WO1991002272A1

WO1991002272A1 - Apparatus for positioning the center of an optical fiber along a predetermined reference axis

Info

Publication number: WO1991002272A1
Application number: PCT/US1990/003905
Authority: WO
Inventors: Melvin Harry Johnson; Jerald Dana Lee; Frank Marsden Willis
Original assignee: E.I. Du Pont De Nemours And Company
Priority date: 1989-08-02
Filing date: 1990-07-17
Publication date: 1991-02-21
Also published as: AU6042090A; EP0485415A1; JPH05500117A; AU649620B2; IE902780A1; EP0485415A4; KR920704166A

Abstract

A positioning apparatus (20) for positioning a point on a cylindrical member having a small diameter, such as an optical fiber (F), along a predetermined reference axis regardless of the outer diameter of the fiber.

Description

TITLE

APPARATUS FOR POSITIONING THE CENTER OF AN OPTICAL FIBER ALONG A PREDETERMINED REFERENCE AXIS

CROSS REFERENCE TO RELATED APPLICATION

Subject matter disclosed herein is disclosed and claimed in copending application Serial Number 07/ 388, 548 _ fjj_ecj contemporaneously herewith, titled "Oplo-Electrσnic Component Having Positioned Optical Fiber Associated Therewith".

BACKGROUND OF THE INVENTION

Field Of The Invention The present invention relates to a positioning apparatus for positioning the center of an optical fiber or other small dimensioned cylindrical member, such as ' capillary tubing, along a predetermined reference axis independently of variations in the outside diameter of the member.

Description Of The Prior Art Devices are known for positioning an optical fiber so that the axis of the fiber is positioned with respect to a reference axis. A typical expedient used in such devices is a generally V-shaped groove that is formed in a substrate material and which serves as a cradle to accept the fiber being positioned. Representative of such devices is that shown in United Stales Patent 4,756,591 (Fischer et al.), wherein a V-groove is formed in a silicon substrate and an elastomeric member is biased against the fiber to hold it in the groove. The groove may be stepped to provide a deeper groove segment to hold the jacket of the fiber within the device.

United States Patent 4,756,591 (Sheem) discloses a grooved silicon substrate having a pair of intersecting V- grooves therein. A fiber to be positioned is disposed in one of the grooves while a im is disposed in the other of the grooves. The shim may take the form of a tapered or an eccentric fiber, which wfien respectively slid or rotated under the first fiber serves to lift the same to bring the axis thereof into alignment with a reference axis. A cover may be positioned above the substfate to assist in clamping the first fiber into position.

United States Patent 4,802,727 (Stanley) also discloses a positioning arrangement for optical components and waveguides which utilizes a V-grooved structure. United States Patent 4,826,272 (Pimpinella et al.) and United States Patent 4,830,450 (Connell et al.) discloses arrangements for positioning an optical fiber that utilize members having frusloconical apertures therethrough.

It is believed that single crystalline silicon is the material of choice of the devices above mentioned because of the proclivity of crystalline silicon to be etched along precise crystallographic planes, thus forming precise grooves or structural features by photolithographic microfabrication techniques. Elchants^exist that act upon a selected crystallographic plane lo a differential degree than upon an adjacent plane,, permitting the needed precise control. V- grooves, in particular) can be etched to a controlled width and truncated depth. Under some conditions V-grooves may be etched in a self-liming operation. The photolithographic microfabrication process is generally described by Brodie and Muray, "The Physics of Microfabrication", Plenum Publishing, New York (1982).

Optical fibers include an inner core having a predetermined index of refraction surrounded by a cladding layer of a lower index. The inner core is the medium in which the optical energy is guided, while the cladding layer defines the index boundary with the core. The outer diameter of the fiber may vary in dimension about a predetermined nominal dimension. It has been seen, for example, that two nominally identical fibers from the same manufacturer may vary in outside diametrical dimension by as much as plus or minus four (4) micrometers. This fiber to fiber variation in outer diameter makes difficult the accurate positioning of the axis of the core of a fiber with respect to a predetermined reference axis.

In view of the foregoing it is believed advantageous to make use of the ability of microfabrication techniques to form accurate structures, channels and/or surfaces in a crystalline material to construct a positioning apparatus that will accurately position the center of the fiber, or of any other elongated generally cylindrical member having small dimensions (such as capillary tubing), with respect to a predetermined reference axis. Moreover, it is believed advantageous lo provide a positioning apparatus that consistently aligns the predetermined point on the fiber or other cylindrical member with the reference axis without requiring great technical skill, expensive apparatus, and extensive alignment procedures. SUMMARY OF THE INVENTION

The present invention relates to a positioning apparatus for positioning a predetermined point, such as the geometric center, on the end face of a cylindrical member, such as an optical fiber, along a predetermined reference axis. In the preferred case the positioning apparatus includes a first and a second arm, each of which has at least a First and a second sidewall that cooperate to. define a groove therein. The groove in each arm is preferably a converging groove so that when the arms are arranged in superimposed relationship the converging grooves cooperate to define a funnel-like channel over at least a predetermined portion of its length. The channel has an inlet end and an outlet end and a reference axis extending therethrough. A fiber introduced into the inlet end of the channel with its axis spaced from the reference axis, is displacable by contact with at least one of the sidewalls on one of the arms to place predetermined point on an end face of the member into alignment with the reference axis where it is there held by contact with die first and second arms. To guide the fiber toward the inlet end of the channel each of the first and the second arms includes a trough therein, each trough being disposed on an ar,m a predetermined distance behind the groove in that arm, so that in the dosed position the troughs cooperate to define a guideway.

The arms having the converging grooves therein may, as is preferred, be

from a first, closed, position to a second, centering, position. The superimposed arms are, in this instance, mounted cantilevered fashion, lo a foundation. Means is provided for biasing each of the arms with a substantially equal and oppositely -directed biasing force toward the first position. In the preferred implementation the biasing means comprises a reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the cylindrical member, generates a force on each arm to bias each arm toward the closed position.

It should be understood that so long as the arms are movable and biased toward the closed position, it is not required that the grooves formed therein are converging grooves. Accordingly, other positioning apparatus in which the arms are movable but in which the grooves in each of the arms have a form other than a converging groove are to be construed as lying within the contemplation of the invention. Succinctly stated, the present invention encompasses any positioning apparatus having arms that are movable whether the groove in each arm take the form of a converging groove or a groove of an alternate form. Alternately, the present invention also encompasses any positioning apparatus in which the groove in each arm is converging in form, whether the arms are movable or fixed with respect to each other.

In another aspect, the present invention relates to a fiber-to-fiber connector formed from confronting pairs of positioning apparatus. Such a connector is, in the preferred instance, disposed in a housing.

In whatever embodiment realized, it is preferred that the positioning apparatus be fabricated from a crystalline material, such as single crystal silicon, using microfabrication techniques. Each structural element of the positioning apparatus (viz., each of the arms and each foundation) is fabricated in mass on a wafer of silicon. The finished wafers are aligned, superimposed, and bonded_* and each of the resulting positioning apparatus severed from the finished assembly of bonded wafers. Alignment between superimposed wafers is assured using selected ones of a plurality of alignment grooves on each of the wafers and associated precise diameter fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detailed description thereof, taken in connection with the accompanying drawings, which form a part of this application, and in which:

Figure 1 is a perspective, exploded view of a positioning apparatus in accordance with the preferred embodiment of the present invention for positioning the center point on the end face of an optical fiber with respect to a predetermined reference axis;

Figure 2 is a perspective view of the positioning apparatus of Figure 1 in the fully assembled condition;

Figure 3 is a front elevation view of the assembled positioning apparatus of Figures 1 and 2, taken along view lines 3-3 in Figure 2;

Figure 4 is a sectional view, in elevation, of the assembled positioning apparatus of Figure 2, taken along section lines 4-4 in that Figure illustrating the truncated V-groove therein;

Figure 4A is a view generally similar to Figure 4 in which a full V-groove is formed in the positioning apparatus while Figure 4B is a view generally similar to Figure 4 in which both a full V-groovc and a truncated V-groove are formed;

Figure 5 is a plan view one of the arms of the positioning apparatus of Figure 1 illustrating the relationships of the axes of the groove and the guideway therein; Figures 6A and 6B, 7A and 7B, and 8A and 8B are diagrammatic elevational and end views of the action of the clips disposed on the arms of the positioning apparatus shown in Figures 1 and 2 in response to the introduction of a fiber thereinto; ^;'

Figures 9 and 10 are exploded and assembled perspective views, generally similar lo Figures 1 and 2, of another alternate embodiment of a positioning device in accordance with the present invention in which the arms have nonconverging grooves therein and iw. which the arms are articulably movable with respect lo each other along one axis only;

Figures 1 1 are 12 are sectional views taken along section lines 1 1 -1 1 and 12-12 in Figure 10;

Figures 13 and 14 are exploded and assembled perspective views, generally similar to Figures 1 and 2, of another alternate embodiment of a positioning device in accordance with the present invention in which only one of the arms has a nonconverging groove therein and in which both of the arms are articulably movable with respect to each other;

Figures 15 are 16 are sectional views taken along section lines 15-15 and 16-16 in Figure 14;

Figures 17 and 18 are exploded and assembled perspective views, generally similar to Figures 1 and 2, of an alternate embodiment of a positioning device in accordance with the present invention in which the arms have converging grooves therein*" and in which the arms are fixed with respect to each other;

Figure 19 is an end view taken along view lines 19-19 in Figure 18; Figure 20 is a side sectional view, taken along view lines 20-20 in Figure 18, illustrating the position of the fiber within the channel of the a positioning apparatus in accordance with the alternate embodiment of the invention shown therein;

Figure 21 is an exploded isometric view of a pair of positioning apparatus as shown in Figure 1 used lo form a fiber-to-fiber conneclor in accordance with the present invention while Figure 22 is an isometric view of the fully assembled connector of Figure 21 ;

Figures 23 and 24 are, respectively, a top view in section and a side elevation section view of a pair of positioning apparatus in accordance the embodiment of the invention as shown in Figure 17 used to form a fiber-to-fiber connector in accordance wiih the present invention;

Figures 25 and 26 are isometric views of a housing used for the fiber-to-fiber connector shown in Figures 21 and 22 in the open and in the partially closed positions, respectively, while Figure 27 is a section view of the housing of Figure 25 in the fully closed position taken along section lines 27-27 of Figure 26;

Figure 28 is a section view generally similar to Figure 27 of a housing used for the fiber-to-fiber connector shown in Figure 24;

Figure 29 is a isometric view of an alternate housing for a fiber-to-fiber connector formed of a pair of positioning apparatus;

Figures 30 and 31 are isometric exploded and assembled views, respectively, illustrating the use of a positioning apparatus in accordance with the present invention to position an optical fiber with respect lo the axis of an edge emitting active device, in which the device is surface mounted;

Figure 31 A is a side elevational view generally similar to

Figure 31 showing a positioning apparatus in accordance with the present invention positioning a lens with respect to an oplo-electronic component;

Figures 32 and, 33 are isometric exploded and assembled views, respectively, generally similar to Figures 30 and 31 , illustrating the use of a positioning apparatus in in accordance with the present invention to position an optical fiber with respect to the axis o a -device having active surface device, in which the device is edge mounted;

Figure 34 is a perspective view of a wafer used used to fabricate a plurality of arms or foundations used in a positioning apparatus in accordance with the present invention;

Figure 35 is ,a perspective view of a mask used in the photolithographic proςess forming a plurality of arms or foundations for a positioning apparatus in accordance with the present invention;

Figure 36 is an enlarged view of a portion of the mask used for creating a plurality of arms on the wafer 34;

Figures 37A through 37E are schematic representations of the process steps effected during fabrication of the wafer;

Figure 38 is is an enlarged view of a portion of the mask used for creating solder masks on the wafer; Figure 39 is an enlarged view of a portion of the mask used for creating foundations on the wafer;

Figures 40A through 40D are schematic representations of the steps used to form a plurality of fiber-lo-fiber connectors from superimposed wafers having the arms and foundations thereon;

Figure 41 is a definitional drawing illustrating the characteristics of a converging groove as that term is used in this application; and

Figures 42A through 42F are end views showing alternate arrangements of movable arms each holding a cylindrical member along at least three contact points in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following detailed description similar reference numerals refer to similar elements in all Figures of the drawings.

