optical transmission line are added to determine whether the added angular coordinate exceeds the maximum range value. When this happens, a user error code is generated.

The optical switch can be used in remote fiber test systems. This fiber test system
At least one first measurement test device for testing an optical fiber link having an optical transmission fiber; an optical test fiber; and at least one first connection for remotely connecting the measurement test device to one end of the optical fiber link. It has an optical switch. This optical switch has an independently offset first
At least one that rotates about an axis of rotation and positions the first optical transmission line on the first closed curve and is coupled to the measurement tester;
At least one first optical transmission line and at least one that is rotated about an independently offset second rotation axis to position the second optical transmission line on a second closed curve and couple to the optical fiber link. Second optical transmission line of These first and second optical transmission lines are in a facing relationship forming an optical interface, and the closed curves of the optical transmission lines are laterally offset from each other and make an intersection on the closed curve. The first and second mounting members maintain the respective first and second optical transmission lines. The first mounting member has a rotating shaft that is axially aligned with the independently offset first rotating shaft, and the second mounting member is a rotating shaft that is axially aligned with the independently offset second rotating shaft. Have. The first and second optical transmission lines are positioned so as to deviate from the respective rotation axes of the mounting member. Means are provided for accumulating angular coordinates representing the intersections of the first and second closed curves of the respective first and second optical transmission lines. At one of the intersections on the closed curve, the first and second optical transmission lines are aligned and a drive motor coupled to each mounting member is used to rotate independently around an axis of rotation that is offset according to angular coordinates. Means are provided for selectively rotating the first and second optical transmission lines with respect to each other to couple the measurement tester to the fiber optic link. An optical coupler, such as a wavelength division multiplexer, couples the second optical transmission line to the optical test fiber. The measurement tester may be an optical time domain reflectometer, optical power meter, SDH / SONET test set, or the like. An optical switch for a remote fiber test system is provided to rotate multiple optical transmission lines around one or both independently offset axes of rotation to couple multiple measurement test instruments to multiple fiber optic links. .

Other objects, advantages and novel features of the present invention will be understood from the following detailed description with reference to the claims and the accompanying drawings.

[0026]

1 shows a mechanical optical switch 2 according to the invention.
0 shows an enlarged perspective view of 0. The switch 20 is used, for example, in a remote fiber test device. In this device, switch 20 connects remote test equipment, such as an optical time domain reflectometer, optical power meter, etc., to various optical fibers and evaluates these fibers. Another example of use is in connection with a central office telephone switch for redirecting telephone signals to different optical fibers when the transmission line is down.

The switch 20 has a housing 22 consisting of a base 24, end walls 26, 28 and side walls 30 forming a partial cavity. Within the cavity 32, a central platform 34
And the bearing support portion 36 stands up from the base portion 24. The bearing support 36 includes the center base 34 and the end wall 2.
It is arranged between 6, 28. Removable side walls 38 and top plate 40 are provided to surround the housing cavity. A circuit board 42 containing the electronic circuitry for the switch 20 is mounted on top of the housing 22. The electronic circuit has a single or multiple storage elements and holds the angular coordinates associated with the intersection point on the closed curve between two opposing optical fibers. The electronic circuitry also includes logic circuitry that enables requests and functions to the switch, and generates interrupt instructions and user error codes to deactivate the switch function. Stepper / motor mount (bracket) 44
Is secured to the outside of housing 22 adjacent end walls 26 and 28. The stepper motor 46 is attached to each fixture 4
Fixed to 4. The shaft to which the spur gear 48 is fixed is
Extending from each stepper motor 46. A photodetector fixture (bracket) 50 is attached to the outside of each end wall 26 and 28. A light detector 52 having a light emitting element and a light receiving element is attached to each fixture.

A hole 54 is formed in each end wall 26 and 28. The bearing 56 is press-fitted into each hole 54 from the cavity 32 side of the end walls 26 and 28. The bearing 58 is pressed into the bearing support 36. A flange shaft seal (not visible in this view) is mounted in each hole 54 from outside cavity 32 and held in place by a seal plate 60 mounted outside each end wall 26 and 28. . Central hole 6 for accommodating input and output optical fibers 66 and 67
A rotatable drive shaft 62 having a sealing plate 6
0, flange shaft seal and bearings 56 and 5
Extends through 8. A slotted rotor 68 having a slit 70 is attached to each drive shaft 62. Part of each perforated rotor 68 is the photodetector 5
The two light emitting elements and the light receiving elements are arranged in a gap. A drive shaft spur gear 72 that engages each spur gear of the stepper motor 46 is mounted on the rotatable drive shaft 62. Flexible drive shaft coupler 74 is secured to one end of each drive shaft 62. The mounting member (not visible in this view) that holds the optical fibers 66 and 67 of the switch 20 is in the other end of the flexible coupler 74. A spring clamp 76 is attached to the pedestal 34 to retain the attachment member in an offset V-groove formed in the central pedestal 34. The spring fastener 76 and the offset V-groove form a holding structure for a mounting member described below. The enclosed cavity 32 is filled with a suitable index matching liquid to reduce back reflection of the input light passing between the input and output fibers. The refractive index matching liquid also serves as a lubricant for the V groove and the bearing 58.

The housing 22, removable side wall 38 and top plate 40 are made of a material such as machined aluminum, stainless steel, or molded plastic. In the current design, these parts are machined aluminum. The rotating means, which is the stepper motor 46, is required to have a rotation accuracy of 0.14 degrees, be inexpensive, have relatively low power, and be small. An example of such a stepper motor 46 is manufactured and sold under the part number HSA33700 by HSI, Inc. of Watterbury, Connecticut, USA. This particular stepper motor has an angle control specification of 0.09 degrees. Since this stepper motor has a large backlash, the home position indicator is the photodetector 52.
And a perforated rotating body 68. Photo detector 52
Is an electric signal that is generated when light is transmitted from a light emitting element to a light receiving element, and may be a commercially available photodetector such as GP1L01F type manufactured and sold by Sharp Corporation. The perforated rotor 68 may be made of any suitable material that has suitable rigidity and is capable of forming a narrow hole therein. In the preferred embodiment, the perforated rotor 68 has 0.001 inch (0.0254 millimeter) slots (slits).
It is formed from a 1 mil (2.54 / 1000 centimeter) polycarbonate film with 70. The films are laminated to form an aluminum hardened plate. Instead of the stepper motor 46, a DC motor having a high resolution encoder may be used. The ferrule drive shaft 62 may be formed of any suitable hard and abrasion resistant material. In the preferred embodiment, rotary drive shaft 62 is a quarter inch (6.35 mm) outer diameter stainless steel rod. The diameter of the central hole 64 is 1/10 inch (2.54 mm).

FIG. 4 is a perspective view of a mounting member driving device for the mechanical optical switch 20. This drive has an input 80 and an output 82 that are identical except for the positioning of the optical fiber within the mounting member, and for these ferrules 86
It will be described in detail in connection with. The components of the output unit 82 are substantially the same as those of the input unit 80. The output section 82 has a rotary drive shaft 62 attached to the perforated rotating body 68 and the drive shaft spur gear 72. Drive shaft 62 passes through seal plate 60, flange shaft seal 94 and bearings 56, 58. Flexible drive shaft coupler 74
Is attached to one end of the drive shaft 62. Flexible coupler 74 is provided to reduce the lateral torque applied to ferrule 86 during rotational movement. This torque causes an optical fiber alignment error in the switch 20. A suitable flexible coupler is sold as part number FC-9 by the Servometer Company of Cedar Grove, NJ, USA. The ferrule 86 contained within the ferrule structure 88 is secured to the opposite end of the flexible coupler 74. The optical fibers 66 and 67 of the switch 20, which are in close contact and opposed to each other, are fixed in each ferrule 86. To maintain this relationship, a retaining collar 96 is attached to the ferrule drive shaft 62 on either side of the inner bearing 58 to form a flexible coupler 74 and compress the end face of the ferrule 86. Keep in the state.

FIG. 5 is an exploded perspective view of the mounting member drive assembly. In this figure, the same components as those in FIGS. 1 and 4 are designated by the same reference numerals. The ferrule structure 88 includes a ferrule coupler 90 and a ferrule 86. In the preferred embodiment, ferrule coupler 90 is formed of stainless steel, but other suitable materials may be used. Alternatively, the ferrule strain relief 92 is secured within the ferrule coupler 90. Representative ferrule release unit 92
Is sold as part number A3215 by Sympton Corp. of Bayport, NY, USA. The ferrule 86 is fixed in the ferrule coupler 90. The ferrule 86 is formed of borosilicate industrial optical glass. A representative ferrule is HC from Nippon Electric Glass, Inc. of Death Plains, Illinois, USA.
It is manufactured and sold as a mold. Specified ferrule has an outer diameter tolerance of ± 5 μm, deviation from roundness specifications (roundness) ±
It is 1 μm and the inner diameter tolerance is ± 2 μm. As mentioned above, the use of ferrules with these tolerances in conventional optical switches does not provide the cycle-to-cycle repeatability, long-term repeatability, and absolute alignment required of usable mechanical optical switches. . However, in the mechanical optical switch 20 of the present invention, instead of arranging and rotating the ferrules coaxially with respect to a single axis as in the conventional case, by shifting the ferrule 86 so as to rotate with respect to the separate axes, the conventional optical switch 20 is provided. The problem of mechanical tolerance of mechanical optical switch is solved.

