CA1143974A - Fiber optic connector for high density applications and method of manufacturing fiber optic connectors - Google Patents

Abstract

FIBER OPTIC CONNECTOR FOR HIGH DENSITY APPLICATIONS
AND METHOD OF MANUFACTURING FIBER OPTIC CONNECTORS

ABSTRACT

The present invention relates to fiber optic connectors and, more particularly, to a fiber optic connector for optically interconnecting two high density sets of optical fibers and a method of manufacturing fiber optic connectors. While prior art fiber optic connectors are available, they are generally limited to connectors for a small number of communication channels. Recently, there has been a growing interest in and recogni-tion of the need for, developing a suitable fiber optic connector for optically interconnecting two high density sets of optical fibers, particularly for single fiber cables, with low loss and minimum cross-talk characteristics. The connector of this invention satisfies this need. The connector includes a pair of connector members each having a rear end and a forward, mating end. It also includes means associated with the forward, mating end of each of the connector members for terminating one high density set of optical fibers, each of the terminating members including means for disposing the optical fibers of one high density set in a predetermined pattern. The connector further includes means for securing the connector members together with the forward, mating ends thereof adjacent. With these features of construction, the connector is well suited for optically aligning two high density sets of optical fibers.

Description

~3~7~
FIBEF~ OPTIC COI~M TOR_O~L~
AND ~IETE:OD OF l~rl~UF~CTURING FI:i3ER OPTI(:: COl`J~ECTOl~S
_ TE~H~ICAL FIELD
The present invention rel~tes to fiber optic connectors and, more particularly, to a fiber optic connector for optically interconnecting two high density sets of optical fibers and a method of manuf~cturing fiber optic connectors.
BACKGROUND OF THE PRIO~ ~T
In recent years, fiber optic communi-cation lines made up of parallel optically-conductive fibers arxanged to form a flexible cable for conveying li~ht ~rom one location to ano~her lS have come into lncreasing use. The applications have varied, althouyh one particularly significant applica~ion has been conveying data from one loca-tion to another by modulatîng a light source with data to be transmitted at one end o$` the cable and recoverin~ the data at the other end of the cable with a photo sensitive detector. Since the data is conveyed by a medium not subject to radio ~requency intererence or detection, fiber optic commun~cation lines are particularly well adapted for applications reauiring a high de~ree of security li~e those found in the data processing ~ield~ ;
r~ith the increasing use of fiber optic~
communication lines, the need has developed for connectors capa~le o joining segments o~ cables with minimum detriment to the optical transmission path. It has been found that precise axial and angular alignment between a pair of fiber optic cables can be achieved by terminating the optical fibers of the cables in connector pin assemblies in such a way that the optical fibers are con-centrically ali~ned with respect to the outer dimension of the connector pins. r~en a pair of connector pins are concentxically aligned, the ~0 ultimate result is that the optical fibers will ~$.`
, :

likewise be angularly and axially aligned for efficient light 'cx~nsferO
Ti~hile tha connector art has been developing-, the primary focus has been upon connec-tors :Eor a small number of channelsO iiore recently, there has been a srowing interest in and recogni-tion of the need for, cleveloping a suitable fiber optic connector for optically interconnecting two high density sets of optical fibers, particularly ~or sinc;le fiber cables. Understandably, this inte.rest has developed out of ~n appreciation for the fac-t that the extremely high c~pacities assoc-iatefl ~ith fiber optic cables can be expanded dramatically by using high density sets or array~
of optic~l fibersO ~Iore particularly, there has been ~n increasing awareness of the clesirability of clevelopin~ ~ fiber optic connactox th~t will expand c2pacity by sever~l or~ers of m~ynitude.
~ddition~lly, fiber optic connectors should exhibit low loss ~nd minimum crosst~lk character-istics.
~lthough the advantages o a fiber optic connector fox high density ~pplic~tions have been ~pp.reciate~, the c~esirabililty an~ neefl has rem~ined ~or ~ pr~ctic~l embodiment~ It h~s not previously been known or sugge~ted how to achieve the yoa~ of a fiber optic connector for optic~lly inter-connecting two high density sets of optical fibers with low loss and crosstalk characteristics~
Accordingly, a practical fiber optic connector for high density applications h~s never before been a.v~ilable even ~hough desirability ~nd need therefor have long been Xnown and appreciatedO
~RIEF SU~ RY OE T~E I~VEMTIOM
Accorclingly, the present invention, in its broadest sense, is clirected to a fiber optic connec~or for high density applications and a method of manufacturing such ~ fibex optic connector. The connector includes a p~ir of connector members e~ch ~3~?~4 ~, having a mating end and means associated with the mating end for terminating one high density set of the optical fibers; the terminating means each including a rela-tively thin alignment plate having a plurality of opti-5 cal Eiber receiving holes disposed in a predetermined :~ :
pattern for receiving individual ones of the optical fibers and a back plate secured to the alignment plate :
to- provide support therefor, the back plate having an enlarged opening of a size at least coextensive with the 10 entire pattern of optical fiber receiving holes, the : :
optical fibers all passing through the enlarged opening to the alignment plate; and means for securing the con~
nector members together with the mating ends thereof adjacent so that the optical fibers of the two high density sets are in optical alignment.
Also in accordance with this invention, there is provided a method of manufacturing a fiber optic connec-tor for optically interconnecting two high density sets of optical fibers, comprising the steps of providing a pair of connector members each having a mating end; pro-viding a thin alignment plate with a plurality of opti-cal fiber receiving holes disposed in a predetermined ;~
pattern for receiving individual ones of the optical .:~
fibers; providing a backplate secured to the alignment 25 plate to provide support therefor with the backplate ;:~:
having an enlarged opening of a size at least coexten-sive with the entire pattern of optical fiber receiving holes in the alignment plate; securing the alignment and backplates in the mating end of at least one of the 3Q connector members; and securing one high density set of optical fibers in the enlarged opening of the backplatè
and the optical fibers of the one high density set in the optical fiber receiving holes in the alignment plate.
More specifically, the connector members preferably each include a connector shell having an opening sized and shaped to accommodate one high density set of opti~
cal fibers extending completely therethrough from the ' :~