With reference to Figures 1 and 2 a positioning apparatus generally by reference character 20 in accordance with the present invention is shown in an exploded and in a fully assembled condition. As will be developed herein, in the preferred instance the positioning apparatus 20 is microfabricated from single crystal silicon or another differentially etchabie single crystal material. These materials are preferred because they permit the accurate formation of the structural features of the apparatus 20 using the process of differential etching. The positioning apparatus 20 is useful in accurately positioning a predetermined point on the end face of a cylindrical member, typically a point on the central axis of the member, along a reference axfs. Typically this reference axis is itself collinearly aligned with respect to another axis, as an operalive axis of a device operably associable with the cylindrical member. Throughout this application the description of ihe cylindrical member is cast in terms of an optical fiber, but it is lo be understood that the present invention may be effectively utilized with any other member having the form of small diameler cylindrical object. By way of example and not limitation, the positioning apparatus invention may be used to position a point on the end face of a length of microlubing or capillary tubing. By small diameter it is generally meant less than 0.04 inch (one (1) millimeter), but usually less than 0.020 inch. Moreover, it should be further understood that the term cylindrical is not to be strictly limited lo an object having a completely circular outer configuration, but would apply lo any object whose outer contour is symmetrical to its central axis. Thus, again by way of further example and not limitation, the positioning apparatus of the present invention may be used to position a point on the end face of a polygonal shaped member or an elliptical member.

As noted, the cylindrical member preferably takes the form of an optical fiber. The positioning apparatus of the present invention is particularly adapted to place a predetermined point P on the end face E of an optical fiber F along a predetermined "reference axis R. In practice the point P is the geometric center and lies on the axis A of the core C (Figures 6A and 6B) of the fiber F. The core C is itself surrounded by an outer cladding layer L. A jacket J is provided about the cladding layer L but is stripped from the fiber F prior to the insertion of the fiber into the posilioning apparatus 20. The jacket may comprise more than one layer. As discussed previously, the dimension of the outer diameter D of the cladding layer L of the fiber F may vary from fiber to fiber. Typically this diametrical variation from fiber to fiber is on the order of three (3) micrometers. This situation makes difficult the positioning of the point P along the reference axis R using the positioning devices of the prior art. The fiber may be a single-mode or a multi-mode fiber. As will be seen from the following the positioning capability of the positioning apparatus 20 is especially adapted for positioning the point P of a single mode fiber within the precise tolerances required to effectively couple light emanating from the single mode fiber into another fiber or to position the fiber with respect to an optical device.

With reference to Figures 1 and 2 it is seen that the positioning apparatus 20 includes a first and a second arm 22A, 22B, respectively. Preferably, each of the arms 22A, 22B is identically formed in a manner to be discussed, so the structural details of only one of the arms, e. g., the arm 22A, will be discussed. It should be apparent, however, that each structural detail of the arm 22A finds a counterpart in the other arm 22B. Accordingly, corresponding reference numerals with the appropriate alphabet suffix will denote corresponding structural details on the arm 22B. If the arms are not substantially identical (as, for example, in the embodiments of Figures 13 through 16 and Figure 42) adjustments must be made to provide the requisite biasing forces to maintain the point P on the reference axis R

The arm 22A includes a base portion 24A having a first major surface 26A and a second, opposed, major surface 28A. The base portion 24Λ extends along the full length of the arm 22A and the dimension of the central region 25A of the base portion 24A defines the basic dimension of ihe arm 22A. A clip generally indicated by the reference character 30A is defined at a first end of the arm 22A. The clip 30A is formed in a relatively thicker abutment portion 32A that lies on the first surface 26A of the arm 22A. The abutment 32A has a planar surface 34A thereon that preferably lies parallel to the first major surface 26A. To provide some feeling for the physical dimensions involved, the arm 22A has an overall length dimension on the order of twenty eight hundred (2800) micrometers and a width on the order of three hundred fifty (350) micrometers. In the central region 25A the arm 22A has a thickness dimension on the order of fifty (50) micrometers, while the remaining portion of the arm 22A has a thickness dimension on the order of one hundred twenty five (125) micrometers.

As may be better seen with reference to Figures 3 and 4 a generally converging V-shaped groove 36A is defined in the abutment 32A of the clip 30A by generally planar first and second sidewalls 38A, 40A, respectively, and the forward end region of the first surface 26A of the base 24A. The sidewall 38A has an upper edge 39A (Figure 1 ) thereon while the sidewall 40A has an upper edge 41 A thereon. It should be understood thai the term "planar" is meant to encompass a surface formed in a single crystal material by etching in which microscopic steps are of necessity produced owing to the lattice structure of the crystal.

With reference now to the definitional drawing of Figure 41 , the meaning of the term "converging" when applied to a groove (using the reference characters of Figures 1 and 2) may be made more clear. As used herein, a "converging" groove is a groove 36 defined from at least two planar sidewalls 38, 40 and has an enlarged inlet end 42A and a .narrower outlet end 43A. The respective upper edges 39, 41 of the sidewalls 38, 40 of llie groove 36 lie in a reference plane RP having a reference axis R lying therein. The planar surfaces 34 also lie in the reference plane RP. The reference axis R extends in the reference plane RP from the inlet end 42 lo the the outlet end 43 of the groove 36. Each point on the reference axis R is spaced in the reference plane RP an equal distance from the respective upper edges 39, 41 of the sidewalls 38, 40. The distance between the upper edges of the sidewalls decreases from the inlet end 42 to the outlet end 43 of the groove 36.

The surfaces of the sidewalls 38, 40 are equally and oppositely inclined with respect lo the reference plane at an angle A greater than zero and less than ninety degrees. The angle of inclination A is determined by the lattice structure of the crystal, and in the case of (100) silicon, is 54.74 degrees. The projections of the sidewalls 38, 40 inlersect in a line L that itself intersects the reference axis R forwardly past the outlet end 43 of the groove 36. The line L is inclined with respect to the reference plane RP at an angle B that is greater than zero degrees but less than ninety degrees. In the reference plane RP the upper edges 39, 41 of the sidewalls 38, 40 each converge toward the reference axis R at an angle C that is on the order of two and one-half lo five degrees (2.5 to 5) degrees, and most preferably at aboul three (3) degrees. The angle B is dependent upon the values of the angles A and C and typically the angle B lies in the range from about four (4) to five (5) degrees. As used herein a "fully funnel-like" channel is a channel thai is defined by the cooperative association of at least two converging grooves. A "partially funnel-like" channel is a channel that is defined by one converging groove and a surface.

From the foregoing it may be readily understood that a "uniform widih" groove is one in which each point on the reference axis R is spaced in the reference plane RP a uniform distance from the edges 39, 41 of the sidewalls 38, 40 as one progresses from the inlet end 42 to the outlet end 43 of the groove 36. The sidewalls of a uniform width groove may be inclined with respect to reference plane RP, or they may extend perpendicularly to it, as desired. A channel formed from one or two uniform widlfr grøove(s) is termed a "uniform width" channel. Such a channel may have a rectangular cross section in a plane perpendicular both lo the reference plane and to the reference axis, assuming no inclination of the sidewalls of the groove.

A tapering groove is one in which the planar sidewalls are perpendicular lo the reference plane but the distance in the reference plane between the reference axis and the edges of the sidewalls decreases as one progresses from the inlet to the outlet of the groove such that the extensions of the planar sidewalls intersect in a line that itself intersects perpendicularly with the reference axis.

In the preferred embodiment s-een in Figures 3 and 4 the groove 36 is a converging groove, and more preferably, is a V- groove truncate -.by -the presence of a third sidewall defined by a portion of the major surface 26 of the larjn 22 in which it is disposed. The truncated V-groove has the same depth throughout its ength when measured along a dimension line erected perpendicular lo the surface 34A of the abutment 32A in a direction extending toward the major surface 26A.

It should be!. understood that t'ltf- V-shape of the groove 36A may take alternate forms and remain within the contemplation of the. invention. For example, as seen in Figure 4A, the groove 36A may be defined by only the first and second sidewalls 38A, 40A, respectively, in which evenl the groove 36A appears a a full V-shape throughout its length. The apex 42A of ^' the groove 3 A thus appears throughout the full length of the groove 36A. Figure 4B shows another alternative arrangement in which a truncated V-groove (defined by the first and second sidewalls 38A, 40A, respectively, and the portion of the major surface 26A) extends for some predetermined axial distance while a full V-groove (defined by the first and second sidewalls 38A, 40A, respectively) extends for some second predetermined distance. Thus, as seen in Figure 4B, when measured along a dimension line erecled perpendicular to the surface 34A of the abutment 32A in a direction extending toward ihe major surface 26A ihe depth that the groove 36A extends into the abutment 32A is greater al its inlet end 42 (as indicated by the dimension arrow 44A) than it is at its outlet end 43 (as indicated by the dimension arrow 46A).

The fully truncated V-groove shown in Figure 4 is preferred. For purposes of ease of manufaclurability, as will be made clear herein, it is also preferred that the groove 36A does not converge throughout the full axial distance through the abutment 32A. Owing to the provision of tabs 48A, 48B (Figures 1 and 5) formed near the ends of the abutments 32A, 32B, the sidewalls 38A, 40A defining the groove 36A do not converge throughout the full length of the groove, but define a short uniform width portion just past the converging portion of the groove 36A. The overall axial length of the groove 36 (including bolh ihe converging and the uniform width portions) is on the order of three tenths (0.3) of a millimeter, while the uniform width portion of the groove occupies an axial length of one tenth (0.1 ) of a millimeter. As is believed best seen in Figure 5 the converging and nonconverging portions of the groove 36A have a common axis 50A associated therewith.