FIG. 6 shows two opposing ferrules 100 and 10 rotating about independent axes 104 and 106.
2, the ferrules 100 and 102 include optical fibers 108 and 110, respectively, which serve as optical transmission lines.
In a preferred embodiment, the optical fiber has a core diameter of about 10
It is a single mode fiber having a diameter of 125 μm and an outer diameter of 125 μm. Other optical transmission lines, such as multimode optical fibers, may be used without departing from the spirit of the invention. Opposing optical fibers 108 and 110 are the ferrules 100.
And 102 are arranged to move along a closed curve as they rotate. The closed curves 112 and 114 intersect at points 116 and 118 on the respective curves. Closed curve 112
And 114 are closed through the 360 degree rotation of ferrules 100 and 102, and intersection 116
And 118 are stable and represent exactly the optimal alignment position for the two opposing fibers 108 and 110.

7A and 7B show a mechanical optical switch 2
0 shows one of two offset holder structures 120 formed or attached to the base 34. Each holder structure 120 includes a V-groove structure 1 having vertices 124 forming V-groove cavities 130 and angled side walls 126, 128.
22. The sidewalls 126 and 128 have strips 132 of wear resistant material such as glass or ceramic.
And 134 are glued together. In this way, the holder structure 1
By configuring 20, the V-groove structure 122 can be formed of an inexpensive material such as aluminum or plastic, and at the same time, an extremely durable bearing can be obtained.
A more expensive but designable option is to utilize V-grooves made directly from wear resistant material.

The substantially out-of-round ferrule 86 shown for purposes of illustration is a V formed on the pedestal 34.
Each is received in each of the groove cavities 130. Spring fastener 7
6 is located on cavity 130 to secure ferrule 86 in V-groove structure 122. Each V-groove structure 122
The sidewalls 126 and 128 of the have two contacts to the ferrule 86 and a third contact to the spring fastener 76. This three-point installation is kinematically correct. Kinematic attachment as used herein means attachment by all forces resolved by simultaneous points. The retaining surfaces or sides 126, 128 and spring fasteners 76 are tangent to the surface of ferrule 86, resulting in a very stable minimum energy structure, even if ferrule 86 is not perfectly circular. This is as follows when compared to conventional switches where the number of contacts is unknown and the number of contacts changes between switches even during rotation. The spring fasteners 76 within each holder assembly 120 can be easily moved in small increments to accommodate thermal expansion of the ferrule 86 or deviation from the circle without sloping the ferrule itself. be able to. Even if the ferrule 86 is significantly out of round, the fiber in the ferrule will still follow a closed curve. This eliminates any wobble found in conventional mechanical optical switches due to dimensional differences between ferrules. The practice of the present invention is not strictly limited to V-groove structures and fastener configurations; other kinematically accurate holder structures are also
It can be used without departing from the spirit of the invention.

Bearing wear is an important issue in any mechanical optical switch 20. Bearing wear of the V-groove structure 122 occurs only along a fine line on the surface of each sidewall 126 and 128. However, wear of the ferrule 86 occurs along its entire surface. The wear rate of the V-groove structure 122 is hundreds or thousands of times greater than that of the ferrule 86 when the thickness of the material removed by wear is inversely proportional to the area of the bearing. Wear the wear-resistant flakes 132 and 134 on the side wall 1
Adhering to 26 and 128 reduces wear of V-groove structure 122. Further, the control of the switch is designed so that on average both ferrules 86 rotate the same angle during any 100,000 cycles. This would, in theory, result in equal wear rates for both V-groove bearings, and the ferrule 86 would have the same amount in each V-groove structure 12
2 to maintain their relative alignment.

FIG. 8 shows the base portion 34 of the mechanical optical switch 20.
It is a perspective view which shows the offset V-groove holder structure 120 formed above. Input and output fiber optic arrays 148
And 150 including input and output ferrules 144 and 1
46 is mounted in V-grooves 140 and 142. Each fiber array 148 and 150 is formed from a single optical fiber 152 or multiple optical fibers. The outer walls of ferrules 144 and 146 and spring fasteners 76 are not shown for clarity. Abrasion resistant flakes 1
32 and 134 are presently preferred configurations in which separate wear resistant flakes are adhered to opposite ends of the sidewalls 126 and 128 of the V-groove 140 to form a dual end bearing for ferrules 144 and 146. Indicated by. A spring fastener 76, such as that shown in FIG. 1, includes first and second spring fastener members disposed on each set of wear resistant strips for securing ferrules 144 and 146 within V-groove cavity 130. An elongated hole (slot) is drilled to form the. Instead, the wear resistant flakes 132 and 134 are configured to align all sidewalls of the V-groove 140. As shown, the input ferrule 144 is slightly offset from the output ferrule 146. Since each ferrule 144 and 146 is constrained within the kinematically accurate holder assembly 120, each fiber 152 of the input fiber array 148 follows a closed curve as the input ferrule 144 rotates.
Although these curves are approximately circular, the actual shape of the curves is not important. The curve may be an ellipse or a closed curve of any similar shape. The same is true for optical fiber 152 of output fiber array 150. Input and output fiber array 1 as described with reference to FIG.
The closed curves of the optical fiber 152 in 48 and 150 are not concentric. That is, any optical fiber 152 arranged to move on a closed curve within the input fiber 148.
Is not symmetrical with any optical fiber 152 arranged to move on a closed curve in the output fiber array 150. The V-grooves 140 and 142 are purposely offset to make the closed curves of the input and output optical fibers non-concentric.

Since the closed curves of input and output fiber optic arrays 148 and 150 are not concentric, they intersect at two points. This results in a perfect alignment between the optical fibers 152 of the input optical fiber array 148 and the output fibers 152 of the output optical fiber array 150. The kinematically correct holder structure 120, which is a ferrule bearing, has no wobble or slop, so the curves are actually closed, and since they are closed, the angular coordinates of the intersection are stable. This is because, for some angular coordinates of the input and output ferrules 144 and 146, the optical fibers 152 of the input fiber array 148
Means perfectly aligned with the optical fiber 152 of the output fiber array 150 at the intersection. Since the curve is closed, the angular coordinates are stable. These repeat many times with extreme accuracy. Dynamically, when the trajectory of the phase space coordinate system is closed, the trajectory is stable, periodic, and predictable. But if the trajectory is not closed, the coordinate system becomes chaotic.

An important advantage is obtained by offsetting the input and output ferrules so that they rotate about independent and distinct axes of rotation. Each ferrule 144 and 146 may be loaded with any number of fibers 152. Some of the fibers 152 are positioned around the inside diameter ends of ferrules 144 and 146, and some are positioned toward the center. By offsetting the ferrules 144 and 146, the closed curve drawn by the input fibers along the ends of the ferrule 144 will intersect all of the output fibers of the ferrule 146 even though they are further centered. it can. To do this, nominally the closed curve tracked by the input fiber is 1 /
The two ferrules 144 and 146 are offset so that they intersect the center of the output ferrule within the tolerance of the two fiber diameters. In conventional designs, an output fiber located near the center cannot be connected to an input fiber at the end. This means that an N × N switch can be configured with a larger number of its fibers concentrated towards the center than is possible with a conventional mechanical optical switch. This is an important advantage and objective of the present invention, as the fiber moves further from the center of the ferrule, and the angular tolerance required to perform a particular alignment decreases. Therefore, a more accurate angular resolution of the device that rotates the ferrule when the fiber is off center of the ferrule is needed. This requires, for example, the use of expensive stepper motors 46 in conventional designs, while the present invention allows the use of less precise or inexpensive stepper motors 46.

Another advantage and object of the present invention is to provide optical fiber 1 in input and output fiber arrays 148 and 150.
52 may be randomly configured within the input and output ferrules 144 and 146. That is, the fibers 152 in the arrays 148 and 150 need not be arranged in an orderly small pattern. Each fiber can follow its own closed curve. Input fiber array 1
As long as the closed curves of all 48 input fibers 152 intersect the closed curves of all output fibers 152 of the output fiber array 150, there is no difference in the operation of the switch. This design is comparable to the conventional one where something is needed to hold or position the fiber against the inner surface of the ferrule. Furthermore,
Something that traditional needs to be very accurately dimensioned, but if the fibers are not held tightly, this will adversely affect the concentricity, diameter and roundness of the circle, causing these fibers to move. I will end up.

It is an object of the present invention to provide a mechanical optical switch 20 which is easy to manufacture. As described above, there is no need to accurately position the individual fibers 152 of the input and output fiber arrays 148 and 150 within the input and output ferrules 144 and 146 of the switch 20.
The switch 20 of the present invention may be comprised of a single 1 × N switch having a single input port and multiple output ports, or the switch 20 may have a single input port and multiple output ports. It may be composed of N × N or N × M switches. Regardless of the configuration, the optical fiber 1
The positioning of 52 is similar. In the 1 × N switch, the input ferrule 144 is loaded into the optical fiber 152. Add epoxy resin to ferrule 144,
Fill the gaps between the plurality of files 152. Then, all but one of the optical fibers 152 is a single optical fiber 15
It is cut at the end of the ferrule 144 whose optical port is 2. With the exception that the number of fibers 152 to be cut is small or not at all, the same processing is performed by N × N.
And N × M optical switch. Similarly, the same process is used to form the output ports of switch 20. What is important here is that precise positioning of the fiber 152 within the ferrule 144 is not required. This substantially reduces the manufacturing cost of the switch 20.