3~

rear end to the forward, mating end. The connector shells may each include means integral therewith for ~-providing a sealed connector. The sealing means suit-ably includes means associated with the rear ends and means associated with the forward, mating ends when the connector members are secured together. The terminating means may each include surface means for disposing the optical fibers of one high density set in a predeter-mined pattern. The surface means suitably disposes the optical fibers of the two high density sets in parallel planes. Moreover, the surface means preferably each include an alignment member having optical fiber receiv-ing holes therein defining the predetermined pattern and - -being at least sufficient in number to receive the opti-cal fibers of one high density set.
In one embodiment, the connector preferably includes means associated with at least one of the con~ `
nector members for biasing the terminating means of the connector member forwardly therein. The connector mem-ber then suitably includes stop means to limit Eorward movement of the ~ ~
: ' ,:
; ~ ~

:

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:
, : :

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terminatin~ means caused by the biasing me~ns.
The biasing means is preferably a spring and the stop means a retaining ring with the connector member includiny a ring receiving ~roove for the retainins ring forwardly of the termin~ting means and a sprin~ supportin~ surface for the spring rearwaxdly o the terminating means. The securing me~ns suitably includes a Eirst coupling member associated with one of the connector members and a second coupling membex associated with the other of the connector membersO The first coupling memher is engageable with the second coupling member to secuxe the connectox shells together.
Addi~ion~lly, the securincj means optionally includes~
means for limiting engagement of the fixst~co~pling member with the second coupling member to control saparation of the optical fibers of the two high density sets.
Rdditionall features of this embodi-ment include means for orienting the pair ofconnector members such that the optical fibers of the kwo high density sets are in optic~l alignment when th2 connector member~ ~re secured tagether with the forward, matin~ ends thereof adjacent.
Als~, the orienting means m~y include 2t least two pins associated with the termin~ting means of one of the connector members and a corresponding number of pin receiving openings associated with the terminating means o~ the other of the connector members~
In another embodiment, the fibes optic ;
connector is ~lso well suited for optically inter~
connecting two hi~h density sets of optica~l fibers.
The connector includes a pair of connector shells each having a rear end and a forward, mating end~
and having an opening extending completely there-throu~h from the rear end of the -forward, mating ;
end with the opening in each of the connector shells~
beln~ si~ed and shaped to accom date one high .:

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, ~3~
--5~
density set of the optical fibers. It also includes me~ns associated with the forward m~tincJ
end of each of the connector shells for terminating one high density set of the optical fibers with each of the terminating means including surface means or disposing the optical fibers of one high densi.ty set in a predetermined pa-ttern defined by optical fibex receivinc~ holes in the surface means at least suf*icient in number to receive t.he optical fibers of one high density set. The connector al50 includes means associated with each of the connector shells rearw~rclly o the surf~ce means for providing stress relie~ for the optic~l fibers of one high desnity set ~nd means for securing the connector shells together with the forward, mating ends thereo~
adj~centO t.~.ith these features of construction, the fiber optic connectox ~imilarly optically aliyns the two hl~h density sets of optical ~ibers~
~dditional features oE this embodiment include the connector shells each havin~ means assoclate~ t~erewith for prc,vidincJ a sealed connector~ The sealing means preferabl~ includes ma~ns associate~ with the rear ènds and means associate~ with the forward, mating ends when the connector members are secured tocJether pre-ferably in ~he form of a resilient 0-ring disposed in a circumferentially extending groove in one o-E
the connector shellsO The terminatincJ means prefer~bly each include ~n alignment plate com-prisin~ the surface meens ~nd a backplate disposed rearwarclly of the alicJnment plate to provide support :~
therefor. In addition, the alignment ~lates are preferably secu.red to the backplates.
~/oxe particul~rly, the backplates pre- .
ferably each include an enlarged bore at least :~
coextensive with the corresponding ones o~ the optical fiber receiving holes. The optical fibers of one high density set then pass thxough the enlarcjed bores of each o~ the backpl~tes to the 3~7~

coxxesponding one of the aliynment plates where they are secureclO The terminatiny means suitably includes means for orienting the pair of connector shells such that the optical fibers of the two high density sets are in optical alignment when the connector shells a.re secured together with the for-ward, mating ends thereof adjacent with the orienting means includiny at least two pins associated with the terminating means of one of the connector sheIls and a corresponding number of pin receiving openings associated with the terminating means of the other of the connector shellsO The pins are praferably secured in pin receiving bores in the alignment ~ -plate and backplate of one of the connector shells lS and the aliclnment plate and backplate of the other of the connector shells includes a corresponding number of pin receiving openings. In one embodi-ment, the pin reCeivincJ openings include an ~;
alignment hole and an alignment slot with the align-ment hole and the alignment slot being adapted to receive the pins Eor oriente!d and aligned inter-engacJement of the connector shells.
Other details of this embodiment may include 2 rigid insert in ~t least one connector ~-~
shell secured therein against rearward movement with ~ circumferential groove ~efining a~spring supporting surfaceO The spring supporting surface is provic1ed to support a spring disposed between the rigid insert and the backplate and biasing the backpl~te forwardly within the connector shell against a retaining riny disposed in a ring receiving yroove in the connector shell. It will be ~ppreciated tha~ the rigid insert is therefore preferably spaced rearwardly of the backplate and, also, the optical fibers are preferably free to flex in the reyion between the backplate and the rigid insertO The b~ckplate and alignment plate preferably include a pair of pins coopera$ing with ~;
a pair of slots in the rigid insert to key the : ' : :