Again with reference to Figure 2, an extended enlargement region 54A having a planar surface 56A lies on the base portion 24A of the arm 22A spaced a predetermined axial distance 58A behind the abutment 32A. The distance 58A is on ihe order of one (1 ) millimeter. The surface 56A is coplanar with the surface 34A. The enlargement 54A is provided with a nonconverging, uniform width, truncated V- shaped trough 60A defined by inclined planar sidewalls 62A, 64A, respectively, arid, by a portion of the major surface 26A of the base portion 24A near the second end thereof. In the embodiment shown in Figures 1 and 2 the trough 60A is uniform in depth along its axial length, as measured with respect to a dimension line erected perpendicular to the surface 56A toward the major surface 26A. The trough 60A communicates with a converging lead-in 68A. If desired, the walls 62A, 64A may be inclined with respect to each other so that the trough 60A may be a full V-shape or a partial V- shape, similar to the situation illustrated in connection with Figures 4A and 4B for the, groove 36A. Alternatively, the walls 62A, 64A defining tfe troughs 60A, 60B may be parallel or otherwise conveniently orieynled with respect to each other. As is believed best seen in Figure 5 the trough 60A and the lead- in 68A have a comrrtpn axis 70A. The length of the trough 60A and associated lead-in 68A is on the order of 1.59 millimeter.

Figure 5 is a plan view of one of the arms 22A. In the preferred implementation the axes 50A, 70A (respectively through the groove 3.6A and the trough/lead-in 60A/68A) are offset a predetermined distance 72 in the reference plane RP (the plane of Figure 5). Preferably, ihe offset 72 is at least one-half ihe difference between the diameters of the anticipated largest and smallest fibers to be positioned. As will become clearer herein offsetting the axes 50A, 70A of the structures 36A, 60A 68A facilitates the centering action of the positioning apparatus 20 by insuring that a fiber, as it is introduced into the apparatus 20, is biased lo strike one of the sidewalls 38A, 40A forming the groove 36A (and analogously, ihe sidewalls 38B, 40B forming the groove 36B). This insures wall contact with the fiber at at least two spaced locations. However, the presence of the offset 72 necessitates additional manufacturing considerations, as will be discussed. It should be noted that the force resulting from biasing the fiber in the manner just discussed (or the force on the fiber due to gravity) is much smaller in magnitude than the biasing force of the arms which serves lo center the fiber on the reference axis.

In the assembled condition the arms 22A, 22B are disposed in superimposed relationship one above the other, with the groove 36A, the iroug 60A and the lead-in 68A on the one arm 22A registering with ihe corresponding groove 36B, irough 60B and lead-in 68B on the other arm 22B. The registered converging grooves 36A, 36B in the abutments 32A, 32B cooperate to define a generally fully funnel-shaped channel 92 having an input end 94 (Figure 4) and an output end 96 (Figures 4 and 5). (Note that if the tabs 48 .are provided, the channel 92 so defined has a uniform width portion just preceding the outlet end 96 thereof.) The reference axis R extends centrally and axially through the channel 92. Preferably, ihe reference axis R lies on the intersection of the reference plane RP (which contains the conjoined surfaces 34A, 34B) with the plane containing the axes 50A, 50B of Ihe converging grooves 36A, 36B.

The registered troughs 60 and lead-ins 68 cooperate to define a guideway 98 (Figure 2). Similarly, the axis R' through the guideway 98 lies on the intersection of the plane containing the conjoined surfaces 56A, 56B of the enlargements 54A, 54B (which is the reference plane in the preferred case) with the plane containing the axes 70A, 70B (Figure 5) of the trough/lead-in 60A/68A, 60B/68B. The axes R and R¹ both lie in the reference plane RP (the plane of Ihe surfaces 34A, 34B, 56A, 56B) although the axes R and R' are laterally offset with respect to each other in this reference plane by a predetermined offset distance 100. For a fiber the offset distance 100 is typicafly on the order of five (5) micrometers.

The inlet end 94 of the fully funnel-like channel 92 (best seen in Figures 4 aπcfv 5) is sized to circumscribe and thereby to accommodate a fiber F whose cladding layer L (or outside surface) has the largest expected outer diameter dimension. The outlet end 96 of ihe channel 92 (best seen in Figure 3) is sized to circumscribe and thereby to accommodate a fiber F whose cladding layer L (or outside surface) has a dimension somewhat smaller than the minimum expected outer diameter dimension of the fiber F. In practice, to position an optical fiber having a nominal outer diameter dimension of one hundred twenty five - 125 ) . micrometers, the largest expected outer diameter dimension is on the order of one hundred twenty nine ( 129) micrometers while the smallest expected outer diameter dimension is on the order of one hundred twenty one ( 121 ) micrometers.

The dimension of each of ihe troughs 60A, 60B is such that the guideway 98 so formed by the registered troughs 60A, 60B is sized lo accommodate a fiber F whose cladding layer L has the largest expected outer diameter dimension. Despite its dimension with respect lo ihe fiber, the guideway 98 assists in the insertion of a fiber into Ihe positioning apparatus 20 and is advantageous in this -regard.

In the embodiment shown in Figures 1 through 5 the surfaces 34A, 34B on the respective arms 22A, 22B, respectively, are, when in a first, closed, position, either in coniacl with each other or, if desired, within a predetermined close distance lo each other. For optical libers the predetermined close di.slaπce is typically on ihe order of five (5) to twenty-live (25) micrometers. In this embodiment the planar surfaces 34A, 34B on the abutments 32A, 32B of the clips 30A, 30B are not secured lo each other and may move to a second, centering, position, as will be described. The planar surfaces 56A, 56B on the respective arms 22A, 22B are secured to each other by any convenient means of attachment, as by fusing or soldering. It should be understood thai any other mechanical securing expedient may be used to attach or otherwise hold together the surfaces 56A, 56B to each other.

The positioning apparatus 20 further includes, in the preferred instance, a mounting foundation 74 (Figures 1 and 2). The mounting foundation 74 is provided with a planar attachment surface 76 thereon. A step 78 in the mounting foundation 74 serves to space Ihe attachment surface 76 a predetermined clearance distance 80 from a second surface 82. The opposite major surface, e.g., the surface 28A, of the arm 22A is secured, as by fusing or soldering, to the planar attachment surface 76 on the foundation 74. Of course, it should be again understood that any alternative mechanical attachment expedienl may be used to attach or otherwise hold together the second major surface of the arm to the foundation 74.

Although the second surface 82 of the foundation is shown in the Figures as being generally planar in the preferred case, il should be understood that this surface 82 may take any desired configuration. As will be more fully appreciated herein, so long as the opposite surface 28A of the arm 22A affixed to the foundation 74 is, at least in the region of the clips 30A, spaced at least a predetermined clearance distance 80 from the second surface 82 (assuming ihe surface 82 is parallel to the surface 76), the movement of the clip on the arm 22A attached to the foundation (in Ihe drawings, the clip 30A) to be described will not be impeded. 22

When assembled, the clips 30A, 30B disposed at the ends of the arms 22Λ, 22B,, respectively, are supported in a cantilevered fashion from the conjoined enlargements 54A, 54B at the opposite ends of the arms. The arms 22A, 22B are rigid in x-z plane, as defined by the coordinate axes shown in Figure 1. Moreover, the relatively thin dimension of the central region 25A, 2513 of the base portion 24Λ, 24B of the arms 22A, 22B axially intermediate the respective abutments 32Λ, 32B and the enlargements 54A, 54B acts as a flexure and permits each arm 22 to flex_* springboard fashion, in the directions of the arrows 88 in the y-z plane. As used herein it should thus be appreciated that a flexure is a spring member that is rigid in one plane and is constrained lo flex in the orthogonal plane. It should furth r be appreciated that when a clip 30A, 30B is defiected in its corresponding respective direction 88A, 88B, the resiliency of the ihinner central region 25 A, 25B of the base 24A, 24B, acting as a flexure, defines means for biasing the clips 30A, 30B toward the first, closed, position. The biasing force acts on the clip 30A, 30B in a direction shown by the arrows 90A, 90B, counter to the direction of motion 88A. 88B of the arms. The biafing forces must be substantially equal and in opposite directions. In general, whatever the number of arms used in the positioning apparatus, the force on each arm passes through the reference axis and the sum of forces when in the centering position position substantially equals zero. Biasing means employing the thinner central region of the base 24 as a flexure (as shown in ihe Figures I to 4) is preferred, because when implemented in a single crystal material using a microfabrication technique precise control of the biasing forces is able to be attained. Typically ihe bias force on eacli arm is on ihe order of five (5) grams.

It should be understood that any other convenient mechanism may be used to define the means for biasing the arms and the clips 30 thereon toward the closed position so long as the force on each arm passes through ihe reference axis and the sum of forces on the arms when they are in the centering position is substantially equal lo zero. Whatever form of biasing means is selected the bias force must increase with deflection of the arm.

-o- -o-

Having defined the structure of the positioning apparatus

20, the operation thereof in positioning a point P on the end face E of an optical fiber F along a predetermined reference axis R may be readily understood in connection with Figures 5 through 7.

In operation the fiber F is inserted into the positioning apparatus 20 in the direction of ihe arrow 102 (Figure 6A). The lead-in portions 68A, 68B (Figure 1) cooperate to guide the fiber F into the guideway 98 (Figure 2) defined by the registered troughs 60A, 60B in ihe enlargements 54A, 54B

(Figure 1). Because the axis R' of the passage 98 is offset from the axis R of the fully funnel shaped channel 92 Ihe guideway 98 serves to guide the face E of the fiber F toward the inlet end 94 of the channel 92 at a predetermined azimuth with respect to the axis R.

As a result the end face E of the fiber F enters the channel 92 and is initially displaced through contact with at least one of the sidewalls 38Λ υr 38 , 40A or 40B (or portions of the major surface 26A, 26B, if these are used to define the grooves 36Λ, 36B, as in Figure 4 ) on one of ihe clips 30A, 30B, respectively, to Ihe exieni necessary lo place a predetermined poini P on an end face E of the fiber F into alignment with ihe reference axis R. At some point on the palh of axial insertion of the fiber F into the channel 92, as the end E of the fiber F moves toward the outlet end 96, the outer diameter of the cladding layer L of the fiber F exceeds the dimension of the channel 92. The arms 22A, 22B respond to a force in the directions 88A, 88B imposed thereon by the fiber F by moving against the biasing force from the first, closed, position, shown in Figures 7A, 7B, toward a second, centering, position showing in Figures 8A, 8B. In the centering position the clips 30A, 30B open against the bias force acting in the directions 90A, 90B generated by the flexing of the arms 22A, 22B, to separate Ihe surfaces 34A, 34B thereon. However, this movement of the . arms 22A, 22B from the first toward the second position maintains the point P on the end face E of the fiber F on the reference axis R. The end face E of the fiber F thus exits through the outlet end 96 of the fully funnel shaped channel 92 with the point P precisely aligned with (i.e., within one micrometer of) the reference axis R, as is shown in Figures 8 A, 8B. The fiber F is held in this position by contact wilh the sidewalls 38A, 38B, 40A, and 40B.

If the tabs 48A, 48B are formed on the abutments 32A, 32B these labs cooperate to define a passage of uniform width along its axial length that communicates with the outlet of the funnel-like channef. The fiber F passes through and emerges from such a conduit with the point P on the end face of the fiber still along ttte reference axis R.