Alternatively, a plug device may be used in forming the optical port of the switch 20. The plug is positioned in ferrules 144 and 146, and fiber 152 is positioned between the plug and the side wall of the ferrule. The epoxy resin is used to fill the ferrules 144 and 146. In either process, the ends of ferrules 144 and 146, including fiber 152,
Rubbed and polished.

The input and output ferrules are the switch 20.
Mounted in the holder assembly 120 of the ferrule drive shaft 62 and connected to the ferrule drive flexible coupler 74 with the input and output fibers 66 and 67 (FIG. 1) through the central bore 64 of the ferrule drive shaft 62. The structure of the mechanical components of the switch is based on the input and output ferrules 144 and 146.
Independence from the position of the optical fiber 152 within is not critical. As an example, the perforated rotor 68 is mounted on the ferrule drive shaft 62 regardless of the position of the fiber 152 within the ferrules 144 and 146. By positioning the hole (slot) 70 of the rotating body 68 with respect to the photodetector 52, each ferrule 14
A starting reference point is determined for fibers 152 in 4 and 146. Sidewall 38 is secured to housing 144 and cavity 32 is filled with a suitable index matching liquid. The top plate 40 is secured to the housing and the switch 20 is ready for alignment processing.

FIG. 9 shows a typical alignment (axis alignment) adjusting device for obtaining the intersection of the closed curve of the output optical fiber and the closed curve of the input optical fiber. Note that virtually any fiber 152 residing on the axis of rotation of either ferrule 144 or 146 does not move on the closed curve and acts as a point. For this reason, ferrule 14
Any fiber 152 on the axis of rotation of either 4 or 146 is not used as an optical port. The array adjusting device includes a controller 160 such as a computer and a controller 1310.
nm or 1550 nm laser source 162, single mode coupler 164, and two optical power meters 16
6 and 168, an electronic switch 170, and a group of photodiodes 172. Computer 160 controls both optical switch 20 and electronic switch 170 and records the analog signals from power meters 166 and 168. The computer determines the angular array coordinates of each port on the optical switch 20 by following the procedure illustrated by the flowcharts shown in FIGS. The threshold values used in this procedure may vary from device to device, depending on the laser source used, the type of photodiode used, and the type of power meter used. Not specified.

The basic alignment procedure uses a mathematical model to couple between two alignment errored Gaussian beams. This model is a single
It is a good approximation for optical transmission between mode fibers. That is because the fundamental mode of these fibers is close to Gaussian. This model assumes that the two optical fibers are exactly the same, with no length or angle error between them. Ferrules 144 and 1
46 is rubbed and polished before being incorporated into the switch 20, and the stop collar 96 is used to keep the ferrules 144 and 146 in opposite contact, so the above assumption is valid. Is. The mathematical model is shown above in Equation 1 where T is the optical transmissivity, x is the lateral offset between the two fibers, and w is 1 / e ^ 2 of the fundamental mode emissivity profile. There is. FIG.
Shows this function plotted against a logarithmic scale. This function has a single maximum obtained when the two optical fibers are exactly coaxial. In this procedure, the maximum value is determined by moving the first fiber, and secondly, the optical transmission of the switch is maximized.

For the smooth curve shown in FIG. 12, the interactive procedure of FIGS. 10 and 11 steadily approaches the maximum and the two fibers are correctly aligned. However, in practice, the curve becomes rough below a certain level and at low light levels the curve has a local maximum that changes the procedure. These local maxima are significantly lower by 20-30 dB than the global maxima, and the procedure does not need to be adapted to them or the switch insertion loss is high. This is because the procedure has large steps (either clockwise or counterclockwise) when the transmissivity is below a certain local maximum threshold, the threshold called LMT. These small local maxima are usually only a few degrees wide, and by searching in 5 or 10 degree steps, the procedure avoids them, usually within 5 degrees of the global maximum, the LMT. Find it at the top of.

Preliminary searches in large steps reduce the risk of inadvertently arranging the switches to local maxima, but the procedure is not very simple. As a special precaution, the procedure looks at the absolute power transmitted before determining if the ports are properly aligned. If the absolute power is too low but cannot be improved by adjusting the two motors (in the smallest increments), either switch has a defective element or is aligned to a local maximum. When this situation occurs, the procedure is as shown in FIGS.
Use a special program that solves the subroutine labeled 1 in the flowchart.

The problem solving subroutine uses the information about how bad the transmission efficiency is to perform other searches using increments greater than the minimum stepper motor step and less than 10 degrees. The LMT is considered to be adjustable when the problem is extremely rare and difficult for experienced operators, such as when the procedure simply attempts to line up with other ports.

When aligning a switch with multiple ports, it is impractical to try to align the ports in sequence. Instead, it is straightforward to look at each of the output ports by measuring the light power at each of the photodiodes to see which is closest to the input port, and arrange it first. After arranging the first port, this procedure arranges the next closest port. Normally, this procedure does not arrange the output ports in order, but it is faster. And this procedure is
Always renumber the ports after completing the sequencing procedure.

The procedure begins with the controller 160 rotating the input and output ferrule drive shafts 62 to their home position. These origin positions are the photodetector 5 when the slot 70 of the perforated rotary body 68 allows light to pass between the light emitting element and the light receiving element of the photodetector 52.
Corresponding to the electric signal from 2. This procedure is step 1
At 80, electronic switch 170 is set to port 1 and input ferrule 144 is rotated to maximize the optical signal at photodiode 172 of port 1. next,
The output ferrule 146 is rotated to maximize the optical signal (step 182). If the optical signal is greater than the threshold (step 184), the optical signal is maximized again by sequentially rotating the stepper motor 46 for the input and output ferrules 144 and 146 using the smallest step increments (step 186). And 188).
These steps are repeated until the optical signal stops increasing (step 190). If the insertion loss is within specifications (step 192), then the ports are aligned. Each stepper motor 46 is adjusted from its respective origin position and the angle value is stored in a memory arranged on the circuit board 42 attached to the switch 20. Electronic switch 170 is set to the next port and ferrules 144 and 146 are set to their home position (step 19).
4) This process is repeated for the next port (step 180).

After the first motor rotation, if the optical signal is below the threshold (step 184), this procedure causes motor 1 to rotate clockwise (clockwise) within 10 degrees and motor 2 to rotate. The rotation maximizes the optical signal (step 196). If the optical signal does not improve, the motor 1 moves counterclockwise (counterclockwise direction) 2
Rotated counterclockwise within the range of 0 degrees, motor 2 is rotated to maximize the optical signal (step 200).
The motor 1 rotates about 10 degrees clockwise or about 20 degrees counterclockwise.
Once the optical signal improves (steps 198 and 202) after maximizing the optical signal by rotating the motor 2 by rotating the motor 2 (steps 198 and 202), this routine maximizes the optical signal on the motor 2 and continues in the proper direction. Yes (steps 204 and 20)
6). After this process, if the optical signal is above the threshold, the routine jumps to the portion of the procedure where motors 1 and 2 were adjusted using the minimum increment (step 1).
86 and 188). If the optical signal is greater than the insertion loss (step 192), the ports are aligned (step 19).
4) Otherwise, the routine jumps to a routine that solves the particular problem (step 186). After clockwise and counterclockwise rotation of the motor, if the light signal is less than the threshold (step 210), the routine jumps to a routine that solves the special problem (step 186).

The procedure of FIGS. 10 and 11 is designed to find one of two intersections on the closed curve of the input and output optical fibers forming the optical port. This procedure can be easily modified to find two intersections. This is convenient for switching between the ports of the optical switch 20 more quickly, so that the closest intersection of the designated port is accessed more quickly. Further, the procedure just described is for the fiber 15 in ferrules 144 and 146.
We assume a blind search where we do not know anything about the position of 2. An improved apparatus and method for aligning fibers within ferrules 144 and 146 is shown in FIGS. The alignment device is the analysis station 22 shown in FIG.
0 and the measurement alignment station 230 shown in FIG. The analysis station 220 includes a light source 221 such as frosted florescent light and an optical microscope 222 manufactured by Buehler and used to test the ferrules of fiber optic connectors. This microscope is used with a 5 × objective for alignment in accordance with the invention. Input and output ferrule 14
Depending on the number of fibers 152 in 4 and 146, the magnification of the objective lens may be greater than or less than 5 times. For example, for a mechanical optical switch 20 with a small number of ports,
A 10 × or 20 × objective lens is used, and for the mechanical optical switch 20 having a large number of ports, a 2 × objective lens is used. Monochrome CCD such as KP-M1 manufactured by Hitachi Electronics Co., Ltd.
The camera 223 is coupled to the microscope 222. The output of CCD camera 223 couples to a video monitor 224.
This monitor is a VM920 / VM9 manufactured by Hitachi Electronics Co., Ltd.
Type 21 may be used. The output of this video monitor 224 is
CAT-made by Computer Eisult (EYESLPT)
It attaches to a frame grabber 225 such as a 100 model.
The output of this frame grabber 225 is coupled to computer 226. The computer runs Frame Grabber software from Computer Aisult. The measurement alignment station 230 comprises a solid state laser 231, such as a 1310 nm or 1550 nm laser for use in telecommunications transmission equipment, a power meter such as a Tektronix TFC200 optical power meter, and a computer 234. . Each of the computers 226 and 234 may be connected via a network, or both stations may share a single computer. Regardless of the configuration of the individual computers 226 and 234, the measurement alignment station 230 uses the data output of the analysis station 220 to align the opposing fibers 152 within the ferrules 144 and 146.