terminating means to the connector shell in a manner permitting relative axial movement. Addi-onally, the connector preferably includes spacer means in the form of a planar sheet having an opening therethrough at least coextensive with the optical fiber receiving holes which cooperates with the spri~ly to permit controlled separation of the two high density sets of optic21 fibers, the terminating means being located so as to be in cont~ct with the spacer me~ns when the con nector shells are secured to~etherD
0ther advantageous featltres may in-clude a backplate support member disposed and secured rearwardly of the backplate in each of the connector shells. The terminating means may each include a block having a front face defining the surf~ce means and a rear face with boras extending substantially through the blocks from the rear face toward the front Eace and with the blocks also each having precision ~ormed optical fiber receivin~ holes in the front face in commu-nication with the boresO The connector may also include means for orienting the connector shells in the form o a lip on on~ of the terminating means and a lip receivin~ groove on the other of the terminating means such that the optical fibers ;
of the two high density sets are in optical align~
ment when the lip is disposed in the lip receiving grooveO The stress relief means may incl~e a pottiny compound associated with e~ch of the con~
nector shells with an elastic compound preferably bein~ located adjacent the rear ends thereof and a rigid resin beiny locatecl forwaxd of the elastic compoundD The securing means may include an ~ -internally threaded coupling ring associated with one of the connector shells and an externally threaded surEace associate~ with the other of the connector shells together with optional means for limiting threading engagement of the internally thxe~e~ couPling riny in the externally threadec3 surface to control sepaxation of the optical fibers of the two high density sets. Finally, the precletermined pattern may be defined by at least one row o optical fiber receiviny holes, xnd preferably a plurality of rows and columns of optical fiber receiving holes, the surface means each including a perforated metal alignment pla~e having the rows and columns of optic~l fiber receiving holes therein.
In the method of manufacturing a fiber optic connector for optically intercon-neckin~ two high density sets of optical fibers, the steps are the following. First, a pair of connector members each having a reax end and a forward, mating end are provided. Second, a terminating member for association with the for-ward, mating end of e2ch of the connector member~
is provided. Third, optical fiber receiving holes are placed in each of the terminating members in a predetermined pattern. Fourth, one of the terminating members is secured in the forward, matiny end of each of the connector members. Fifth, the optical fiber~s of one high density set are secured in the optical fiber receiving holes in each of the terminating membersO
Prefera~ly, the termin~ting members are metal and the optical fib~r receiVinCJ hole~ are placed by means of metal etching.
The present invention is therefore directed in its broadest sanse to a fiber optic connector for high density applications and a method of manufacturing fiber optic connectors.
It includes features of construction well suited for optic~lly interconnecting two high density sets of optical ibers using a surprisingly advantageous combination ~nd arrangement o components which make it possible ~o increase the capacity of prior fiber optic connectors by '7~iL
~9 sevexal orders of magnitude~7 Other objects and advantages of the present invention will be appreciatecl from a consideration of ~he detail~
of construction and operation set forth in the accornp~nying specification, c~aims and drawinys.
BRIEF 3~ESC3?~IPTIO~ OF THE DRAWIMGS
The features of the present invention which ~re believed to be novel are set forth with particulaxity in the appended claimsO The inven-tion, to~ether w:ith the further objects and advantayes thereo~, may best be understood b~
reference to the following description taken in conjunction with the accompanying drawings. In the drawin~s, like reference numer21s identify like elements in the several figures in which: ~.
FIGURE 1 is c~ cross-sectional v1ew illu~tratiny a Eiber optic connector fox optically interconnectiny two high density sets of optical fibers in accordance with the present invention ~0 FIGU~E lA is a cros~-sectional view illustrating an alternative embodiment for a connector member constructad in accordance with the present invention;
FIGURE 2 is an enlaryed detailed view of a portion of one of the connector members illustrated in FIGU~E l;
FIGURE 3 is an enlarged detailed vieT~ :
of a portion of the other connector member illus~rated in FIGURE l;
FIGURE 3~ is an enlarged detailed view of a portion of the connector member illustrated in FIGU~E lA
EIGU~E 4 is a front elevational view o~ one form of aliynment pl?te;
I~IGURE 5 is a front elevational view of another form o aliynment plate;
FIGURE 6 is a front elevational view of one ~orm o~ backplate, EIGU3:~E 7 is a front elevational view --10_ of another form of backpl~te;
FIGURE 8 is a front elevational view of an ~lternative embodiment of terminating means;
FIGU~E 9 is a cross-sectional view of an ~ltexnative embodiment of terminating means FIGU~E 10 is an enlarged detailed view of a portion of the terminating means illustrated in FIGU~E 9;
FIGU~E 11 is an enlarged detailed view of a portion of the terminating means illustrated in FIGURE 9, FIGURE 12 is an enlarged detailed view of an alternative embodiment for controlling separation of termlnating means FIGUR~ 13 is a front elevational view, Partially in section, illustratins splice boxes and u~ion splicing useful with fiber opt~c con-nectox~ for optically int~rconnectin~ two hiyh density sets o~ optical fibers in accordance with the pre~ent invention;
~ IGURE la is a front elevational view of ~n alignment pl~te usefu:L with a high density a.rray of optical ~ibers; and FIGUP~E 15 is a front elevational view of ~nother alignment plate useful with a high density arr~y of optical fibers. ;~
DETPILED DESCRIPTIO~ OF THE INVE~TIOM ;~ ;~
With reference first to FIGURE 1, the numer~l 20 designates generally a fiber optic connactor for optically interco~necting two high ;~
den~i~y sets o op~ical ibers in accoxdance with pre~ent inventionD The connector 20 include~
a pair of connector members 22 and 24 having rear ends 26 and 28 and forward, mating ends 30 and 32.
It also includes means 34 and 36, raspectively, ~:
associated with the forward, mating ends 30 and 32 of the connector members 22 and 24 or termin-ating one high density set o optical fiber~ ~such) ~ ;
as 38 ~nd 40, .respectively) with the terminating ~3~