It should be noted thai ihe movement of the arms could be other than the flexing thereof as described heretofore. It therefore lies within the contemplation of this invention to have the arms move in ni f other manner, as, for example, by any form of pinned or jointed (articulated) motion.

-o-O-o- With reference now lo Figures 9 through 12 an alternate embodiment of the positioning apparatus 20' in accordance with the present invention is shown. In this embodiment the arms 22' are, similar lo the embodiment earlier discussed, articulably movable in cantilevered fashion with respect to each other against the bias of the flexure defined by the central portion 25' thereof. However, the grooves 36' formed in the arms 22' are not converging grooves, but are uniform width grooves. Accordingly the channel 92' formed by the cooperative association of the arms 22' when superimposed one on the other is a uniform widlh channel. The maximum dimension of such a channel 92' in the plane perpendicular to the reference R is less than the outside diameter of the smallest anticipated fiber F.

A further modification to the positioning apparatus 20' may be seen from Figure 12. It is first noted thai the planar walls 62', 64' of the troughs 60' are parallel, rather than inclined with respect to each olher. Moreover, the offset 100' between the axes R and R' lies in the vertical plane, that is, in the plane containing the axes 70' of the troughs 60', as opposed to being offset laterally (i.e., in the plane containing the surfaces 56'). The lead-in portions 68'A, 68'B are ommitted here but may be provided.

In operation, a fiber F is inserted into the positioning apparatus 20' and guided by the passage 98' defined by the registered troughs 60'A, 60'B. Because the axis R' of the passage 98' is vertically offset from the axis R of the channel 92' ihe surface 26'B of the arm 22'B bounding the passage 98' serves to guide the fiber F toward the inlet end 94' of the channel 92'. The fiber F enters the channel 92' and contacts with the edges of the sidewalls 38'A, 38'B, 40'A and 40'B. Due to the sizing of the grooves 36'A, 36'B the fiber F does not touch the major surface 26'A, 26'B of the arms 22'A, 22'B, 26

respectively. The fiber may be chamfered or tapered or a mechanical device may be used to facilitate insertion of the fiber into the channel 92'.

Since the fiber F exceeds the dimension of the channel 92' the clips 30'A, 30'B are displaced from the first, closed, position toward a second, centering, position. This movement of the clips 30'Λ, 30'B maintains the point P on ihe end face E of the fiber F on the reference axis R. The end face E of the fiber F thus exits through the outlet end 96' of the channel 92' with the point P precisely aligned on the reference axis R. The fiber F is held in this position by contact with the edges of the sidewalls 38'A, 38'B, 40'A, and 40'B, as indicated by the character LC. _t

The embodiment of Figures 9 to 12 can be further modified, as seen in Figures 13 to 16. In this modification, the arm 22"B differs øm those shown earlier in that no groove is provided therein. In ibis embodiment, if the groove is a converging groove, a partially funnel-like channel is defined. The fiber F is guided by contact against the major surface 26"B and held in position on the reference axis R by contact with the major surface 26"B and the edges of the sidewalls 38'A, 38'B, again as indicated by the character LC.

o- -o-

Figures 17 and 18 are exploded and assembled perspective views, generally similar to Figures I and 2, of another alternate embodimenl of a positioning apparatus 20"' in accordance with t je present invention while Figure 19 shows Ihe end view thereof. In this embodimenl. instead of the arms being articulably movable as described earlier, ihe arms are fixed relative lo each olher. Each of the arms 22"'Λ and 22"'π has a converging groove therein and lire channel 92"' formed by the cooperative association of the arms 22'" when superimposed one on the olher is fully funnel-like in form. The channel 92"' defines a minimum dimension in the plane perpendicular to the reference R that is, near its outlet end, less than the outside diameter of the smallest anticipated fiber F.

In operation, a fiber F is inserted into the positioning apparatus 20'" and guided through the passage 98"' toward the inlet end 94'" of the channel 92'". The fiber F enters the funnel-like channel 92"' and is guided by contact with one or more of the sidewalls 38'A, 38'B, 40'A and 40'B and/or major surfaces 26"'A, 26"'B to place the point P of the fiber F on the axis R. However, since the arms 22"' are fixed wilh respect to each other, the fiber F can only advance within the channel 92"' to the axial location where the outer diameter of the fiber F equals the local dimension of the channel 92"'. At this axial location within the channel the fiber is held in position by a minimum of four point contacts (indicated by the characters PC) between the fiber F and each of the sidewalls 38'A, 38'B, 40'A, and 40'B. The dimension of the channel is such that the fiber is not able lo contact the major surfaces of the arms 22"' when it is held along the reference axis R. Figure 20 illustrates the fiber as the same is held within the channel 92"'. The axial spacing 104 between the end face E of the fiber F and the outlet end 96'" of the channel 92"' varies, dependent upon the outer diameter dimension of the fiber F.

-o- -o-

The positioning apparatus in accordance with any of the above-described embodiments of the invention may be used in a variety of applications which require the precise positioning of a point P on the end face E of a fiber F along a reference axis R. In Figures 21 and 22, a pair of positioning apparatus 20-

20-2 (corresponding to the embodiment shown in Figures 1 and 2) are arranged lo define a fiber-lo-fiber connector generally indicated by the reference character 120. In this arrangement the apparatus 20- 1 , 20-2 are confrontationally disposed wilh iespect lo ihe olher so thai ihe outlet ends 96 of the respective channels 92 therein are spaced a predetermined distance 122 with the respective reference axes R therelhrough being collinear. To effect such an arrangement the foundation 74 is extended in an axial direction and each axial end thereof is provided with a planar attachment surface 76. Each positioning apparatus 20-1 , 20-2 is mounted to its respective attachment surface 76.

The fibers f and F-2 to be connected are inserted into the lead-ins 68 of the respective positioning apparatus 20-1 , 20-2. Each positioning apparatus 20-1 , 20-2, acting in the manner described above, serves to place the point P on the end face E , of the respective fiber F-1 or F-2 along the collinearly disposed axes R'. The fibers F-1 , F-2 are inserted in to the respective apparatus_^ 20-1, 20-2 until the end faces E, E' abut. The ends E of the fibers F-1 , F-2 are secured due to the above- described holding a_uction of e positioning apparatus. If desired an suitable index matching adhesive, such as an ultraviolet curing adhesive such that manufactured and sold by Electro-Lite Corporation, Danbυry, Connecticut as number 82001 ELC4480, may be used.

The fiber-to-fiber connector may be implemented using any of the above-discussed alternative embodiments of the positioning apparatus. In the event a pair positioning apparatus as shown in Figure 17 is used (see Figures 23 and 24), the confronting ends of the positioning apparatus 20"'-l , 20"'-2 are preferably abutted and secured, or the pair of positioning apparatus formed integrally with each olher. The spacing 122 between the end faces E of the fibers F-1 , F-2 is, in this embodiment, defined by the sum of the distances 104-1 , 104-2. The spacing 122 is filled with an index matching material, such as the adhesive defined above. To this end, an access port 124 is provided lo permit the introduction of the index matching material into the region between the confronting end face of the fibers F-1 , F-2.

Prior to insertion into the positioning apparatus (of whatever form) it should be understood thai the jacket J (Figure 29) of the fiber F is stripped in its entirety a predetermined distance from the free end thereof. The exposed portion of the fiber is cleaned with alcohol. The fiber is cleaved to form the end face E. If desired the end face E may be ground into a convex shape lo yield a point or be lensed.

-o-O-o

If desired the fiber-lo-fiber conneclor 120 may be disposed in a suitable housing 130 (figure 25). The preferred form of the housing 130 is generally similar to that disclosed in United Stales Patent 4,784,456 (Smith), assigned to the assignee of the present invention. This patent is hereby incorporated by reference herein. The housing 130 includes a base 132 and a cover 134. The base 132 is, in all cases, provided with a recess 136 that is sized to closely receive the connector 120. If the conneclor 120 is realized using any form of the positioning apparatus that articulates, the cover 134 must be provided with a corresponding recess 138 located so as to permit the articulaling motion of the arms of positioning apparatus used lo form the conneclor. If the connector 120 is realized using the form of the positioning apparatus shown in Figures 23 and 24, the recess 138 need not be provided. Such a housing 130 is shown in Figure 28. The cover 134 sis segmented into three sections, 140A, 140B, 140C, each which is hinged to the base 132. The base 132 has, adjacent lo each end of the recess 136, V-shaped grooved regions 142 , 142B. The top end sections 140A, 140B each contain respective generally lapered lands 143A, 143B. Each of the lands has serralions 145 A, 145B respectively thereon.

In use a connector is inserted in the recess 136 of the housing 130. It is there held in place by friction but may be otherwise secured if desired. The central section 140C of the cover may then be closed, if desired. An optical fiber having a predetermined length of its jacket J stripped and cleaned, is inserted through one of the V-shaped grooved regions 142A, 142B to dispose the stripped end of the fiber into the connector 120. The grooved region serves to properly orient and position the fiber with respect to the connector 120 in the recess 136. The associated top end section 140A, 140B, as the case may be, is then closed and latched lo the corresponding portion of the base 132 (Figure 25, wilh the fiber ommitted for clarity). When the lop is secured to the base the serrations 145 act against the jacket of the fiber to urge, or to bias, the fiber toward the connector. A second fiber is correspondingly introduced into the housing and connector in an analagous manner. If not already done so, the central section 140C of the cover is ihen closed. The housing 130 is preferably formed by injection molding.

As seen in Figure 29, in another form the housing 130 may be implemented using a mass 160 of index matching material, such as that identified above. The mass 160 extends over both the connector 120 (lo embed the same therein) and some predetermined portion of the jackets J of the fibers F-1 , F-2. -O-0-O-

The reference axis R on which the point P of the fiber F is positioned may itself extend collinearly with the axis X of any of a variety of devices. Accordingly, a positioning apparatus 20 may be used to accurately position the point P on the end face E of ihe fiber F with respect to the axis X of a particular device 170. Figures 30, 31 and Figures 32, 33 illustrate several examples of the use of a positioning apparatus 20 to locate a fiber F along an axis X of a device 170. The device 170 may, for example, be realized by any active optical component, such as a solid state laser, a photodiode, a light emitting diode, whether these devices are edge active devices or surface active devices. Although in ihe discussion that follows the reference character 20 is used to indicate the positioning apparatus, it should be understood that any one of the embodiments of the positioning apparatus heretofore described may used.

When used in connection with an edge active device 170 the arrangement in Figures 30 and 31 is preferred. In this arrangement the foundation 74 is axially extended to define a pedestal 174 at the axial end thereof. The upper surface 176 of the pedestal 174 defines a planar attachment surface. The surface 176 is spaced a predetermined distance above the attachment surface 76 or otherwise located such that when the active optical component 170 is mounted the surface 176 the axis X of the device 170 and the reference axis R are collinear. With the axes R and X collinear, the positioning of the point P on the fiber F along the axis R will automatically position that point P in the same relationship with the axis X. The device 170 must be accurately mounted on the surface 176 so that its axis X is collinearly aligned with the axis R. To mount the device 170 ihe surface 176 may be provided with a layer of solder layer, such as a gold/tin solder. The device 170 may have a corresponding layer of the same material. Ti device 170 is positioned on the surface 176 using a suitable micropositroning apparatus, such as a vacuum probe. The device is aligned to the edge, heated above ihe melting point of the solder and cooled, so that the solder forms a bond.