The analysis station 220 comprises an optical fiber
Images of the respective end faces of the input and output ferrules 144 and 146, including the arrays 148 and 150, are captured to determine the center of each fiber 152 in the ferrules 144 and 146, the axis of rotation of each ferrule 144 and 146, and the inside of each ferrule. The angular alignment coordinates of each fiber 152 in each ferrule with respect to the reference point are determined. The reference point for each ferrule is a fixed point within the ferrule that is recognizable in the captured image. In the preferred embodiment of the alignment procedure, the reference point is the multimode fiber, hereafter referred to as the reference port. This multimode fiber was chosen because it has a much larger diameter than the single mode fiber and is easily identifiable by the imaged end faces of the ferrules 144 and 146. This makes it easier than single-mode fiber
The reference port is easy to find and can be reliably identified. Even if the intensity traverses the core of the fiber 152 and its image adversely affects the procedure for making the ferrules 144 and 146, the above is consistent. The same fiber array or bundle 235 is used for both the input and output ferrules 144 and 146 to provide the fiber bundle 235.
The ferrules are arranged on the opposing surfaces of as shown in FIG.
Thereby, brightness is readily obtained in the core of the fiber 152 by simply pointing the opposing ferrule towards the scattered light source 221. After scanning the image of the ferrule on the computer, the fiber bundle 235 is cut in the middle to separate it into two ferrule assemblies. Fiber bundle 23
5 consists of many single mode fibers and a multimode reference fiber. In the 1 × N optical switch, all but one of the single mode fibers are cut by the input ferrule 144. The measurement alignment station 230, operating under program control, selectively rotates the input and output ferrules of the assembled switch to move the single or multiple fibers 152 of the input optical fiber array 148 to the output optical fibers. Array 150
Align properly with the fiber.

FIGS. 15 and 16 show the alignment of the fibers 152 of the input and output fiber optic arrays 148 and 150 disposed within the input and output ferrules 144 and 146, with each input fiber aligned with the output fiber. The flowchart which calculates | requires an angular coordinate is shown. The first step 245 of this procedure is to place one of the ferrules in a simple fixture after mounting the switch V-groove structure on the microscope 222. For purposes of explanation, output ferrule 146 is described below.

In the next step 246, the ferrule 3
Two images are captured, each image rotated approximately 120 degrees from the position of the previous image. These images are digitized and stored in computer 226 for analysis. For example, the image of the output ferrule 146 is captured in three directions.
Illuminated by 21, the light source of microscope 222 is turned off. The captured image is almost binary, which consists of an illuminated core of fiber 152 on a black background. The binary nature of the image allows the fiber core to be found and searched with relative ease. Typical position errors are on the order of one-half a pixel, or on the microscope 222. With a 5 × objective lens, it is about 1 μm. FIG.
Illuminated fiber 152 at output ferrule 146
Is a reverse image of. The small spot 260 is the illuminated core of single mode fiber and the single large spot 262 is the illuminated core of the multimode reference port or multimode fiber. N ×
The corresponding image of the input ferrule 144 for the N mechanical optical switch 20 is similar to the image of the output ferrule 146. Input ferrule 1 in 1 × N mechanical optical switch 20
The 44 images show a single small spot for a single input fiber. One rotated image of the fiber within the ferrule is used to find the axis of rotation, even if the inside and outside of the ferrule are not concentric. The geometric requirement for the input and output ferrules is that the outer range be substantially circular.

The next two steps 247 and 248 find the coordinates of the center of each fiber and the center of rotation of the ferrule. The alignment procedure analyzes one of the ferrule accumulated images to find the center of each ferrule. This step is
Compare each accumulated pixel to a threshold. Any pixel value greater than this threshold is compared to its eight neighboring pixel values to determine if any of these eight neighboring pixels are greater. If so, let the average center of brightness be the area around the pixel equal to the size of the fiber core. The average center of brightness for each local maximum above the threshold is stored as the coordinates of the fiber 152. The alignment procedure analyzes the ferrule in different directions of rotation to determine the true axis of rotation of the output ferrule 146. The center of the multi-mode reference port 262 in the output ferrule 146 is determined for each of the three images and the following three simultaneous equations are solved to find the center and radius of rotation.

(Equation 4)

(Equation 5)

(Equation 6)

In these equations, (x1, y1),
(X2, y2) and (x3, y3) are the coordinates of the fiber core in the three images, (a, b) are the coordinates of the center of rotation, and r is the radius of rotation. This opening is as follows.

(Equation 7)

(Equation 8)

(Equation 9)

The above equation finds the coordinates of the axis of rotation for the ferrule 146, and the image analysis shows the output fiber array 15
Determine the position of each fiber 152 in the coordinate system of the 0 microscope. Coordinate conversion is performed for each fiber 15 in the output ferrule 146 in the coordinate system searched on the rotation axis of the ferrule.
Find the position of 2. Let xli and yli be the coordinates of the i-th fiber in the standard laboratory frame of reference. Note that xfi and yfi represent positions in a coordinate system centered on the ferrule axis. Both coordinate systems are Cartesian coordinate systems, the x and y axes of which are parallel. The coordinate conversion formula is as follows.

(Equation 10)

[Equation 11] Here, a and b represent the x and y coordinates of the center of the ferrule in the laboratory reference frame of the microscope.

The next step 249 is to place the input ferrule 144 in the fixture of the microscope 22. Acquire three images of the end face of the input ferrule in three different directions of rotation and solve these three simultaneous equations for (a, b) and r. If the mechanical optical switch is an N × N type switch, a multimode reference fiber 262 is used, and if the switch 20 is a 1 × N type switch, a single mode input fiber is used to determine the coordinates of the ferrule axis of rotation. Ask. The tracking radius of multiple input fibers or a single fiber, or the distance from the axis of rotation of the input ferrule 144 to the core of the input fiber is determined.

In the next step 250, the ferrule 14
Calculate the radial coordinates of each fiber core 260 with respect to the center of 6 and the relative change in alignment coordinates for each fiber with respect to the reference fiber 262. Next, the offset distance of the V groove, which is the offset distance of the ferrule, is substantially obtained from the standard of the switch, or directly measured by a microscope. In addition, the rules for positive and negative rotation of the ferrule are defined. Forward rotation is defined as counterclockwise when viewed at the optical interface of either ferrule. Negative rotation is defined as clockwise. The positive x-axis and y-axis have their origin at the center of the output ferrule, the x-axis extends to the right and the y-axis extends to x degrees 90 degrees above. In this arrangement,
When both ferrules are rotated to an equiangular angle within their own coordinate system, they point in opposite directions so that they counter-rotate with the light ink.

The radius of the locus of rotation of each output fiber and the angle during which each fiber is linearly coupled to the x-axis are determined by the following equation (angle is in degrees).

(Equation 12) If xi> 0 and yi> 0 (the point is the first 90 degree range),

(Equation 13) If xi <0 and yi> 0 (the point is the second 90 degree range),

[Equation 14] If xi <0 and yi <0 (the point is the third 90 degree range),

(Equation 15) If xi> 0 and yi <0 (the point is the fourth 90 degree range),

(Equation 16) Performs a further rotational transformation of the output fiber coordinates, so
Position the multimode reference fiber or port on the positive x-axis. X-of all output single mode fibers
The y coordinate is calculated in this new reference frame. The same procedure is used for the input fiber in NxN mechanical optical switches.

The next step, step 251 is to calculate the relative switch coordinates from the reference multimode port using the estimated ferrule offset. FIG. 18 shows the alignment for any input fiber. The distance between the centers of two ferrules is V if the ferrules have the same outer diameter.
The groove offset d. Ferrules with unequal diameters may be used without departing from the spirit of the invention. Point 2
64 and 265 are the center of the output ferrule and the center of the input ferrule, respectively. Point 266 is the point where the closed curve of the input fiber intersects the output fiber. From the geometry of the triangle, we have

[Equation 17]

(Equation 18) Solving equations 17 and 18,

[Equation 19]

(Equation 20) Equations 19 and 20 give the alignment conditions for each fiber with respect to the positive x-axis. Since each fiber polar coordinate is known, the alignment coordinates for each fiber can be calculated relative to the alignment coordinates of any other fiber. The relative switch coordinates are passed to the measurement alignment station 230, where they are computer 234.
And is used as a starting point to bring the alignment of multiple input fibers or a single input fiber to the output fiber to a peak (peaking).