means 3~' and 36 includin~ means ~2 and ~ld for ~isposing the optical fibers o-E one high density set (such as 3a and ~0) in a predetermined pattern~
The connector 20 further includes means 46 for securing the connector members 22 and 24 together with the forward, mating ends 30 and 32 thereof adjacentO With these features of construction, the connector 20 optically aligns the two high density sets 38 and ~0 of optical fibers.
~eferring to FIGURES 2 ~nd 3, the con- ;
nector members 22 and 2~ inclu~e connector shells 48 and 50 having openings 52 ~nd 54 sized and shaped to accommodate one high density set of the optical fibers exten~ing completely therethrough from the rear encls 26 an~ 28 to the forward, m~ting ends 30 and 32. The connector shells 48 ~nd 50 each include means integral therewith for providin~
?, sealed connector includin~ means 56 and 5B
associ~ted rearw~rdly of the forward, mating ends 30 and 32 and means 60 assoc:iated with the orward, mating ends 30 and 32 when 1:he connectox members 22 and 2~ are secured together. The terminating me~ns 3~ and 36 each include surface means ~2 and d4, respectively, for disposing the optioal fibers of one high ~ensity set in a predetermined pattern The surf~ce means 42 and ~4 each include an align~
ment member having optical fiber receiving holes 62 and 6~ (as shown in FIGUP~ES ~ and 5) at least ;
sufficient in number to receive the optical fibers of one high density set. l~îoreover, the surface means ox alignment members 42 and ~a preferably dispose the optical fibers of the two high density sets 3B and ~0, respectively, in parallel planes and ~he predetermined pattern is defined by the optical fi~er receiving holes 62 and 64, respectively, in the alignment members 42 and a~.
Referring to E`IGURE 3, the connector 20 also preferably includes means 66 associated with at least one of the connectox members 24 for 397~ :
_12-biasing the terminating means 36 foxwardly thexein.
The connector member 24 then includes stop means 68 to limit forward movement of the terminating means 36 caused by the biasing means 66 which is preferably a spring with the stop means 68 preferably being a retaining ring. r~Tith this construction, the connector member 24 preferably includes a ring receiving groove 70 for the retaininy riny 68 outwardly of the terminating means 36 and a spring supporting surface 72 for the spring 66 rearwardly of the terminating means 36~
It will be appreciated by referriny to FIGU~E 1 that the securing means 46 preferably ~ ~
includes a first coupling member 7~ associated with ~ -one of the connector members 22 and a second coupling member 75 associated with the other of ;~
the connector members 24. The first coupling ~ ~;
member 74 i~ engageable with the second coupling member 76 to secure the connector shells ~8 and 50 together. ~:loreover, the securing means 46 optionally advantageously includes means 80 for limiting engagement of the first coupling member 74 with the second coupling member 76 and the limiting means 80 thereby optionally comprises means for controlling separ~Ltion of the optical fibers of the two high density sets 38 and 40O
~ eferring again to FIGURES 2 and 3, the connector members 22 and 24 pre~erably include means 82 ~or orienting the pair of connector members such that the optical fibers of the two high density sets 38 and ~0 are in optical alignment when the connector members are secured together with the forward, mating ends 30 and 32 thereof adjacent. In a preerred embodiment, the orienting means 82 includ~s at least two pins 8A~
associated with the terminating means 36 of one of the connector members 24 and a corresponding number of pin receiving openings 86 associated with the terminating means 34 of the other of the .' ~3~74 -1?.-connector members 22.
In a somewhat more specific sense, the connector 20 includes means 88 and 90 associated with the connector shells 48 and 50 rearwardly of the surface means 42 and 44 or providing stre~s relief for the optical fibers of one high density set (such ~.5 38 ~nd 40). The stress relief means 88 and 90 preferably include a potting compound ~ssociated with each of the connector shells 48 and 50. ~ pottin~ compound suitably cooperates with e~ch of the connector shells 48 and 50 and preferably includes an elastic compound (such as 88~ ancl 90' associated with the rear ends 26 and 28, respectively, thereof and a rigid resin 88'' and 50'' forward of the elastic compound 88' and 90', respectivelyO The stress relie means 88 and g0 can also be utilized to secure the components together in sealed relationship within the con-nector members 22 and 24. As will be appreciated from FIGIIR~ 1, the elastic compound 88' cooperates with the rear end 26 of the connector member 22 and the elastic compound 90' coopexates with the re~r end 28 of the connector member 2~ and, more particularly, with the retaining nut 92 to captivate the components within the connector members 22 ~nd 24, respectively.
P~eferring still again to FIGURES 2 and 3, the texminating mean~ 34 and 36 include ali~n~
ment plates 42 and ~-~4 and back plates 94 and 96.
~ith alignment plates ~2 and 44 comprising the ;~
surface means and the back plates 94 and 96 being disposed rearwardly of the alignment plates 42 alld 44 to provide support therefor. The back plates 94 and 96 include enlarged openings 98 and 100 (see FIGURES 6 and 7) at least coexten-sive with the corresponding ones of the optical fiber receiving holes 62 and 64 illustrated in EIGU?~ES 4 and 5, respectively. i~loreover, the optic~l fibers of one hi~h density set ~such as 3~
--l~t 38 or ~.0) pass through the enlargecl opening 98 or 100 of the b?ck plate 94 or 96 to the corresponding one of the alignment plates ~2 and 44, which are secured to the back plates 94 and g6 with the optical ~ibers, in turn, being secured to the alignment plates.
As will be appreciated, the aliynment plate ~.4 and back plate 96 of one of the connector shells 50 include at least two pin receiving bores 102 with the pins 8~ being secured therein and the alignment plate ~2 and back plate 94 of the other of the connector shells ~.8 include 2 corresponding number of pin receiving openings 86.
Preferably, the pin receiving openings 86 include an a:Lignment hole 86' and an alignment slot 86'' in the alignment plate ~'2 and back plate 94 of the connector shell 48 with the allgnment hole 86' and the alignment slot 86'' being adapted to receive the pins 84 for oriented and aligned interengage-~0 ment of the connector shells 48 and 50.
Reerring specifically to FIGURE 3, the connector shell 50 can include therein a rigid insert lO~i-. The rigid inse!rt 104 is preferr~bly secured within the connector shell 50 against rer-ward movement (as shown in FIGU~E 1). The rigid insert 104 still ~urther prefer~bly has a circum-ferential ~roove 106 defining the spring supporting surface 72 (as shown in FIGURE 3)O The rigid insert 10~ is further preferably spaced rearwardly of the backplate 96 with the optical fibers ao being free to flex in the region between the back-plate 96 and the rigicl insert 104 (as shown in FIG~.~ES 1 and 3)~ The rigicl insert 104 still further prefera~ly includes a pair of slots 108 and 110 to cooperate with the pins 84 or keying the terminating means 36 to the connector shell 50 in a manner permitting rel~tive axial movement (as shown in l~IGURE 3). The rigid insert 104 also includes ?. circumferential groove 112 '7~
surrounding cpening 11~ for receiving a resilient sealing grommet or 0-riny 580 l~ith the optical fibers of each high density set 38 ~nd ~0 being disposec3 in fiber optic cable 116 and 118 having S outer jackets 120 and 122, respectively, the opening 11~1 in the rigid insert 104 is of sufficient dia-meter along at least a portion of its length to receive the outer jacket 122 of the fiber optic cable 118 and the grommet or 0-ring 58 cooperates with the outer jac]cet 122 of the fiber optic cable 118 to form a seal~
As best shown in FIGU~E 3, the connector 20 includes spacer means 124 associated with at least one of the alignment plates d;40 The spacer means 12~ cooperates with the biasing means or spring 66 to permit cont~olled separation of the two high clensity sets 38 and 40 oE optical fibers.
The terminating means 3~' c~nd 36 are preferably located so ~s to be in cont:act with the spacer means 12~ when the connector shells ~8 and 50 are secured tocJether. The spacer means 124 in-cludes a planar sheet securecl to one of the alignment plates ~ and having an opening there-through (not shown) at least coextensive with the optical iber receiving holes tsuch as 64). In the altern~tive, the pl~nar sheet 124 can be a transparent film separator in which case no opening is required in the area of the optical fi~er receiving holes~
~e~exring to FIGU~E 2, the connector 20 can include means 128 for supporting at least one of the backpl~tes 940 The supporting means 12~ is preferably a back plate support member disposecl rearwarclly of the backplate 9d. lt will be appreciated that the backplate support member 128 illustr~ted in FIGU~E 2 is a ~enerally cy---lindrical member just aclapted to fit within the opening 52 in the connector shell housing the rigid resin 88''~ The back plate support member t;i~