When used with a surface active device, as seen in

Figures 32 and 33, the active surface of the device 170 is secured to the frσnl surface 178 of the pedestal 174. Attaching the device to the front surface 178 is believed to provide sufficient bonding area to secure the device 170 to the positioning apparatus 20. The surface 176 of the pedestal 174 is relieved to avoid obstruction between the active region of the device 170 and the end face E of the fiber F.

It should also be appreciated, as is illustrated in Figure 31 A, that the positioning apparatus in accordance with any one of the embodiments heretofore described may be configured to accurately position a lens, such as a ball or a rod lens L, with respect to the axis }f of the device 170 .(whether die same is an edge active or a surface active device). The positioning apparatus would be modified to provide a seat 3 I S in the clips 30 thereof sized to accept the lens L.

-o-O-o- The photolithographic microfabrication technique used to manufacture a positioning apparatus 20 may be understood from the following discussion taken in conneclion with Figures 34 to 40. Although the discussion is cast in terms of the manufacture of a fiber-lo-fiber conneclor 120 using the preferred embodiment of the positioning device 20, as shown in Figure 22, the teachings are readily extendable to the manufacture of any of the embodiments of the positioning apparatus heretofore described, including their use in the various olher applications previously set forth.

A silicon wafer 200 having an appropriate predetermined crystallographic orientation is the starting point for fabrication of the arms 22 of a positioning apparatus 20 in accordance with the present invention. It should be understood that other single crystalline substrate materials, such as germanium, may be used provided appropriate alternative etchanls and materials compatible with Ihe selected alternative substrate are used. The wafer 200 is polished on at least one surface. Suitable silicon wafers are available from SEH America, Inc., a subsidiary of Shin-Etsu Handotai Co. Ltd., Tokyo, Japan, located at Sparta, New Jersey. It should be understood that the wafer 200 can be of the "p-type", "n-type" or intrinsic silicon.

The substrate material is preferably ( 100) surface silicon because this material can be etched by anisolropic etchants which readily act upon the (100) crystallographic plane but substantially do not etch the (1 1 1 ) plane. As a result the preferred truncated V-shaped grooves 36A, 36B, the troughs 60A, 60B, the lead-ins 68A, 68B and Ihe central region 25A, 25B of the arms 22A, 22B between the abutments 32A, 32B and the enlargements 54 A, 5 B are easily formed. The width and depth of such features are dependent upon the preselected width of the opening in the photolithographic mask being used and the lime during which the etchanls are permitted to act. Etchanls operate on 100 surface silicon in an essentially self- limiling manner which property is useful in forming a full V-groove. One of skill in the art will recognize that if other cross-section configurations are required, olher predetermined crystallographic orientations of the silicon may be used. For example, if square cross-section fealures are desired, (1 10) surfaces silicon wafers can be used. Other cross sectional configurations for the features are, however, significantly more expensive and, as will be seen later, would require a more complicated configuration to obtain the fiber centering action equivalent to thai inherent in a V-groove.

Figure 34 is a plan view of the wafer 200. The wafer 200 has peripheral flats 201 and 202, as specified by the SEMI Standard. The flats 201 , 202 primarily indicate orientation of the crystallographic structure of the silicon and are also used for wafer identification and mask alignment. The longer flat 201 indicates the direction of crystallographic plane (1 10). The shorter flat 202 is placed a predetermined angular amount on the periphery of the wafer with respect to the flat 201 , the magnitude of the angle depending upon the doping of the crystal. t_* As will be developed, the peripheral regions 203 of the wafer 200, when prepared, carry alignment grooves, while the central region 204 of the wafer 200 has the structural features of the arm or foundation, as the case may be, of the positioning apparatus formed ihereon.

Figure 35 sliows a mask 210 with a patterns 212 of orthogonal alignment grooves thereon. The grooves in each pattern 212 are graduated in size to accommodate various sized (diameter) quartz alignment fibers. The grooves 212 have a V-shaped cross section to accept fibers ranging in width from about 0.004825 inches (0.123 mm) lo 0.005000 inches (0.127 mm) in 0.039370 inch (0.1 mm) steps, five grooves 212 having been illustrated. The groove width (at ihe open top of the groove) is larger than the diameter of the fiber so that the center of the fiber is substantially coplanar with the surface of the wafer when the fiber is disposed in its associated groove. Accordingly, for a 0.123 mm fiber, a groove 0.1506 mm is provided. Similarly, for a 0.124 mm fiber, the open top dimension of the groove is 0.1518 mm. For a 0.125 mm fiber, the open lop dimension of the groove is 0.1531 mm; for a 0.126 mm fiber the open top dimension of the groove is 0.1543 mm.; and for a 0.127 mm fiber, ihe open lop dimension of the groove is 0.1555 mm.

A central area 214 of the mask 210 has provided thereon a repetitive pattern 220 (one of which is shown in Figure 36) containing to a predetermined number of structural features (i.e., arms or foundations) of the positioning apparatus 20 being formed. Since the typical wafer 200 is about 3.9381 inches (101.028 mm) in diameter and a typical connector 120 measures about three hundred fifly (350) micrometers at the widest location and is about two thousand eight hundred (2800) micrometers in length, the structural features for approximately one thousand (1000) connectors 120 may be formed from the central region 204 of the wafer 200.

Figure 36 is an enlarged view of a portion 220 of the pattern provided on the central region 214 of the mask 210. In Figure 36, the pattern illustrated is thai used to form a plurality of conjoined arms 22 used in a connector 120 (Figure 22). The pattern 220 is formed on the surface of the central region 214 of the mask 210 using a well-known step and repeat process to cover the entire area.

The repetitive patlern 220 shown in Figure 36 is comprised of a plurality of columns 224 which are defined between an array of adjacent parallel scribe lines 226 and a first and a second- separation line 227A and 227B. Each column 224 contains ten (10) discrete zones 228 A through 228E that are symmetrical within the column 224 aboul a cutting line 230.

Seen between two next adjacent scribe lines 226 is the configuration of two arms 22 joined front end to front end. Seen between three next adjacent scribe lines 226 is the configuration of two arms 22 joined lengthwise side to side. The zone 228A corresponds to features defining the region of the lead-in 68 A of an arm 22A. The zone 228B corresponds to features defining Ihe region of the trough 60A of the arm 22A. Similarly, zone 228C corresponds to the central portion 25A of the arm 22A, while he zone 228D corresponds to features defining the region of the converging groove 36A on the arm 22A. The axis 50A of the converging groove 36A is offset from the axis 70A of the trough 60A by the offset distance 100. Finally, if provided, the Zone 228E corresponds to features defining the region of the tabs 48 A of an arm 22A. Note that in the mask illustrated in Figure 36 the position of ihe offset 100 on one side of the cutting line 230 is reversed from the position of the offset 100 on^* the opposite side of the cutting line, although this arrangement is not necessarily required.

The repetitive patlern for a mask of the arm 22B will be similar to that shown in Figure 36 except thai the direction of the offset distances 100 for ihe arm 22B will be the mirror image of the pattern for the arm 22A. As will be come clearer herein, this mirror image relationship between the offsets is necessary so lhat^r so that features on the resulting arms 22A, 22B will register with each olher when one is inverted and superimposed on the other. Of course if the offset 100 is eliminated, masks- for the arms 22A and 22B will be identical. The cross-hatched areas shown in Figure 36 preferably correspond to those areas of the central region of the wafer 200 that will be protected by a layer of resist material (as will be described) while the areas shown without hatching will be left unprotected during subsequent etching steps. A negative resist is employed but it should be apparent thai the location of the hatched and clear areas of Figure 36 may be reversed if desired. This would alter somewhat subsequent steps, but in a manner known to those in the art.

Figures 37A through 37E illustrate the process steps whereby a wafer 200 of crystalline silicon may be formed into an array of arms 22A corresponding to the array shown on the mask of Figures 35 and 36. As seen in Figure 37A the wafer 200 is preliminarily covered with a layer 232 of a material that acts in a manner similar to a mask. Silicon nitride (SJ3N ) is preferred, and is surfaced onto the polished operative surface 200S of the silicon wafer 200 by thermally growing the silicon nitride layer in an oxygen atmosphere at elevated temperature (circa seven hundred fifty (750) degrees Celsius), as is known. As indicated, silicon nitride is used because available etchants that attack silicon will also attack known photoresists but will not affect silicon nitride. A suitable nitride layer is grown onto the wafer by CVD Systems and Services, Incorporated, Quakertown, Pennsylvania.

The layer of silicon nitride 232 is then covered with a photoresist 234. Preferred is a positive resist, such as the mixture of 2-ethoxyelhyl acetate, N-butyl acetate and xylene sold by Shipley Company, Incorporated of Newton,

Massachusetts, as "Microposit Photoresist" 1400-37. The resist is spun onto the surface of ihe silica nitride in accordance with instructions set forth in the Shipley Microelectronic Products Brochure (1984) using standard apparatus such as that available from Headway Research Incorporated of Garland, Texas under model number ECR485.

The mask 210 is mounted atop the wafer 200 and is aligned with respect lo ihe flats 201 , 202 of the wafer 200 using alignment bars 235. Thus, in a finished wafer the alignment grooves 212 are precisely positioned with respect to the flats on the wafer through llϊe use of alignment bars 213 on the mask. The wafer 200 is exposed lo ultraviolet light through the mask 210 and subsequently developed.

*_*

Since a positive resist is used the unexposed areas of the resist are washed away using de-ionized water, leaving the layered arrangement of exposed, hardened resist 234, silica nitride 232 and wafer 200, as shown in Figure 37B.

Next the patlern of the mask 210 is etched into the silica layer 232. Phosphoric acid (H3PO₄) is preferred. This step results in the arrangement shown in Figure 37C. Those skilled in the art will recognize thai process variables such as, for example, concentration, time and temperature are all adjusted appropriately to qptimize results in all of the wet processing steps described.

Thereafter, a second, differential, etching step is performed lo etch the silicon lo form ihe features of the arms 22A. Preferably using an anisolropic etchant such as ethylene diamine ("ED") pyrφcatechol ("P") and water. A mix of 750 ml ED, 120 gm P and 240 , ml water is preferred. A two-step etch using potassium hydroxide (KOH) may also be used if desired. This etching produces the struclural feature in the surface of ihe silicon illustrated schematically in Figure 37D by reference character 236. The depth of the feature 236 is controlled by controlling the etching lime, as is well known. Of course, differential etching is self-limiting for the inside angles of the structure, if left to proceed.

The silicon nitride layer 232 is then removed by etching with phosphoric acid and a layer of silica, i.e., silicon dioxide, is grown on the surface. Next, resist is deposited on the surface of the wafer and is imaged through a mask, as shown Figure 38. This results in a layer 238 of hardened resist being formed on those predetermined portions of the wafer that are to be bonded (corresponding to zones 228C through 228E and to troughs 60 (see Figure 36)).

The silicon layer is then etched from areas that are not to be bonded (See, Fgiure 37E) using hydrofluoric acid (HF). The resist layer 238 is stripped using acetone, leaving a finished wafer ready for bonding.