As mentioned above, the fiber bundle 235 includes input and output ferrules 144 and 146 located at each end.
, Including single mode fiber and multimode reference fiber,
After the step, it is cut in half. The ferrule is fixed in the mounting member of the mechanical optical switch 20 and connected to the drive motor of the switch 20. Connect the assembled switch to the measurement alignment station 230 in step 252,
Laser source 231 is coupled to input single mode fiber 235 as shown in FIG. Single mode
Fiber bundle 236 and reference fiber 237 are connected to power meters 232 and 233, respectively. Power meter control cables 238 and 239 connect these power meters to computer 234. The switch control cable 240 connects the optical switch 20 to the computer 234. Step 252 aligns to the multimode reference port, fiber input single mode fiber, using a blind search routine (blind alignment algorithm) as shown in FIG.

Assemble the input and output ferrules 144 and 146 in the mechanical optical switch 20, ignoring the position of the input fiber to the home position sensor (photodetector) 52 of the switch 20 and the reference port 262. The initial power-up of the mechanical optical switch 20 causes the drive motor 4
6 couples each ferrule rotation to the home position defined by sensor 52. In this regard, the blind search routines are called Home-Away-From (Home-Away-From
-Home: Initialized to the position of HAH. This position is 180 degrees from the home position. This routine speeds the search when the operator manually controls the motor to rotate to the positions of the input single mode fiber and the reference fiber within the same 90 degrees. When the blind search routine starts, the input ferrule 144 and the output ferrule 146 will be at any start position (ASP) or HA.
It is in the H position (step 270). Although the degree of rotation at each step is shown below in this blind search routine, some steps may be adjusted as an empirical instruction. Further, the degree of rotation is a function of the number of single mode fibers in the output ferrule 146. Also, although this routine refers to the degree of rotation, the actual data saved for the angular coordinates of the aligned fibers is in the motor step. At step 271, the output ferrule is rotated for 5 to 15 degrees of rotation, and at step 272 the output optical power from the reference fiber is measured and compared to a threshold. The optical power output does not exceed the threshold value, and the output ferrule rotates 3 times from the ASP or HAM position in step 273.
If it is not over 60 degrees, the routine returns to step 271 to rotate the output ferrule another 5 to 15 degrees. If the rotation of the output ferrule exceeds 360 degrees, as shown in step 274, the output ferrule is reset to the ASP or HAH position, the input ferrule is rotated by 5 to 15 degrees, and output in step 271. Rotate the ferrule again 5 to 15 degrees. Until the output power measured by the optical power meter exceeds the threshold,
Rotate the input and output ferrules, step 275
Then, the peaking routine (algorithm) is executed.

The peaking routine shown in FIGS. 20 and 21 defines the input ferrule as 1 and the clockwise direction as 1 as shown in steps 281 and 282.
Start. At step 283, the current stepper motor coordinates are defined as the best coordinates. The assumption is that there is light coupling from the input fiber to the output fiber. As shown in step 284, the current stepper
Initialize this routine by defining the motor coordinates as the final (ie, latest) best coordinates and setting the variable N to zero. This routine initializes the ferrule to minus one and the rotation to minus one in step 285. That is, the output ferrule is rotated counterclockwise in the first peaking pass. The routine starts by rotating the output ferrule counterclockwise to determine the coordinates of the maximum amount of optical power coupled from the input fiber to the output fiber. Save this coordinate as the best coordinate. These steps are shown in steps 286-289. This routine passes the best coordinate for more than two steps in step 290, and sets N to 1 and rotation to minus 1 in steps 291 and 292 to rotate the output ferrule clockwise. . This routine finds the coordinates of the maximum optical power coupled into the output fiber during the clockwise rotation of the output ferrule, saves these coordinates as the best coordinates, and repeats steps 286-289. If N equals 1, the routine returns to step 29.
Proceed to the best coordinate at 3 and compare this best coordinate with the final best coordinate at step 294. If they are not the same on both motors, the routine returns to steps 283 and 28.
Returning to 4, redefine the current stepper motor coordinates as the best coordinates, redefine the current stepper motor coordinates to the final best coordinates, and reset N to 1. What changed in coordinates are the stepper motor coordinates of the output ferrule. In step 285, the ferrule is set to positive 1 (-1
X-1 = 1) to switch this routine to an input ferrule. Rotate the input ferrule both counterclockwise and clockwise to find the best coordinates for the input ferrule and repeat steps 286-292. After finding the best coordinates for the input ferrule, this routine
At step 294, the best coordinates are compared to the final best coordinates to determine if they are equal on both motors. If the result is yes, this routine returns to step 295.
Then, it is determined whether both motors circulate (repeated). If the result is yes, then in step 296 the best coordinates are saved as the optimum alignment position for the input fiber and the selected output fiber. Then this routine
Return to the blind search routine, i.e., the calling routine. The blind search routine then returns to the alignment routine. The number of steps from the home position of each stepper motor to the alignment point is saved as the intersection coordinates.

The alignment routine proceeds to step 253 where the first
Moving to the coordinates for port number 2 which is a single mode fiber, the peaking routine described above is used to find the appropriate coordinates for maximum light throughput from the input fiber to the output fiber. This routine returns to step 254.
Then, using the alignment data from port 2,
Recalculate the offset. Equation 19 gives θ1 as a function of r, d and R. θ1 is not known, but θ1
Is a function that aligns port 2 using the peaking routine. The change in θ1 is the difference between the calculated angular coordinate for port 2 and the aligned coordinate found using the peaking routine. Error is offset d
It is assumed that the correction factor for this offset can be estimated using the derivative of Eq. Using this correction factor, the value of offset d can be changed and new alignment coordinates can be recalculated for the fiber. The change of alignment coordinates
Perform this procedure each time you align a new port until it is below a certain preset threshold.

When the derivative of equation 15 with respect to d is obtained, rearranged, and the difference in delta is given, the following equation is obtained.

(Equation 21)

(Equation 22) The routine proceeds to the calculated coordinates for port 3 at step 255 and uses the peaking routine to align the port with the input fiber. The routine recalculates the ferrule offset using the port 3 aligned coordinates in step 256 and the relative aligned coordinates for all other ports relative to port 3. This routine
At step 257, proceed to the next port and each subsequent port to align the fiber using a peaking routine. At step 258, each time the port is aligned, the routine determines if it is the last port. When the final port is aligned, then in step 259 the routine stops. The best coordinates stored for each of the aligned ports are read and stored in the switch memory circuit. The switch 20 is now ready for use.

As mentioned above, the mechanical optical switch of the present invention can be configured with any number of input and output fibers, or ports. The basic operation of this switch is, at an intersection coincident with the intersection of the second optical fiber, in response to the angular coordinates representing the position of the fiber, at one of the two intersections on the closed curve, on the closed curve. The input, ie the first fiber, is rotated. In response to the angular coordinates representing the position of the second fiber at the intersection, the output, ie the second fiber, is rotated on its closed curve to the intersection corresponding to the intersection of the first fiber. These rotational movements can be performed continuously,
In the preferred embodiment, these can be done simultaneously.
Since the offset closed curve intersects at two unique points, one can choose the intersection closest to the input and output fibers before rotating the fiber to increase the switch speed.

Tests have shown that when one ferrule spins in the same sense as another, one ferrule moves the other after the other ferrule stops spinning. To solve this problem, each fiber is rotated an equal amount past the selected intersection, both are rotated counterclockwise simultaneously and stopped at the intersection at the same time. Tests have also shown that one or both of the input or output rotating parts of the switch continuously rotate their drive lines until the fiber breaks or the motor stalls. The switch is configured such that an interrupt signal is generated when any of the motors drives the drive line assembly by more than one or one and one half times from each home position. A reflector or perforated rotating plate attached to each drive line assembly allows light to pass to each detector at the home position. If this happens and the motor stops,
User error code occurs.

An invalid fiber or port request can be issued to the switch. For this reason, each input and output fiber or port selection is valid before the input or output portion of the switch is rotated. Maximum limits are set for the input and output sections based on the number of fibers in each section. When the fiber or port demand exceeds the maximum limit, a user error code is generated and these parts are quiesced.

In switch configurations in which the input and output sections are multiple fibers, or ports, individual fibers are selected for either the input or output section before rotating these sections. When selecting a new fiber or port for maximum fiber position or port position,
It is possible to exceed. To prevent this condition from destroying the switch, the angular coordinates of the new selected fiber or port to the intersection are added to the angular coordinates of the previously selected fiber or port intersection. The added angle coordinate value is compared with the maximum range value, and when the added angle coordinate exceeds the maximum range value, a user error code is generated. The angular coordinates in the preferred embodiment are stored for each stepper motor step.