128 prefer~bly includes a pair of diametrically opposed holes 130 directly in line with ~ pair o~
diametrically opposed holes 132 in the connector shell 48 with this construction, the backplate support member 128 can be secured within the con-nector shell a;8 by means of pins 13~.
R~ferring to FIGUP~ES lA and 3A, an alternative embodiment to the connector member 24 of FIGURES 1 and 3 is fully illustrated. The connector member 24' is entirely identical to the connectox member 2~ with one important difference.
It will be ~ppreciated that the biasing means or spring 66 of FIGURES 1 and 3 has been eliminated in FIGURES lA and 3A in favor of a rigid con-struction. The connector member 24' thereforeincludes a somewh~t different shaped rigid insert 104' in the alternative embodimentO ~iore par-ticularly, the rigid insert 104' is disposed between an internal shoulder 136' in the con-nector shell 50' ~nd the back plate 96'.
As will be appreciated, the back plate96' ~nd the ri~id insert 10~' are maintained in the connector shell 50' by means of the retaining ring 68'~ The back pl~te 96' and the rigid insert 10A' are sized and shaped so as to fit snugly together .in the connector shell 50' ~gainst the intern~l shoulder 136'. It will be appreciatecl in contrast that the back plate 96 and the rigid insert 104 of the embodiment illustrated in FIGURES 1 and 3 ~re spaced with the riyid insert 104 in abutment with the internal shoulder 136 in the connector shell 50. The rigid insert 10~' is in ~butment with the back plate 96' to provide rigidity. ~ccordingly, the connector member 2~' provides a distinct alternative to the connector member 2~l employing the same basic techniques for high density applications.
Other details of the embodiment o-f FIGURES 1~'~ and 3A are generally the same as the ~3~7~