This completes the fabrication of the first wafer 200 having the array of arms 22A thereon.

^■o-O-o -

As noted earlier, since the axis of the guideway 98A is offset from the axis of the groove 92A, the mask for the arms 22B is nol identical with the mask used to form ihe arms 22A. Accordingly, a second wafer having an array of arms 22B thereon must be prepared in accordance with the method steps illustrated in Figure 37. The finished second wafer (not specifically illustrated but hereinafter referred lo by character 200') is similar in all respects except in location of the offset 100.

A third wafer 200" is prepared using a foundation mask, a portion of which is shown in Figure 39. Figure 39 is an enlarged view of a portion of the pallern 220' provided on the central region of the foundation mask (analagous to the pattern of the arm mask shown in Figure 36). The repetitive pattern 220' is comprised of a plurality of columns 244 which are defined between an array of adjacent parallel scribe lines 246 and a first and a second . separation line 248A and 248B. Each column 244 contains four (4) discrete zones 250 that are symmetrical within the column 244 about a center line 252. The zones 250A define mounting surface 76 on a foundation 74. The zones 250B correspond to the surfaces 82 provided on the foundation. The' wafer 200" containing the foundations 74 is exposed in a manner analagous to thai shown in Figure 37, wilh the exception that the exception that the solder mask exposure is not carried out. However, the layer of silica is removed from the surface of the wafer 200".

Having prepared wafers for the arms 22A (the wafer 200), the arms 22B (the wafer 200') and the foundations 74 (the wafer 200'^*)_t the final assembly of the connector 120 may be made as is shown in Figure 40.

The wafer 200' is placed on top of the wafer 200. The registration of the features on the wafer 200' to those on the wafer 200 is effected using at least two and preferably four lengths of a strfpped optical fiber and the corresponding appropriate one of the alignment grooves in each array 212 of grooves. The diameter of each length of the optical fiber is measured by micrometer, accurate to plus or minus 0.5 micrometers. Each of the fibers is placed in groove in the groove array 212 that most closely corresponds to the measured diameter. Each alignment fiber thus sits in the selected alignment groove such that the axis of the alignment fiber lies in the plane of the surface of the wafer 200 with the remaining portion of each fiber protrudes above that surface. The wafer 200' is inverted and placed atop the wafer 200, with the corresponding grooves in the wafer 200' receiving the protruding portions of the alignment fibers thereby to precisely align the patlern of ihe two wafers. Since the alignment grooves on each wafer are formed simultaneously with the formation of the features on the wafer, and since the mask for each wafer is formed optically one from the other, precise alignment between the wafers is achieved. It is noted in Figures 40A and 40B only one of the fibers 254 and grooves 121 is shown, for clarity of illustration.

The assembly of superimposed wafers 200, 200' shown in Figure 40A is bonded in a wet controlled atmosphere furnace according to methods described in the paper by Shimbo et al., , "Silicon-to-silicon direct bonding method" published 10/86 in the Journal of Applied Physics, and in the paper by Lasky et al., "Silicon on Insulator (SOI) By Bonding and Etchback", IEDM 85. As seen in Figure 40B the exterior surface 256' of the wafer 200' is lapped to reduce its thickness from it original thickness (typically approximately seventeen (17) micrometers) to a final thickness of five (5) micrometers.

The resulting bonded structure is inverted and the exterior surface 256' of the wafer 200' is mounted atop the wafer 200". The alignment of these wafers is effected using a fixture employing quartz blocks 260 abutting against the flats 201 , 202 of the wafer 200. The wafer 200' is then bonded to the wafer 200". It is to be understood that other bonding techniques, such as those discussed in the paper by Wallis and Pomerantz "Field Assisted Glass-Metal Sealing" published 9/69 in the Journal of Applied Physics may be used to bond the wafers. Still other alternate bonding techniques would include metallic or glass solder bonding. The exterior surface 256 of the wafer 200 is then lapped until the dimension of the wafer 200 is that of the wafer 200'. Thus, the substantial equality of the biasing forces imposed by the flexure is provided.

The resultant three wafer bonded stack shown in Figure 40D may then be cut. Only the top two wafers 200, 200' of the bonded stack (containing ihe arms 22-1 B, 22-2B and the arms 22-1 A, 22-2A, respectively, Figure 22) are first cut along the lines in the wafers corresponding to the cutting lines 230, 230' on the arm masks (Figure 36). This cut is made using a blade that is on the order of 0.003 inches to create the distance 122 in Figure 22. The bonded stack is thereafter cut, using a blade that is 0.015 inches thick, along the lines in the wafers corresponding to the separation lines 227A, 227B on the wafer 200, the separation lines 227 A', 227B' on the wafer ^'200', and the separation lines 248A, 248B on the wafer 200", as well along the scribe lines 226, 226' and 246 (on the respective wafers 200, 200' and 200") all of which are registered with each other, thereby to yield from the bonded stack about one thousand of the fiber-to-fiber connectors 120.

-o-0-o-

Those skilled in the art, having ihe benefits of the teachings of the present invention as hereinabove set forth, may impart numerous modifications thereto.

For example, as seen in Figure 42, in addition to the various embodiments of the two-armed configurations for the positioning apparatus of the present invention previously disclosed, it lies wilhin the contemplation of this invention for a positioning apparatus to exhibit more than two arms 22. In this regard Figures 42A to 42C illustrate a positioning apparatus having Ihwt arms 22A, 22B and 22C while Figures 42D through 42F illustrate a positioning apparatus having four arms 22A, 22B, 22C and 22D. The extension to even greater number of arms would be readily apparent to those skilled in the art.

In Figure 42A each the arms are configured similar to the form of the arms discussed above. The arms may, if desired carry a groove, although il should be understood that such is not required. In Figures 42B and 42E the arms are configured from rods. Although the rods shown as round in cross section . it should be understood that they can have any desired alternate cross section. In Figures 42C and 42F the arms are configured in a generally planar bar form. In Figure 42D the four arms may be formed by sawing the upper and lower arms (indicated by the characters 22A, 22B in Figures 1 to 4) along a cut line extending perpendicular to the major suraces 26 and 28 of each of the arms.

However configured the arms are shown in Figures 42A through 42F as angularly juxtaposed in a surrounding relationship to the channel 92 defined their cooperative association. Similar to the situation described heretofore the resiliency of the arms defines the biasing means which urge the arms toward the closed position. However, il should be understood that the biasing means may be otherewise defined, so long as the force on each arm passes through the reference axis and the sum of forces on ihe arms when they are in the centering position is substantially equal lo zero. Whatever form of biasing means is selected the bias force must increase with deflection of the arm. The arms act against the fiber F inserted into the channel along the various lines of contact LC illustrated in Figure 42 lo maintain the predetermined point on the fiber on the reference axis R. It should be understood that such modifications as herein preented and any others are to be construed as lying within the contemplation of the present invention, as defined by the appended claims.

WHAT IS CLAIMED IS:

Claims

1. A positioning apparatus for positioning a cylindrical member comprising:

at least a first and a second arm, each arm being movable from a first, closed, position to a second, centering, position,

in the closed position the arms cooperating to define a channel having a reference axis therethrough, the channel having an inlet end and an outlet end,

means for biasing each of the arms toward the first, closed, position such that the force on each arm passes through the reference axis and such that the sum of forces on the arms when in the centering position is substantially equal to zero,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with the axis of the member spaced from the reference axis is initially displaceable by contact with at least one of the arms to place a predetermined point on the member into alignment with the reference axis,

the arms being responsive lo further axial movement of the member through the channel by moving against the bias force toward the centering position lo maintain the point on the member on the reference axis.

2. Λ positioning apparatus for positioning a cylindrical member having an outer diameter thereon, the positioning apparatus comprising: 46

at least a first, a second arm and a third arm, each arm being movable from a first, closed, position to a second, centering, position,

means for biasing each of the arms toward the first, closed, position such that the force on each arm passes through the reference axis and. such thai the sum of forces on the arms when in the centering position is substantially equal to zero,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with the axis of the member spaced from the reference axis is initially displaceable by contact with at least one of the arms to place a predetermined point on the member into alignment with the reference axis regardless of the diameter of the cylindrical member,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to maintain the point on the member on the reference axis.

3. A positioning apparatus for positioning a cylindrical member comprising:

a first and a second arm, at leasl the first arm having at least a first and a second sidewall cooperating to define a groove therein, the arms being arranged in superimposed relationship, each arm being movable from a first, closed. position lo a second, centering, position. means for biasing each of the arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with the axis of the member spaced from the reference axis is initially displaceable by contact with at least one of the arms to place a predetermined point on an end face of the member into alignment with the reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to maintain the point on the face of the member on the reference axis by contact between the member and both the first and the second arms.

4. The positioning apparatus of claim 3 wherein the first and the second sidewalls in the first arm cooperate to define a converging groove therein, the channel being partially funnel¬ like in shape over at least a predetermined portion of its axial length.

5. The positioning apparatus of claim 4 wherein the second arm has a planar surface thereon.

6. The positioning apparatus of claim 4 wherein the second arm has at least a first and a second sidewall disposed therein, the first and second sidewalls in the second arm cooperating to define a converging groove therein, the converging groove in the first arm and the converging groove in the second arm cooperating to define the channel, the channel being fully funnel-like in shape over at least a predetermined portion of its axial length.

7. The positioning apparatus of claim 3 wherein the first arm has at least a first and a second sidewall disposed therein, the first and the second sidewalls in the first arm cooperating to define therein a groove having a uniform width dimension throughout its length, the channel being rectangular in cross sectional shape over at least a predetermined portion of its axial length.

8. The positioning apparatus of claim 7 wherein the second arm has at least a first and a second sidewall disposed therein, the first and the second sidewalls in the second arm cooperating to define therein a groove having a uniform width dimension throughout its length, the uniform groove in the first arm and the uniform groove in the second arm cooperating to define the channel, the channel being rectangular in cross sectional shape over at least a predetermined portion of its axial length.

9. The positioning apparatus of claim 3 wherein each arm has a trough disposed therein, the troughs in the arms cooperating to define a guideway for guiding the member therebetween.

10. The positioning apparatus of claim 9 wherein the guideway has an axis therein, the axis of the .guideway being offset from the axis of the channel by a predetermined distance.

1 1. The positioning apparatus of claim 3 wherein biasing means comprises reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure n each arm which, when each arm is deflected by contact with the member, generates a force on each arm to bias each arm toward the closed position.

12. The positioning apparatus of claim 3 wherein each of the first and the second arms includes a irough therein, each trough being disposed on an arm a predetermined distance behind the groove in thai arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel.

13. The positioning apparatus of claim 3 further comprising a foundation, the first arm being mounted to the foundation.

14. The positioning apparatus of claim 6 wherein the first and the second arms are each fabricated from a crystalline material.

15. The positioning apparatus of claim 3 wherein the first and the second arms are each fabricated from a crystalline material.