FIG. 22 shows a perspective view of a mechanical fiber optic switch 300 improved by the present invention. The switch 300 comprises a housing 302 having a base 303, end walls 304, 306 and side walls 308, 310 and forming a cavity 312. Within cavity 312 is provided a central pedestal 314 similar to pedestal 34 of FIG. A holder structure similar to the holder structure of FIG. 7 is formed in the pedestal 314. The holder assembly includes an offset V-groove and a spring clamp (spring clamp), and the mounting member 350.
(FIG. 23) is retained. A recess (316) is formed on the top of the housing 302 and a gasket (not shown) is formed.
Receive. The gasket is fixed to the recess 316 by the upper surface (not shown). This top surface is similar to the top surface 40 of FIG. Similar to the switch 20 of FIG. 1, a circuit board (not shown) having an electronic circuit is attached to the switch housing 3.
Install on 02. Cavity 314 is surrounded by the top surface and is filled with a suitable index matching liquid to provide input fiber 31
5 and the return reflection of the input light passing through the output fiber 317.

Drive motors 318 and 320, such as stepper motors or DC motors with encoders, are secured to the sidewalls 310 by motor clamps 322 and 324.
Gear clamps 326 and 328 are spur gears 330 and 3 respectively.
32 is fixed to the shafts of drive motors 318 and 320. Holes (bore) 334 and 336 (hole 336 is visible)
Are formed in each end wall 304 and 306 to receive mounting member drive line assemblies 338 and 340. Base 303
Attached to is the detection brackets 342 and 344, to which the reflection sensors 346 and 348 are attached. These reflective sensors may be HOA1160 manufactured by Honeywell of Minneapolis, Minn., USA.

The housing 302, top surface, motor clamp and sense clamp may be made of the same material as the housing 22 of FIG. In the improved design, these parts are machined or formed aluminum. Drive motors 318 and 320 are stepper motors such as the Model 33755-01 from HTS I Inc., Watterbury, Conn., USA. The gear clamps 326 and 328 used in the current design are CG1-25-A manufactured by W. M. Berg Co., East Rockway, NY, USA. The spur gears are model H47-72 manufactured by Piracy Precision Industrial Components, Inc., Middlebury, Connecticut, USA.

FIG. 23 shows opposing mounting members and two similarly designed mounting member drive lines 338 and 3.
It is a top view with one of 40. The mounting member drive line has a mounting member 350, such as a ferrule, having an end coupled to a strain relief coupler 352. The other end of the mounting member 350 is a sleeve member 354 fixed thereto, the purpose of which will be described later in detail. To the other end of strain relief coupler 352 is coupled a flexible drive shaft coupler 356, such as the FC-1 Flexible Bellows from Servometer, Cedar Grove, NJ, USA. For use in a mechanical fiber optic switch of this design, a bellows stock coupler is placed to widen the inner hole. One end of the flexible drive shaft coupler 356 has a strain relief coupler 352.
At one end and the other end on the drive shaft 358. The drive shaft is a stainless steel component and is used by Piracy Inc., Middlebury, Connecticut, USA.
It is either Precision Industrial Component's A3-23 type or Double M-Berg's S4-23 type of East Rockway, NY, USA. A retaining ring 360 is mounted on the drive shaft 358, which is a W. M. Q7.
-25 type. Retaining ring 3 on drive shaft 358
Install the inner race ring 360 next to 60,
This is an SS2-32 type manufactured by W. M. Berg. The bearings 364 and 366 such as type B1-31-Q3 manufactured by W.M.B.
Attached next to spacer 362 above. Positioned between the bearings 364 and 366 is a bearing spacer 368, such as the SS-65 model from Double M. Berg. On the drive shaft 358 near the bearing 366, an outer race spacer 370 such as a W.M.B.SS3-13 type is provided, followed by a W.M.B.Q4-50 type. Another release ring 372 is provided. R315LB-2 made by Val Seal Engineering of Santa Ana, California, USA
A seal 374 such as 02-SP-45 releases the ring 37
Position near 2. The end of the seal 374 opposite the release ring 372 has a flange 376 which fits within a recess formed in the outer surface of the end walls 304 and 306 and surrounds the openings 334 and 336. The seal cover 378 and outer race spacer 380 seal 37
Position with respect to 4. The seal cover and outer race spacer 380 have coextensive openings formed therein to receive screws or the like. The seal cover 378 and the outer race spacer 380 are attached to the end wall 30.
4 and 306, and the seal 374 is fixed to the housing 302 with screws. Outer race spacer 38
On the drive shaft 358 in the vicinity of 0, there is a bearing 382 such as a model of B1-31-Q3 manufactured by W. M. Berg.
And another inner race spacer 384, such as the SS2-30 model from Double M. Berg. Gear 330
, 332 and a spur gear 386 similar to drive shaft 35
8 and fixed there with a gear clamp 388 similar to gear clamps 326 and 328. A reflector cord wheel 390 is attached to the end of the drive shaft 358 in line with one of the reflection sensors 346 and 348. The improved and simplified drive line has a reduced number of coupling joints compared to the drive lines of FIGS. Furthermore, all couplers are TRA Bond BA-F2.
Either glued together with an epoxy such as 30 epoxy or Epo Tech 253ND epoxy, or clamped in place with a split hub releaser.

As described above with respect to mounting member ferrule 86, mounting member ferrule 350 may be formed of borosilicate glass. Expanded testing of the mechanical fiber optic switch of the present invention showed that glass ferrule 35
It was found that the 0 end faces wear together. At times, the fibers are contaminated with wear particles. This problem appears gradually, but sometimes it is irregular and increases in the insertion loss of the switch. The cross-sectional view of FIG. 24 along line AA ′ of FIG. 23 shows how a ceramic sleeve 354 was used to solve this problem. A ceramic sleeve 354, such as that made by Mine Drum Precision Products, Inc., Rancho Cucamonga, CA, is glued to the end of glass ferrule 350 with epoxy. The ferrule arranged with the optical fiber and the sleeve 354 are finished as a monolithic part. This is polished more slowly, as ceramic is much harder than glass. As a result, the lower rubbing surface 392 is formed, and the surface of the glass is roughly 11 to 15 μm, which is smaller than the ceramic surface. Therefore, as shown in FIG. 24, the glass ferrule is not strong at all. The ceramic sleeve separates the ferrules by about 25 μm. In addition, ceramic wear is better than glass, so few wear particles cause contamination problems.
Instead of using a ceramic sleeve with a glass ferrule, replace this glass sleeve with a ceramic ferrule. Such a ceramic ferrule is, for example, manufactured by Riquey of America, Inc. of Cupentino, California, USA. With ceramic ferrules, there is less rubbing of the fiber, but this has the advantage that insertion error can be slightly reduced due to less longitudinal alignment error. The preferred material used to form the ceramic sleeve 354 and ceramic ferrule has a burst strength of 8 MPa * m ^.
It is (1/2) zirconium oxide.

Another problem found during expansion testing of the mechanical fiber optic switch of the present invention is that the ferrule quickly and differentially wears in the V-groove, causing the switch to be out of alignment. This problem manifests itself as a progressive increase in loss, sometimes accentuated by the changing shape of the insertion loss. A solution to this problem is to line the V-groove and spring fasteners and composite zirconium oxide wear resistant ceramic inserts into the ceramic sleeve 364 and ferrule 350. Sapphire inserts for use with glass ferrules may be used to solve this problem.

Another problem is to bond the wear resistant crystal insert to the V-groove. A tough, sturdy adhesive such as an epoxy resin bends the insert. To prevent the epoxy resin from bending the insert, increase the thickness of the insert to 0.062 inches (about 1.57 mm). This greatly reduces the amount of bending.

In another embodiment of the mechanical optical switch 20,
A photodiode is added in switch 20 near the interface between input and output fiber arrays 148 and 150. Photodiode array 14
The amount of light diffused near the optical interface between 8 and 150 is monitored and an electrical output is generated in relation to the placement error of the different ports of switch 20. The minimum electrical signal from the photodiode indicates the maximum alignment between the selected input and output ports. Including a photodiode in the mechanical optical switch 20 allows active alignment of the ports after it has been used. This extends the useful life of the switch 20.

Aligning the ports of switch 20 allows switch 20 to be used in remote fiber test equipment.
Such a device is part of a telecommunications company's central office system, as is typically shown in FIG. The central office 400 has a central office switch 402 coupled to fiber optic links 404, 406 and 408, which are the other central offices within remote central offices 416, 418 and 420.
Connected to switches 410, 412 and 414. The fiber optic links 404, 406 and 408 comprise optical transmission fibers for optical communication and optical test fibers referred to in the industry as "dark fibers." The optical switch 422 of the present invention is coupled to the central office switch 402 as part of a remote fiber test system. This test system consists of an optical time domain reflectometer (OTDR), optical power meter, SDH / SO coupled to the input port of switch 422, ie fiber.
It includes a single measurement test instrument 424, such as a NET test set. The output fiber or port of switch 422 is coupled to fiber optic links 404, 406 and 408 via optical couplers 426, 428 and 430. These combiners 426, 428 and 430 may be wavelength division multiplexers (WDM).