embodiment of FIGU~S 1 and 3 with minor exceptions~
One exception is the shape of the ricJid insert 104' which includes a major diameter opening 13B an~ a minor diameter opening 140. The major diameter opening and the minor diameter opening are filled with rigid potting resin to secure the set of o~tical fibers 40' for a substantial distance rear-wardly of the back plate 96~. Another exception is the location at which the outer jacket 122' is trimmed from the set of optical fibers 40' rear-wardly of the rigid insert 104'~ l~ith this construct.ion, the fiber optic cable 118' is fully secured within the rigid potting resin rather than in the ri~id insert 104~o Referriny ag-ain to FIGURES 2 and 3, the enlarged openings 98 and 100 are shown fillad with epoxy at 142 and la4. This secures the sets of optical fibers 38 and 40 within the back plates 94 and 960 It will. be appreciated that the alter~
native shown in F'IGUP~ES 1~ and 3A al50 includes an enl~rged opening 100' filled with epoxy at 14~s~
in the back pl~te 96'~ similarly to secure the set of optical fibers '~O' w.ithin the back plate 96'. This provides support for the set of optical fibers 40' at a point immediately rearward of the align~ent member 4A I, of course, the epoxy at 142 and 1~ in FIGUP~ES 2 and 3 provide support for the ~ets of optic~l fibers immediately rear~
wardly of the ali~nment members a2 and 4~.
Ps indicated, the sets of optic~l fibers 38 and 40 are secured within the back plates 94 and 96 with epoxy at 142 and 144~ This provides support for the optical fibers within the en-lar~ed bores 98 and 100 in the back plates 94 and 96 ~nd the epoxy provides stress relief for th~ optical fibers. Moreover, the optical fibers in each of the sets 38 and ~0 are secured to the respective alignment members or plates 42 and d4 within the optical fiber receiving holes 62 and 64 7'~a by me~ns of epoxy.
Referring to FIGURES 8 through 10, an alternative embodiment of terminating means is illustrated~ The terminating means 146 and 1~-8 include blocks having front faces 150 and 152 defining the suxace means. The blocks 1~6 and 1~8 also include rear portions or faces 154 and 156 and have bores 158 and 160 extending sub-stan~îally therethrough from the rear faces 154 and 155 towarcl the front faces 150 and 1520 The blocks 146 and 1~8 further have precision-formed optical fiber receiving holes 162 and 16~ (see FIGU~E 10) in the front faces 150 and 152 in communication with the bores 158 ancl 1600 i~ore-over, the bores 158 and 160 may include large diameter portions 158' and 160' and intermediate diameter portions 158'' ancl 160'' leading very nearly to the front faces 150 and 152 in which the precision formed optical fiber receiving holes 162 ~nd 16~ are made.
~eferring to FIGURES 9 and 11, means 166 for orienting connector shells is illustrated.
The orienting means 166, which is ~n alternative to the pins ~a and pin rec~iving openings 86 illustrated in FIGU~ES 2 and 3, can inclu~e a lip 168 on one of the termin~ting means 148 and a lip receiving groove 170 on the other of the ~erminating me2ns 1~6. r~ith this construction, the optical fibers of the two hiyh density sets 38 ~nd 40 are in optic~l alicJnment when the lip 168 is dispose3 in the lip receiving groove 170 and the lip 16a ~ :
~nd the lip receiving groove 170 can be dimensioned so as to create a gap 172 between the terminating means lar6 and 1~8 to control separation between the optical fibers of the two high density sets 38 and -~=0.
l`eferring to FIGU~E 12, an alternative means of controlling separation of the optical fibers of two high density sets 38 and 40 is illustrated ~3~7g~

in enlarged detailO This may be substitutecl for the lip 168 and lip receiving groove 170 arr~nge-ment in FIGU~E 11. It simply includes utilizing a t.ranspaxent film 174 ~etween the terminating means 146 and 1~.8. This does not, however, provide means for aligning the precision formecl optical fiber receiving holes 162 and 164 in the front faces 150 and 152 of the blocks 146 and 148. :
~ccordinyly, other means such as those previously discussed could be utilized to accomplish this objective.
~eferring once again -to FIGURE 1, the securing means 46 preerably includes an inter-n~lly threaded coupling ring 74 associated with one of the connector shells ~8 and an externally threaded surf~ce 76 associated with the other of the connector shells 50. The internally threaded coupling rin~ 74 is ~uitably threaclingly engage-able with the externally threaded surface 760 It will be appreciated that -the securing means ~6 may urther include means for limiting threaded enga~ement o the internally threaded coupling ring 74 and the externally threaded surface 76.
The limiting means 80 comprises means or con-2S trolling separa~ion of the optic~l fibers o ~he two high density sets 38 and ~0. More particu~
larly, the limiting means can optionally comprise proper dimensioning oE the forward ends of the ~ ~
connector members 22 and 24 so that the surface : ;
176 of the connecto~ member 24 will engage the surface 178 o~ the connector membex 22 to control separation of the alignment members or plates 42 and 4~
F~eferring to FIGURE 13, the optical fibers of each o~ the sets 38 and ~0 can suitably be terminate~ in a splice box 180. The splice box 1~0 includes openings 182 at each encl thereof for receiving the optic21 fibers of a fiber optic cableO It will also be ap~reciated that the : ~ ::

3~

splice box 180 includes tu~ulax extensions 184 throu~h which the optical fibers pass into the splice box 180 for fusion splicing. The tubular extensions 184 cooper~te wi-th crimp rings 185 to crimp the outer jacket of the iber optic cable so as to provide stxain relief. I~ith these fe2tures of construction, the splice box makes it possible to easily fusion splice optical fibers in a fashion protecting the splice joint.
l~ore particularly, the splice box 180 permits factory termination of the most critical components. It will be appreciated that the fiber optic connector 20 can be fully assembled with fiber optic cables 116 and 118 terminated in the connector members 22 and 2~1. The splice boxes 180 can be applied to the ends of the fiber optic cables 116 and 118 remote from the connector members 22 and 2~1 to link the fiber optic cables 116 ancl 11~ to much longer runs of fiber optic cable depending upon -the requirement of any particular applicationO It will be appreciated that this permits maximum quality control in the hiyhly critical assembly and termination of high clensity sets o optical fibers. ~ccordingly, the splice box 180 adds a measure of versatility to the fiber optic connectors of the present invention.
Referring to FIGURES 4 and 5, the pre- ;
determined pattern is defined by at least one row of optical fiber receiving holes 62 and 64. The invention is particularly advantageous, however, for predetermined patterns defined by a plurality of rows and columns of optical fiber receiving holes 62 and 6~ as illustrated in F'IGURES 14 and 15 where eight rows and eight columns have been illustrated purely for purposes of illustration since the exact number of rows and columns may be varied depending upon the needs of a particular application~ Prefer~bly, the surface means a2 and 4~ include pexforated metal alignment pl~tes havincJ the rows an~ columns oE optical fiber receivincJ holes thereinO
In the method of manufacturing a fiber optic connector for optically interconnecting two high density sets of optical ~ibers, the steps o optical -fibers, the steps are -the following.
First, ~ pair of connector members each having a rear encl and a forward, mating end are provided.
Second, a terminatinCJ member for association with the forward~ mating end of e~ch of the connector members is provided~ Third, optical Eiber re-ceiving holes are placed in each of the termin-a~ing members in a predetermined patternO Fourth, one of the t~rminating members is secured in the forward, mating encl of each o~ the connector members~ Fifth, the optical fibers of one high density set are secured in the optical fiber re-ceiviny holes in each of the terminating members.
Preferably, the terminating members are metal and the optical fiber receivincJ holes are placed by means of metal etching.
I~ith the fiber optic connector Eor high clensity applications of the present invention, it is possible to provid~ a fi~ler p~cking density capable of being expanded to hundreds of channels within the internal configuration of standard hardware fittingsO The loss at the connector interface and the maximum cross-talk between channels is extremely low. ~eans of splicin~ pig-~ailed connector assemblies into the cable runsis avail~ble as is means of potting the fiber~ into standard hardware fittincjs. The loss at the con-nec-tor interface can be further reduced by optical anti-reflection coatings of the factory terminated 3S interfacesO l?hile threadecl couplings have been illustrated, it is, o~ course, fully contemplated that other couplincJs such as bayonet lock hardware can be utili~ed with this invention.
r~ith respect to the connector interface, ~3~