16. A positioning apparatus for positioning a cylindrical m mpemmhbperr r cnommpnrriicsiinngo <

a first and a second arm, each arm having at least a first and a second sidewall disposed therein, the first and the second sidewalls cooperating to define a converging groove in each arm,

the arms being arranged in superimposed relationship with the converging grooves therein cooperating to define a channel therebetween that is funnel-like in shape over at least a predetermined portion of its length, the channel having an inlet end and an outlet end and a reference axis extending therethrough , the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with its axis spaced from the reference axis is displacable by contact with at least one of the sidewalls of one of the arms to place a predetermined point on an end face of the member into alignment with the reference axis where it is there held by contacl with the first and second arms

each of the first and the second arms further including a trough therein, each trough being disposed on an arm a predetermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel.

17. The positioning apparatus of claim 16 wherein the first and the second arm are each movable from a first, closed, position to a second, centering, position,

the apparatus further comprising means for biasing each of the arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

the arms being , responsive, to further axial movement of the member through . the channel by moving against the bias force toward the centering position lo hold the point on the face of the member on the reference axis by contact between the member and . both the firsl and Ihe second arms.

18. The positioning apparatus of claim 17 wherein the biasing means comprises reduced thickness portion in each of the first and the seccopd arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a restoring force on each arm to bias each arm toward the closed position.

19. The positioning apparatus of claim 16 wherein the arms are fixed wilh respect to each other.

20. The positioning apparatus of claim 19 wherein each arm has a trough disposed therein, the troughs in the arms cooperating to define a guideway for guiding the member therebetween.

21. The positioning apparatus of claim 20 wherein the guideway has an axis therein, the axis of the guideway being offset from the axis of the channel by a predetermined distance.

22. The positioning apparatus of claim 16 wherein the first and the second arms are each fabricated from a crystalline material.

23. A positioning apparatus for positioning a cylindrical member comprising: a first and a second arm, each arm having at least a first and a second sidewall thereon, the sidewalls in each arm cooperating to define therein a converging groove, the arms being fixed in superimposed relationship with the grooves therein cooperating to define a first fully funnel-like channel having a reference axis therethrough, the first funnel-like channel having an inlet end and an outlet end, the arms being arranged such that a cylindrical member introduced into the inlet end of the first funnel-like channel with its axis spaced from the reference axis is displacable by at least one of the sidewalls to place a predetermined point on an end face of the member into alignment with the reference axis where it is there held by contact with the first and second sidewalls of both arms_f each of the first and the second arms includes a trough therein, each trough being disposed on an arm a predetermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel.

24. The positioning apparatus of claim 23 wherein each of the arms has a major surface thereon, a portion of the major surface connecting the first and the second sidewalls and cooperating to define . the groove therein, wherein the converging groove so defined in each arm has a truncated V- shape.

25. The positioning apparatus of claim 24 wherein .the first arm is mounted to a foundation.

26. The positioning apparatus of claim 23 wherein the first arm is mounted to a foundation.

27. The positioning apparatus of claim 26 wherein the first and second arms and the foundation are each fabricated from a crystalline material.

28. The positioning apparatus of claim 24 wherein the first and second arms are each fabricated from a crystalline material.

29. The positioning apparatus of claim 23 wherein the first and second arms are each fabricated from a crystalline material.

30. A positioning apparatus for positioning a cylindrical member comprising: a first and a second arm, each arm having at least a first and a second sidewall disposed therein, the first and the second sidewalls cooperating to define a converging groove in each arm, the arms being arranged in superimposed relationship, each arm being movable from a first, closed, position to a second, centering, position,

means for biasing each of the arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

in the closed position the arms cooperating to define a first fully funnel-like channel having a reference axis therethrough, the first funnel-like channel having an inlet end and an outlet end,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the first funnel-like channel with its axis spaced from the reference axis is initially displaceable by contact with at least one of the sidewalls on one of the arms to place a predetermined point on an end face of the fiber into alignment with the reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position lo hold the point on the face of the member on the reference axis by contact with the first and second sidewalls of both arms.

31. The positioning device of claim 30 wherein each of the arms has a major surface thereon, a portion of the major surface connecting the first and the second sidewalls and cooperating to define the groove therein, wherein the 54

converging groove so defined in each arm has a truncated V- shape.

32. The positioning device of claim 31 wherein the biasing means comprises a reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a force on each arm to bias each arm toward the closed position.

33. The positioning apparatus of claim 30 wherein the biasing means comprises & reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a force on each arm to bias each arm toward the closed position.

34. The positioning apparatus of claim 32 wherein the first arm is mounted to a foundation.

35. The positioning apparatus of claim 31 wherein the first arm is mounted to a foundation.

36. The positioning apparatus of claim 30 wherein the first arm is mounted to a foundation.

37. The positioning apparatus of claim 34 wherein the first and second arms are each fabricated from a crystalline material .

38. The positioning apparatus of claim 32 wherein the first and second arms are each fabricated from a crystalline material .

39. The positioning apparatus of claim 31 wherein the first and second arms are each fabricated from a crystalline material.

40. The positioning apparatus of claim 30 wherein the first and second arms are each fabricated from a crystalline material.

41. The positioning apparatus of claim 30 wherein each of the first and the second arms includes a trough therein, each trough being disposed on an arm a predetermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel.

42. The positioning apparatus of claim 41 wherein the first and second arms are each fabricated from a crystalline material.

43. A positioning apparatus for positioning a cylindrical member comprising:

a first and a second arm, the first arm having at least a first and a second sidewall, the second arm having a surface thereon,

the first and the second sidewalls cooperating to define a groove in the first arm, the first and the second arms being arranged in superimposed relation and being movable from a first, closed, position to a second, centering, position,

means for biasing each of the arms with a substantially equal and oppositely directed biasing force toward the first, closed position, in the closed position the arms cooperating to define a channel having a reference axis therethrough, the channel having an inlet end and an outlet end,

each of ^"the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with its axis spaced from ihe reference axis is initially displaceable by contact with at least one of the sidewalls on the first arm or the surface on the second arm to place a predetermined point on an end face of the member into alignment with the reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls on the first arm and the surface on the second arm.

44. The positioning apparatus of claim 43 wherein the groove in the first arm is a converging groove such that the channel is a partially funnel-like channel.

45. The positioning apparatus of claim 43 wherein the groove in the first arm is*, a uniform width groove such that the channel is rectangular in cross section, each of the sidewalls has an edge thereon, the edges of the sidewalls contacting the member.

.•s 46. The positioning apparatus of claim 43 wherein the biasing means comprises a reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure ^n each arm which, when each arm is deflected by contact with ihe member, generates a restoring force on each arm to bias each arm toward the closed position.

47. A positioning apparatus for positioning a cylindrical member comprising: a first and a second arm, each one of the arms having at least a first and a second sidewall, the first and the second sidewalls cooperating to define a groove in each of the arms, the first and the second arms being arranged in superimposed relation and being movable from a first, closed, position to a second, centering, position,

in the closed position the arms being cooperable to define a channel having a reference axis therethrough, the channel having an inlet end and an outlet end,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the channel with its axis spaced from the reference axis is initially displaceable by contact with at least one of the sidewalls on one of the arms to place a predetermined point on an end face of the member into alignment with the reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls on each of the arms.

48. The positioning apparatus of claim 47 wherein the groove in the firsl and the second arm is a converging groove such that the channel is a fully funnel-like channel.

49. The positioning apparatus of claim 47 wherein the groove in the first and in ihe second arm is a uniform width groove such that the channel is rectangular in cross section, each of the sidewalls has an edge thereon, the edges of the sidewalls contacting the member.

50. The positioning apparatus of claim 47 wherein the biasing means comprises a reduced thickness portion in each of the first and the second arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a restoring force on each arm to bias each arm toward the closed position.

51. A connector for positioning a first cylindrical member with respect to a second cylindrical member comprising: a first positioning apparatus comprising a first and a second arm, each of the first and second arms having at least a first and a second sidewall thereon, the sidewalls in each of the first and second arms cooperating to define therein a converging groove, the first and second arms being fixed in superimposed .relationship with the grooves therein cooperating to define a first fully funnel-like channel having a reference axis therethrough, the first funnel-like channel having an inlel end and an outlet end, the arms being arranged such that a first cylindrical member introduced into the inlel end of the first funnel-like channel with its axis spaced from the reference axis is displacable by at least one of the sidewalls to place a predetermined point on an end face of the member into alignment with the reference axis where it is there held by contact with the first and second sidewalls of both arms, each of the first and the second arms includes a trough therein, each trough being disposed on an arm a predetermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel;

a second positioning apparatus comprising a third and a fourth arm, each of the third and fourth arms having at least a first and a second sidewall thereon, ihe sidewalls in each of the third and fourth arms cooperating to define therein a converging groove, the third and fourth arms being fixed in superimposed relationship with the grooves cooperating to define a second fully funnel-like channel having a reference axis therethrough, the second funnel-like channel having an inlet end and an outlet end, the third and fourth arms being arranged such that a second cylindrical member introduced into the inlet end of the second funnel-like channel with its axis spaced from the reference axis is displacable by at least one of the sidewalls of the third or the fourth arms to place a predetermined point on an end face of the second member into alignment with the reference axis ' where it is there held by contact with the first and second sidewalls of both the third and fourth arms, each of the third and the fourth arms includes a trough therein, each trough being disposed on an arm a predetermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the second cylindrical member toward the inlet end of the channel; and

a foundalion, the first and the third arms being mounted to the foundation with the outlet ends of the first and the second channels being confrontalionally disposed and with the reference axis through the second funnel-like channel aligning with the reference axis through the firsi funnel-like channel.

52. The positioning apparatus of claim 51 wherein each of the first, second, third and fourth arms has a major surface connecting the first and the second sidewalls thereof and cooperating to define the converging groove therein, wherein the converging groove has a truncated V-shape.

53. The positioning apparatus of claim 51 wherein the first, second, third and fourth arms and the foundation are each fabricated from a crystalline material.

54. The positioning apparatus of claim 53 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

55. The positioning apparatus of claim 52 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

56. The positioning apparatus of claim 51 wherein the first, second, third and fourth arms and the foundation are disposed in a housing. *

57. A connector for positioning a first cylindrical member with respect to a sec tod cylindrical member comprising:

a first positioning apparatus comprising a first and a second arm, each arm having^* at least a first and a second sidewall disposed therein, the first and the second sidewalls cooperating to define a converging groove in each arm, the arms being arranged in .superimposed relationship, each arm being movable from a first, closed, position to a second, centering, position,

means for biasing each of the first and second arms with a substantially equal and oppositely directed biasing force toward the first, closed position, in the closed position the arms cooperating to define a first fully funnel-like channel having a reference axis therethrough, the first funnel-like channel having an inlet end and an outlet end,

each of the arms being arranged such that a cylindrical member introduced into the inlet end of the first funnel-like channel with its axis spaced from the reference axis is initially displaceable by contact with at least ont of the sidewalls on one of the arms to place a predetermined point on an end face of the fiber into alignment with Ihe reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls of both arms;

a second positioning apparatus comprising a third and a fourth arm, each of the third and fourth arms having at least a first and a second sidewall thereon, the first and the second sidewalls cooperating to define a converging groove in each arm, the arms being arranged in superimposed relationship, each of the third and fourth arms being movable from a first, closed, position to a second, centering, position,

means for biasing each of the third and fourth arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

in the closed position ihe third and fourth arms cooperating to define a second fully funnel-like channel having a reference axis therethrough, the second funnel-like channel having an inlet end and an outlet end, each of the third and fourth arms being arranged such that a second cylindrical member introduced into the inlet end of the second funnel-like channel with its axis spaced from the reference axis is initially displaceable by contact with at least one of the sidewalls on one of the third or fourth arms to place a predetermined point on an end face of the member into alignment with the reference axis,

the arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering pdsition to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls of the third and fourth arms; and

a foundation, the first and the third arms being mounted lo the foundation with the outlet ends of the first and the second channels being confrontationally disposed and with the reference axis through the second funnel-like channel aligning with the reference axis through the first funnel-like channel.