In one application, WDM4
26, 428 and 430 through fiber optic links 404,
Coupled to the "dark fiber" in 406 and 408,
Let the measurement test equipment 424 be OTDR. Central office
The computer passes commands to the switch 20 via the bus to connect a particular input port to a particular output port. Electronic circuitry on the switch 20 interprets this command to access the stored coordinate position for the selected ports and rotate each port to the intersection on the closed curve of those ports. Send a command to the optical switch 422,
A specific output fiber, or port, can be
To the input fiber or port coupled to the. For example, switch the output port 1 of the switch 424 to the WDM 426
May be coupled to the “dark fiber” of fiber optic link 404 via. The OTDR 424 fires a light pulse into a "dark fiber". The return reflected light scattering signal is transmitted through the WDM 426 and the optical switch 422 to the OT.
It binds to DR424. The OTDR 424 processes this return optical signal to generate an indication or table indicating the presence of fiber anomalies such as reflections and losses. Additional commands can be sent to the optical switch 422 to align other output fibers or ports with input fibers or ports to test other "dark fibers" in other optical links. In addition, an additional set of measurement and test equipment may be added to the optical switch 42.
It may be coupled to two additional input fibers or ports.

It is also possible to connect the output fiber of the optical switch, that is, the port, to the optical communication fiber of the optical link via the WDM connected to these fibers. OT
When testing active transmission fiber by DR
The wavelength of the optical output of the TDR 424 differs from the wavelength of active optical transmission over the transmission fiber. For example, if the transmission link is operating at 1310 nm wavelength,
The OTDR 424 operates at 1550 nm to test the transmission fiber of the link. While running these tests,
Active transmission is performed in the fiber.

Another application for remote fiber test systems is to test SDH / SONET performance using the SDH / SONET test set. Such a test set has a transmitter at one end and a receiver at the other end. As an example, the input fiber or port of the optical switch 422 may be the OT at the central office 400.
It is coupled to SDH / SONET transmitting equipment instead of DR. Central office 416 has SDH / SONET receiver equipment 432 coupled to the input fiber, or port, of optical switch 434. The output port of the optical switch is W
It is connected to the optical link 404 via the DM 436. Commands are sent to the optical switches 422 and 434 to couple their input and output ports to one another through one of the optical transmission fibers in the optical link 404 to SDH / SONET transmitter and receiver equipment. Each optical transmission fiber of the optical link can be coupled via WDM to each output fiber, or port, of the optical switch to perform SDH / SONET testing of all transmission fibers in this link.

The mechanical optical switch 20 of the present invention provides input and output optical fiber arrays 148 and 150 that represent the input and output optical ports in the switch to align input and output optical fibers 152. It has been described using an electric stepper motor 46 that rotates the output ferrules 144 and 146. It is also possible to implement the invention using manual means to align the input and output ports. With such a switch, the stepper motor 46 and spur gear 48 may be replaced by a reduction gear assembly. Such a reduction gear assembly engages the ferrule drive shaft spur gear 72 on the ferrule drive shaft 62. The knob manually turns the gear assembly, which in turn causes the switch 2
Provided to rotate ferrules 144 and 146 in 0. A detent is provided with the gear assembly to indicate the aligned position of the input and output ports. Alternatively, the alignment may be done by monitoring the appropriate output port for the maximum optical signal.

Mechanical optical switches have cycle-cycle repeatability,
Meets long-term repeatability and absolute placement error specifications. This switch has a low manufacturing cost and is simple to manufacture. The switch has offset ferrules that rotate about independent axes, with ferrules held independently in separate three-point kinematically accurate tables, such as V-blocks. The V-block is lined with an abrasion resistant material such as glass or ceramic and lubricated with an index matching liquid. By displacing the ferrules from each other and then mounting on a kinematically accurate table, the fiber held in the ferrule tracks a closed curve with the closed curve of the fiber in the input ferrule that intersects the closed curve of the fiber in the output ferrule I do. The input and output ferrules are fully loaded with fibers, and all fibers are accessible as ports, except for fibers centered on the axis of the ferrule. further,
Ceramic sleeves can be used to reduce wear at the optical interface, thereby reducing insertion loss over time between the input and output fibers. The optical switch can also be used in remote test systems and optical metrology test equipment can be used to perform tests on fiber optic links. The above and other concepts of the invention are set forth in the following claims.

[0085]

According to the optical switch of the present invention, an optical switch for an optical fiber which satisfies the specifications of cycle-to-cycle repeatability, long-term repeatability and absolute alignment error and is inexpensive and simple to manufacture is obtained. Further, the alignment between the input fiber and the output fiber can be surely performed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a mechanical optical switch according to the present invention.

FIG. 2 is a diagram showing an ideal state and an actual state in coaxial alignment of a conventional mechanical fiber optical switch.

FIG. 3 is a side view of a conventional mechanical fiber optic switch.

FIG. 4 is a perspective view of a ferrule driving structure in a mechanical optical switch according to the present invention.

FIG. 5 is an exploded perspective view of a ferrule driving structure in the mechanical optical switch according to the present invention.

FIG. 6 is a diagram showing a ferrule shift in the mechanical optical switch according to the present invention.

FIG. 7 is a plan view showing a kinematically accurate holder structure in a mechanical optical switch according to the present invention.

FIG. 8 is a simplified perspective view showing a staggered input ferrule and output ferrule of a mechanical optical switch according to the present invention.

FIG. 9 illustrates an exemplary alignment fixture for aligning an input port optical fiber with an output port optical fiber in a mechanical optical switch according to the present invention.

FIG. 10 is a portion of an exemplary flow chart illustrating a procedure for aligning an input port optical fiber with an output port optical fiber in a mechanical optical switch according to the present invention.

FIG. 11 is another part of an exemplary flow chart illustrating a procedure for aligning an input port optical fiber with an output port optical fiber in a mechanical optical switch according to the present invention.

FIG. 12 is a graph showing a mathematical model for coupling between two optical fibers having an alignment error used in a procedure for aligning optical ports in a mechanical optical switch according to the present invention.

FIG. 13 shows an analysis station of an alignment device used to calibrate a mechanical optical switch according to the present invention.

FIG. 14 shows a mechanical alignment station of an alignment device used to calibrate a mechanical optical switch according to the present invention.

FIG. 15 is a part of a flowchart of a procedure for obtaining the angular coordinates of the intersection of the optical fibers facing each other of the input port and the output port in the mechanical optical switch according to the present invention.

FIG. 16 is another part of the flowchart of the procedure for obtaining the angular coordinates of the intersection of the optical fibers facing each other of the input port and the output port in the mechanical optical switch according to the present invention.

FIG. 17 is a diagram showing an inverted image of the output fiber of the output ferrule in the mechanical optical switch according to the present invention.

FIG. 18 is a diagram showing an alignment state of arbitrary input fibers in the mechanical optical switch according to the present invention.

FIG. 19 is a flow chart of a blind search routine for finding a reference fiber in a mechanical optical switch according to the present invention.

FIG. 20 is part of a diagram illustrating a peaking routine for optimizing the alignment of opposing fibers at input and output ports and returning their angular coordinates in a mechanical optical switch according to the present invention.

FIG. 21 is another part of the figure while in a mechanical optical switch according to the present invention, a peaking routine that optimizes the alignment of opposing fibers at the input and output ports and returns their angular coordinates.

FIG. 22 is a perspective view of an improved mechanical optical switch according to the present invention.

FIG. 23 is a plan view of a mounting member drive line assembly of an improved mechanical optical switch according to the present invention.

FIG. 24 is a cross-sectional view of the mounting member of the improved mechanical optical switch according to the present invention, taken along line AA ′ in FIG. 23.

FIG. 25 is a simplified diagram of a remote fiber test system using a mechanical optical switch according to the present invention.

[Explanation of symbols]

 20 Optical Switch 22 Housing 24 Base 26, 28 End Wall 34 Center Stand 38 Detachable Side Wall 40 Top Plate 42 Circuit Board 46 Rotation Drive Means 48 Spur Gear 50 Photo Detector Fixture 52 Photo Detector 56, 58 Bearing 60 seal plate 62 ferrule drive shaft 66, 67 optical fiber 68 holed rotating body 70 slot 72 ferrule drive shaft spur gear 74 flexible drive shaft coupler 76 spring fastener 80 input portion 82 output portion 86 tubular holding member 100, 102 Ferrule 108, 110 Optical fiber 112, 114 Closed curve 120 Offset holder structure 122 V-groove structure 126, 128 Side wall 130 V-groove cavity 132, 134 Abrasion resistant flakes 140, 142 V-groove 144, 146 Ferrule 148 Input optical fiber Array 150 Optical fiber array 152 Optical transmission line 160 Control means 220 Analysis station 221 Scattering light source 222 Microscope 224 Video monitor 230 Measurement alignment station 231 Laser source 232, 233 Power meter 235 Input single mode fiber 236 Single mode fiber Bundle 237 Reference fiber 260 Fiber core 262 Multimode reference fiber 300 Optical switch 315 Input fiber 317 Output fiber 338, 340 Mounting member drive line 350 Ferrule 354 Sleeve member 356 Flexible drive shaft coupler 422, 434 Optical switch

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Steve Yu Rainhold, Oregon, USA 97756 Redmond Rimrock Way 244 Namba 7 (72) Inventor Lorimar El Twig, Oregon, USA 97759 Cisters Vogt Horn 17478 (72) Inventor Mark Dee Marineau USA Oregon 97756 Redmond North West Rimrock 1209

Claims (36)