the a:LicJnment members or plates are highly effective.
These plates are sultably very thin precision st~inless steel with the fiber array holes, the pin alignment holes and the slots being precisely fabricatedO The connector members can suitably be supplied with one meter lenyth pig-tails for fusion splicing into a cable harness. By so doing, E~ctory fabric~tion is ~ossible to locate the most critical ~ssembly and inspection operations at the location of maximum talent leaving only the fusion splice operatioll for field personnel.
ith the alternative embodiment illustrated in ~IGVRES 8 through 12, the production of a mating face c~n be accomplisheæ according to the following stepsO First, a photolithocJraphic mask of a fiber optic ?rray is prep~red. Second 2 plate of a basic material (for ex2mple~ copper) is machined. Thircl, the plate is drille~ with yuide holes in the back of the plate vesy nearly to the front of the plate.
2Q Fourth, the front o~ the plate is then lapped to a mirror Einish and the photolithographic mask is usecl to deposit an absorptive material upon it.
Fifth, ~ l~ser drill is ocused upon the darkened are~s o~ ~he absorptive material to burn through ~5 the remainder o-f the pl2te from the front surface until the holes drilled from the front and rear surf~ces are in communicationO t~hile it is expected that the holes drillecl from the front surface and from the rear surf~ce will not share mutual axes, the misalignmen~ will not be gre~t enough to pre-clude the fibers being inserted -from the rear to be yuided through the front of the plateO
With the various concepts and techni-ques set forth herein, a fiber optic connector for high density ~pplications and 2 method o manu-facturincJ fiber optic connectoxs are provided.
The present invention includes features of constr-uction well suited for optically interconnecting two hiyh density sets o~ optieal fibers usiny 2 ~3~
;:
~23-surprisingly advantayeous combination and arranye-ment of components and alternatives thereto which make it possible to increase the capacity of prior ~ ~
fiber optic connectors by several orders of magni- ~-5 tudeO Accordingly, it will be appreciated that the yoal of providing a fiber optic connector for high density 2pplications approaching the loss and cross-talk characteristics which are essential in fiber optics has been accomplished.
While in the foregoing specification a detailed description of the inventive concepts has been set forth for purposes of lllustration, the details herein given may be varied by those skilled in ~he art without departiny from the spirit and scope of the invention set forth in the appended claims. ~ ~ ;
~, . ::
~ : ~: .:

: ~: ::

~, :

Claims (32)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fiber optic connector for optically inter-connecting two high density sets of optical fibers, comprising:
a pair of connector members, each having a mating end and means associated with said mating end for terminating one high density set of said optical fibers; said terminating means each including a relatively thin alignment plate having a plurality of optical fiber receiving holes disposed in a predetermined pattern for receiving individual ones of said optical fibers and a back plate secured to said alignment plate to provide support therefor, said back plate having an enlarged opening of a size at least coextensive with said entire pattern of optical fiber receiving holes, said optical fibers all passing through said enlarged opening to said alignment plate; and means for securing said connector members together with said mating ends thereof adjacent so that said optical fibers of said two high density sets are in optical alignment.

2. The fiber optic connector as claimed in Claim 1 wherein said connector members each include a connector shell having an opening extending completely therethrough from said rear end to said forward, mating end, said opening being sized and shaped to accommodate one high density set of said optical fibers.

3. The fiber optic connector as claimed in Claim 2 wherein said connector shells each include means associated therewith for providing a sealed connector, said sealing means including means associated with said rear ends and means associated with said forward mating ends when said connector members are secured together.

4. The fiber optic connector as claimed in Claim 3 wherein said sealing means includes a resilient O-ring associated rearwardly of said forward, mating end of at least one of said connector shells and a resilient O-ring associated with said forward, mating ends when said connector shells are secured together, said resilient O-rings each being disposed in a cir-cumferentially extending groove.

5. The fiber optic connector as claimed in Claim 2, further including means associated with each of said connector shells rearwardly of said surface means for providing stress relief for said optical fibers of one high density set.

6. The fiber optic connector of Claim 5 wherein said stress relief means includes a potting compound associated with each of said connector shells.

7. The fiber optic connector of Claim 6 wherein said potting compound is disposed within each of said connector shells and includes an elastic compound adjacent said rear ends thereof and a rigid resin forward of said elastic compound.