58. The positioning apparatus of claim 57 wherein each of the first, second, third and fourth arms has a major surface connecting the first and the second sidewalls thereof and cooperating to define the converging groove therein, wherein the converging groove has a truncated V-shape.

59. The posiiioning device of claim 58 wherein the biasing means comprises a reduced thickness portion in each of the first , second, third and fdurth arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a force on each arm to bias each arm toward the closed position.

60. The positioning apparatus of claim 57 wherein the biasing means comprises a reduced thickness portion in each of the first, second, third and fourth arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a force on each arm to bias each arm toward the closed position.

61. The positioning apparatus of claim 60 wherein the first, second, third and fourth arms and the foundation are each fabricated from a crystalline material.

62. The positioning apparatus of claim 59 wherein the first, second, third and fourth arms and the foundation are each fabricated from a crystalline material.

63. The positioning apparatus of claim 58 wherein the first, second, third and fourth arms and the foundation are each fabricated from a crystalline material.

64. The positioning apparatus of claim 57 wherein the first, second, third and fourth arms and the foundation are each fabricated from a crystalline material.

65. The positioning apparatus of claim 60 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

66. The positioning apparatus of claim 58 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

67. The positioning apparatus of claim 57 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

68. The positioning apparatus of claim 57 wherein each of the first and the second arms includes a trough therein, each irough being disposed on an arm a predelermined distance behind the groove in that arm, in the closed position the troughs cooperating to define a guideway for guiding the cylindrical member toward the inlet end of the channel.

69. A connector for positioning a first cylindrical member with respecl lo a second cylindrical member comprising:

a first positioning apparatus comprising a first and a second arm, the first arm having at least a first and a second sidewall, the second arm having a surface thereon,

the first and he second sidewalls cooperating to define a groove in the first arm, the first and the second arms being arranged in superimposed relation and being movable from a first, closed, position to a second, centering, position,

each of the, arms being arranged such that a cylindrical member introduced* into the inlet end of the channel with its axis spaced from the reference axis is initially displaceable by contact with at least one of the sidewalls on the first arm or the surface on the second arm to- place a predetermined point on an end face of the member into alignment with the reference axis,

the arms being responsive to further axial movement of the member throug the channel by moving against the bias force toward the centering position to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls on the first arm and the surface on the second arm;

a second positioning apparatus comprising a third and a fourth arm, the third arm having at least a first and a second sidewall, the fourth arm having a surface thereon,

the first and the second sidewalls cooperating to define a groove in the third arm, the third and the fourth arms being arranged in superimposed relation and being movable from a first, closed, position to a second, centering, position,

means for biasing each of the the third and the fourth arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

in the closed position the third and the fourth arms cooperating to define a second channel having a reference axis therethrough, the second channel having an inlet end and an outlet end,

each of the third and fourth arms being arranged such that a second cylindrical member introduced into the inlet end of the channel with its axis spaced from the second reference axis is initially displaceable by contact with at least one of the sidewalls on the third arm or the surface on the fourth arm to place a predetermined point on an end face of the member into alignment with the second reference axis,

the third and the fourth arms being responsive to further axial movement of the second member through the channel by moving against the bias force toward the centering position to hold the point on the face of Ihe second member on the reference axis by contact with the first and second sidewalls on the third arm and the surface on the fourth arm; and

a foundation, the first and the third arms being mounted to the foundation with the outlet ends of the first and the second channels being confrontationally disposed and with the reference axis through the second funnel-like channel aligning with the reference axis through the first funnel-like channel.

70. The positioning apparatus of claim 69 wherein the groove in each of the first arm and in the third arm is a converging groove such that each of the first channel and the second channel is a partially funnel-like channel.

71. The positioning apparatus of claim 70 wherein the groove in the first arm and in the third arm is a uniform width groove, each of the first and the second sidewalls on each of the first and third arms has an edge thereon, such that the each of the first channel and second channel is rectangular in cross section, the edges of the sidewalls on the first arm and the edges of the sidewalls on the th rd arm respectively contacting the first member and the second member.

72. The positioning apparatus of claim 71 wherein the biasing means comprises a reduced thickness portion in each of the first, second, third and fourth arms, each reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a restoring force on each arm to bias each arm toward the closed position. -

73. The positioning apparatus of claim 70 wherein the biasing means comprises a reduced thickness portion in each of the first, second, third and fourth arms, each reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with the member, generates a restoring force on each arm lo bias each arm toward the closed position.

74. The positioning apparatus of claim 69 wherein the first, second, third and fourlh arms and the foundation are each fabricated from a crystalline material.

75. The positioning apparatus of claim 69 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

76. A connector for positioning a first cylindrical member with respect to a second cylindrical member comprising: a positioning apparatus comprising a first and a second arm, each one of the arms having at least a first and a second sidewall, the first and the second sidewalls cooperating to define a groove in each of the arms, the first and the second arms being arranged in superimposed relation and being movable from a first, closed, position to a second, centering, position,

means for biasing teach of the arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

each of the arms being arranged such that a cylindrical member introduced into the inlel end of ihe channel with its axis spaced from the reference axis is initially displaceable by contacl with at least one of the sidewalls on one of the arms to place a predetermined point on an end face of the member into alignment with the reference axis, 68

Ihe arms being responsive to further axial movement of the member through the channel by moving against the bias force toward the centering position to hold the point on the face of the member on the reference axis by contact with the first and second sidewalls on each of the arms;

a second positioning apparatus comprising a third and a fourlh arm, each one of the third and the fourth arms having at least a first and a second sidewall, the first and the second sidewalls cooperating to define a groove in each of the third and the fourth arms, the third and the fourlh arms being arranged in superimposed relation and being movable from a first, closed, position to a "second, centering, position,

means for biasing each of the third and the fourth arms with a substantially equal and oppositely directed biasing force toward the first, closed position,

in the closed position the third and the fourth arms being cooperable to define a second channel having a reference axis therethrough, the second channel having an inlet end and an outlet end, each of the third and fourth arms being arranged such that a second cylindrical member introduced into the inlet end of the channel with ifs axis spaced from the second reference axis is initially displaceable by contact with at least one of the sidewalls on the third arm or the fourth arm to place a predetermined point on an end face of the second member into alignment with the second reference axis,

the third and the fourth arms being responsive to further axial movement of the second member through the channel by moving against the bias force toward the centering position to hold the point on the face of the second member on the reference axis by contact with the first and second sidewalls on each of the arms; and

a foundation, the first and the third arms being mounted to the foundation with the outlet ends of the first and the second channels being confrontalionally disposed and with the reference axis through the second funnel-like channel aligning with the reference axis through the first funnel-like channel.

77. The positioning apparatus of claim 76 wherein the groove in the first and the third arm is a converging groove such that the and the second channel are each a fully funnel-like channel.

78. The positioning apparatus of claim 76 wherein the groove in the first and in the third arm is a uniform width .groove such that the first and the third channel are each rectangular in cross section, each of the sidewalls has an edge thereon, the edges of the sidewalls in the first and second arms contacting the first member and the edges of the sidewalls in the first and second arms contacting the first member.

79. The positioning apparatus of claim 78 wherein the biasing means comprises a reduced thickness portion in each of the first, second, third and fourth arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with a member, generates a restoring force on each arm to bias each arm toward the closed position.

80. The positioning apparatus of claim 77 wherein the biasing means comprises a reduced thickness portion in each of the first, second, third and fourth arms, the reduced thickness portion defining a flexure in each arm which, when each arm is deflected by contact with a member, generates a restoring force on each arm to bias each arm toward the closed position. 70

81. The positioning apparatus of claim 76 wherein the first, second, third and fourlh arms and the foundation are each fabricated from a ςrystalline material.

82. The positioning apparatus of claim 76 wherein the first, second, third and fourth arms and the foundation are disposed in a housing.

83. A method of aligning predetermined features on a first wafer with predetermined features on a second wafer, each wafer having at least two peripheral areas thereon and a central area in which the predetermined features reside, comprising the steps of:

a) forming a plurality of alignment grooves in both of the peripheral areas of the first wafer simultaneously with the formation of the predetermined features in the central area of the first wafer, each of the alignment grooves having a predetermined depth and width dimension associated therewith, each of the alignment grooves being in a predetermined aligned relationship with respect to the features on the first wafer;

b) forming a plurality of alignment grooves in both of the peripheral areas of the second wafer simultaneously with the formation of the predetermined features in the central area of the second wafer, each of the alignment grooves having a predetermined depth and width dimension associated therewith, each of the alignment grooves being in a predetermined aligned relationship with respect to the features on the first wafer;

c) placing an alignment fiber having a predetermined diameter associated therewith in a selected one of the plurality of alignment grooves in both of the peripheral areas of the first wafer, each selected one of the plurality of alignment grooves having a depth and width dimension corresponding most closely to the diameter of the alignment fiber disposed therein, each alignment fiber protruding a predetermined distance from the alignment groove in which it is disposed; and,

d) superimposing the second wafer on the first such that the corresponding alignment grooves on the second wafer receive the protruding portion of the alignment fibers, thereby to position the predetermined features on the second wafer with the predetermined features on the first wafer.

84. The method of claim 83 wherein the alignment fibers are quartz fibers.

85. A method of fabricating a fiber-to-fiber connector comprising the steps of:

a) forming on a surface of a first silicon wafer a first and a second arm, each of the first and second arms having at least a first and a second sidewall thereon, the sidewalls in each of the first and second arms cooperating to define therein a converging groove having an outlet end, the first and second arms being arranged on the surface of the first wafer such that the outlet ends of the converging grooves are endwise adjacent,

b) forming on a surface of a second silicon wafer a first and a second arm, each of the first and second arms having at least a first and a second sidewall thereon, the sidewalls in each of the first and second arms cooperating to define therein a converging groove having an outlet end, the first and second arms being arranged on the surface of the second wafer such that the outlet ends of the converging grooves are endwise adjacent, 72

c) forming on the surface of a third silicon wafer a foundation having a first and a second mounting area thereon,

d) securing the first and the second wafers in superimposed relationship so that the corresponding first and second grooves on each of the first and second wafers cooperate to define a first and a second fully funnel-like channel, <-.

e) securing the first wafer to the mounting areas on the third wafer such that the first and second channels lie intermediate the mounting areas,

f) severing only the superimposed first and second wafers along a separation line passing intermediate, the outlet ends of the first arid second channels.