[Claims] 1. At least one first optical fiber disposed in a first ferrule rotating about an independent first axis of rotation and moving on a first closed curve, and independently from the first axis of rotation. Is disposed in a second ferrule that rotates about a second rotation axis that is deviated from, and moves on a second closed curve having an intersection with the first closed curve deviating from the first closed curve and facing the first optical fiber Relationship between at least one second optical fiber forming the optical interface, and the optical interface holding the first and second ferrules, respectively, and being stiffer than the ferrule and the optical fiber, The first and second sleeve members forming a V-shaped cavity by the first and second sleeve members, which rub against the ferrule to form open end face regions, respectively, and the top and angularly widened side walls. Kinematics V to receive each
A groove assembly, each including spring fasteners having first and second spring fastener members disposed over the V-shaped cavity to retain the ferrule within the cavity, the sidewall of the V-groove assembly and the spring. First and second offset holder assemblies having fasteners secured to the sidewalls of the V-groove assembly and the spring fasteners and having wear resistant inserts having a hardness greater than or equal to the ferrule; and the closed curve of the first optical fiber and Means for accumulating angular coordinates representing the intersection between the closed curves of the second optical fiber, and selectively rotating the first and second optical fibers in relative relation to each other about respective independently staggered axes of rotation. Let me
An optical switch comprising means for axially aligning the first and second optical fibers at one of the intersections on the closed curve. 2. The optical fiber further comprises a plurality of optical fibers arranged in the second ferrule, the plurality of optical fibers rotating about the independent second rotation axis and arranged in the second ferrule. The optical switch according to claim 1, wherein at least one cross point is formed between each of the closed curves of the plurality of optical fibers and the closed curves of the optical fibers disposed in the first ferrule. . 3. The optical switch according to claim 2, wherein the plurality of optical fibers completely fills the second ferrule. 4. The optical fiber further comprises a plurality of optical fibers arranged in the first ferrule, the plurality of optical fibers being rotated about the independent first rotation axis and arranged in the first ferrule. 2. An optical switch according to claim 1, wherein at least one cross point is formed between each of the closed curves of the plurality of optical fibers that have been closed and the closed curve of the optical fibers that are arranged in the second ferrule. . 5. The optical switch according to claim 4, wherein the plurality of optical fibers in the first ferrule completely fill the first ferrule. 6. The apparatus further comprises a plurality of first optical fibers and a plurality of second optical fibers arranged in the first and second ferrules, respectively, wherein the plurality of first optical fibers are the independent first rotations. A plurality of closed curves of the plurality of first optical fibers disposed within the first ferrule, the plurality of second optical fibers rotating about an axis and the plurality of second optical fibers rotating about the independent second rotation axis. The optical switch according to claim 1, wherein at least one intersection is formed between the closed curves of the second optical fibers arranged in the second ferrule. 7. The plurality of first ferrules in the first ferrule.
An optical fiber and the plurality of second ferrules in the second ferrule
7. The optical switch according to claim 6, wherein an optical fiber completely fills each of the first and second ferrules. 8. The V-groove insert has wear resistant flakes adhered to opposite ends of the sidewalls, the first and second V-groove inserts comprising:
The optical switch of claim 1, wherein a double end bearing for a ferrule is formed. 9. The first and second spring fastener members are disposed on respective bearings of the double end bearing to house the first and second ferrules in the V-shaped cavity. The optical switch according to claim 8. 10. The optical switch of claim 1, wherein the first and second ferrules comprise a borosilicate material. 11. The optical switch of claim 1, wherein the first and second sleeve members comprise a ceramic material. 12. The optical switch of claim 11, wherein the ceramic material comprises zirconium oxide. 13. The optical switch of claim 1, wherein the wear resistant V-groove insert and the wear resistant spring insert comprise sapphire. 14. The first and second sleeve members, the wear resistant V-groove insert and the wear resistant spring insert comprise a ceramic material.
Light switch. 15. The optical switch of claim 14, wherein the ceramic material comprises zirconium oxide. 16. The rotating means is responsive to one angular coordinate of the intersection of the first and second closed curves to rotate the first and second optical fibers to couple the first and second optical fibers.
The optical switch of claim 1, further comprising a second stepper motor. 17. The high resolution encoder coupled to rotate the first and second optical fibers in response to one angular coordinate of the intersection of the first and second closed curves. 2. The optical switch according to claim 1, further comprising first and second DC motors having a. 18. The rotating means includes a rotatable shaft coupled to each of the ferrules, each rotatable shaft engaging a first spur gear mounted on the rotating means. The optical switch according to claim 1, further comprising two spur gears. 19. The optical switch of claim 18, wherein the first and second bearings have a central hole for receiving each rotatable shaft. 20. Each of the rotatable shafts is coupled to a first shaft having a central bore for receiving one of the first and second optical fibers, and connecting the first shaft to a corresponding ferrule. 20. The optical switch of claim 19, comprising a flexible drive shaft. 21. A first ferrule that rotates about an independent first axis of rotation and is stiffer than an optical fiber;
At least one first optical fiber that moves on a closed curve and rubs against the ferrule to form an open end surface region, and independently rotates around a second rotation axis that is laterally displaced from the first rotation axis Is located in the rigid second ferrule, is displaced from the first closed curve and moves on a second closed curve having an intersection with the first closed curve, forms a rubbing release end face region on the ferrule, and forms the first optical fiber with the first optical fiber. At least one second optical fiber forming an optical interface in the rubbing release endface region of the ferrule in opposed relation, and a V-shaped cavity formed by the top and angularly widened sidewalls Kinematic V
A groove assembly, each including spring fasteners having first and second spring fastener members disposed over the V-shaped cavity to retain the ferrule within the cavity, the sidewall of the V-groove assembly and the spring. First and second offset holder assemblies having fasteners secured to the sidewalls of the V-groove assembly and the spring fasteners and having wear resistant inserts having a hardness greater than or equal to the ferrule; and the closed curve of the first optical fiber and Means for accumulating angular coordinates representing the intersection between the closed curves of the second optical fiber, and selectively rotating the first and second optical fibers in relative relation to each other about respective independently staggered axes of rotation. Let me
An optical switch comprising means for axially aligning the first and second optical fibers at one of the intersections on the closed curve. 22. The optical fiber further comprises a plurality of optical fibers arranged in the second ferrule, the plurality of optical fibers rotating around the independent second rotation axis and arranged in the second ferrule. 22. The optical switch of claim 21, wherein at least one cross point is formed between each of the closed curves of the plurality of optical fibers that have been closed and the closed curve of the optical fibers that are disposed in the first ferrule. . 23. The optical switch of claim 22, wherein the plurality of optical fibers completely fills the second ferrule. 24. Further comprising a plurality of optical fibers disposed within said first ferrule, said plurality of optical fibers being rotatable about said independent first axis of rotation and disposed within said first ferrule. 22. The optical switch of claim 21, wherein at least one cross point is formed between each of the closed curves of the plurality of optical fibers that have been closed and the closed curve of the optical fibers that are disposed in the second ferrule. . 25. The optical switch of claim 24, wherein the plurality of optical fibers in the first ferrule completely fill the first ferrule. 26. The apparatus further comprises a plurality of first optical fibers and a plurality of second optical fibers arranged in the first and second ferrules, respectively, wherein the plurality of first optical fibers are the independent first rotations. A plurality of closed curves of the plurality of first optical fibers disposed within the first ferrule, the plurality of second optical fibers rotating about an axis and the plurality of second optical fibers rotating about the independent second rotation axis. 22. The optical switch according to claim 21, wherein at least one intersection is formed between the closed curves of the second optical fibers arranged in the second ferrule. 27. The first optical fibers in the first ferrule and the second optical fibers in the second ferrule completely fill the first and second ferrules, respectively. The optical switch according to claim 26. 28. The V-groove insert has wear resistant flakes bonded to opposite ends of the sidewalls to form a double end bearing for the first and second ferrules. The optical switch according to claim 21. 29. The first and second spring fastener members include:
The first end of each of the double end bearings is disposed on each bearing.
29. The optical switch according to claim 28, wherein the second ferrule is housed in the V-shaped cavity. 30. The first and second ferrules, the wear resistant V-groove insert and the wear resistant spring insert,
22. The optical switch according to claim 21, comprising a ceramic material. 31. The optical switch of claim 30, wherein the ceramic material comprises zirconium oxide. 32. The rotating means is responsive to one angular coordinate of the intersection of the first and second closed curves to rotate the first and second optical fibers to couple the first and second optical fibers.
22. The optical switch of claim 21, further comprising a second stepper motor. 33. The high resolution encoder coupled to rotate the first and second optical fibers in response to an angular coordinate of one of the intersections of the first and second closed curves. 22. The optical switch of claim 21, comprising first and second DC motors having a. 34. The rotating means includes rotatable shafts coupled to each of the ferrules, each rotatable shaft engaging a first spur gear mounted on the rotating means. 22. The optical switch according to claim 21, having two spur gears. 35. The optical switch of claim 34, wherein the first and second bearings have a central hole for receiving each rotatable shaft. 36. Each of the rotatable shafts is coupled to connect a first shaft having a central bore for receiving one of the first and second optical fibers to the corresponding ferrule. The optical switch of claim 35, further comprising a flexible drive shaft.