8. The fiber optic connector as claimed in Claim 1 wherein said optical fibers are supported within said enlarged openings in said backplates with epoxy, said epoxy providing stress relief for said optical fibers, said optical fibers being secured to said alignment plates with epoxy.

9. The fiber optic connector of Claim 1 wherein said terminating means includes means for orienting said pair of connector shells such that said optical fibers of said two high density sets are in optical alignment when said connector shells are secured together with said forward, mating ends thereof adjacent.

10. The fiber optic connector of Claim 9 wherein said orienting means includes at least two pins associated with said terminating means of one of said connector shells and a corresponding number of pin receiving openings associated with said terminating means of the other of said connector shells.

11. The fiber optic connector of Claim 10 wherein said alignment plate and backplate of one of said connector shells includes said two pin receiving bores, said pins being secured in said pin receiving bores and wherein said alignment plate and backplate of the other of said connector shells in-clude said corresponding number of pin receiving openings.

12. The fiber optic connector of Claim 11 wherein said pin receiving openings include an alignment hole and an alignment slot in said alignment plate and said backplate of the other of said connector shells, said alignment hole and alignment slot being adapted to receive said pins for oriented and aligned interengagement of said connector shells.

13. The fiber optic connector of Claim 9, wherein said orienting means includes a lip on one of said terminating means and a lip receiving groove on the other of said termin-ating means, said optical fibers of said two high density sets being in optical alignment when said lip is disposed in said lip receiving groove.

14. The fiber optic connector of Claim 1 including means associated with at least one of said connector shells for biasing said terminating means forwardly therein, said connector shell including stop means to limit forward movement of said terminating means caused by said biasing means.

15. The fiber optic connector of Claim 14 wherein said biasing means is a spring and said stop means is a retaining ring, said connector shell including a ring receiving groove for said retaining ring outwardly of said alignment plate and a spring supporting surface rearwardly of said back-plate.

16. The fiber optic connector of Claim 15, including a rigid insert in said at least one connector shell, said rigid insert being secured within said connector shell against rear-ward movement, said rigid insert further having a circum-ferential groove defining said spring supporting surface.

17. The fiber optic connector of Claim 16 wherein said rigid insert is spaced rearwardly of said backplate, said optical fibers being free to flex in the region between said backplate and said rigid insert.

18. The fiber optic connector of Claim 16 wherein said rigid insert includes a pair of slots and wherein said backplate and alignment plate include a pair of pins, said pins keying said terminating means to said connector shell in a manner permitting relative axial movement.

19. The fiber optic connector of Claim 16, wherein said optical fibers of each high density set are disposed in a fiber optic cable having an outer jacket, said rigid insert having an opening extending completely therethrough, said open-ing in said rigid insert being of sufficient diameter along at least a portion of its length to receive said outer jacket of said fiber optic cable.

20. The fiber optic connector of Claim 19 wherein said rigid insert includes a circumferential groove surrounding said opening for receiving a resilient sealing grommet, said grommet cooperating with said outer jacket of said fiber optic cable to form a seal.

21. The fiber optic connector of Claim 14 including spacer means associated with at least one of said alignment plates, said spacer means cooperating with said biasing means to permit controlled separation of said two high density sets of optical fibers, said terminating means being located so as to be in contact with said spacer means when said connector shells are secured together.

22. The fiber optic connector of Claim 21 wherein said spacer means includes a planar sheet secured to one of said alignment plates, said planar sheet having an opening therethrough at least coextensive with said optical fiber receiving holes.

23. The fiber optic connector of Claim 1 including means for supporting said backplates, said supporting means including a backplate support member disposed rearwardly of said backplate in each of said connector shells, said backplate support members being secured to the respective ones of said connector shells.

24. The fiber optic connector of Claim 1 wherein said predetermined pattern is defined by at least one row of optical fiber receiving holes.

25. The fiber optic connector of Claim 24 wherein said predetermined pattern is defined by a plurality of rows and columns of said optical fibers receiving holes.

26. The fiber optic connector of Claim 25 wherein said alignment plate is metallic in said rows and columns.

27. The fiber optic connector of Claim 1 wherein said securing means includes a first coupling member associated with one of said connector members and a second coupling member associated with the other of said connector members, said first coupling member being engageable with said second coupling mem-ber to secure said connector shells together.

28. The fiber optic connector of Claim 27 wherein said securing means further includes means for limiting engagement of said first coupling member with said second coupling member, said limiting means comprising means for con-trolling separation of said optical fibers of said two high density sets.

29. The fiber optic connector of Claim 27 wherein one of said coupling members is an internally threaded coupling ring and the other one of said coupling members is an externally threaded surface on the other of said connector members said internally threaded coupling ring being threadingly engageable with said externally threaded surface.

30. The fiber optic connector of Claim 29 wherein said securing means -further includes means for limiting threading engagement of said internally threaded coupling ring and said externally threaded surface, said limiting means com-prising means for controlling separation of said optical fibers of said two high density sets.

31. The fiber optic connector of Claim 1 wherein said optical fibers of each high density set are terminated in a splice box.

32. A method of manufacturing a fiber optic connector for optically interconnecting two high. density sets of optical fibers, comprising the steps of: providing a pair of connector members each having a mating end; providing a thin alignment plate with a plurality o optical fiber receiving holes disposed in a predetermined pattern for receiving individual ones of said optical fibers; providing a backplate secured to said alignment plate to provide support therefor with the backplate having an enlarged opening of a size at least coextensive with the entire pattern of optical fiber receiving holes in said alignment plate; securing said alignment and backplates in said mating end of at least one of said connector members; and securing one high density set of optical fibers in said en-larged opening of said backplate and said optical fibers of said one high density set in said optical fiber receiving holes in said alignment plate.
330 The method of claim 32 wherein said thin align-ment plate is metal, and said optical fiber receiving holes are placed by means of metal etching.