Abstract:
An apparatus and method for coupling and decoupling optical leads while preventing twists or kinks in the optical leas as well as back reflections with the apparatus including an a rotatable optical coupler and a non-rotatable optical coupler.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to coupling and, more specifically, to coupling and decoupling optical leads to each other while minimizing reflections and twisting of the optical leads.  
       CROSS REFERENCE TO RELATED APPLICATIONS  
       [0002]     None  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0003]     None  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0004]     None  
       BACKGROUND OF THE INVENTION  
       [0005]     One of the difficulties in optical coupling of the ends of optical fibers to each other is to avoid or reduce the back reflection at the junction between the ends of two optical fibers.  
         [0006]     One of the methods to optically couple two optical fibers, while minimizing back reflections, is to square or dome the ends of two optical fibers and abut the ends against each other and place a gel, or other optical conducting substance, which has an index of refraction that matches the index of refraction of the optical fibers, between the two ends of the optical fibers. Unfortunately, in applications where an optical fiber has to be connected and disconnected the presence of a gel or liquid at the ends of the optical fibers not only hinders the connecting or disconnecting process but it is difficult to retain the optically conducting substance between the ends of the optical leads during the connection and disconnection process. Therefore, a connection and disconnection process using a substance between the ends of the optical fibers, although reducing the back reflection, is generally unsuitable for coupling optical fibers that need to be periodically coupled and decoupled from each other.  
         [0007]     Another method to optically couple optical fibers is angle coupling where angle cut faces are placed in a parallel condition to each other. Angle coupling reduces the back reflection between the ends of two optical fibers. In this method one cuts the ends of each of two optical fibers at a “coupling angle” that is a cut across an optical fiber, at an acute angle with the acute angle such that a reflected optical signal from the optical fiber is directed outside the optical fiber to thereby minimize the effects of back reflection. The method of angle cutting the ends of the optical fibers to produce optical fibers each having an optical end face located at a “coupling angle” and then aligning the optical end faces in a parallel condition reduces the back reflection. Unfortunately, angle cutting the ends also requires one to rotate the optical fibers in order to align the optical faces in a parallel condition to each other. This method of angle coupling is effective in reducing back reflections as well as providing a method wherein the optical fibers can be quickly coupled and decoupled since there is no gel or other substance that needs to be maintained between the ends of the optical leads. However, the rotation of the optical leads to produce alignment of the end faces of the optical fibers can introduce twist or kinks into the optical fibers.  
         [0008]     In order to rotationally align the optical faces during angle coupling one can key the ends of each of the connectors holding the optical fiber so that when the optical fibers are separated and brought together the angle cut faces of the optical fibers are automatically brought into a parallel condition to each other and thereby reduce the loss of an optical signal transmitted across the junction of the angle cut faces. Unfortunately, rotationally aligning the ends of the connectors by rotating one or the other or both of the optical fibers can introduce unwanted kinks and twists into the optical fibers as one rotates the optical fiber to bring the optical faces into an aligned condition.  
         [0009]     The present invention provides a coupling apparatus for optical leads or optical fibers that allows one to quickly coupled and decouple an optical lead and at the same time eliminate the problem of twisting of the optical leads as well as the problem of back reflection at the optical junctions. The present invention uses two optical couplers, one optical butt coupler that remains in a coupled but rotatable condition with minimized back reflections, and another angle optical coupler, that can be quickly coupled or decoupled with the butt coupler including a rotation joint that allows rotation of the optical fibers without introducing twists and kinks in the optical leads.  
       SUMMARY OF THE INVENTION  
       [0010]     Briefly, the present invention comprises an optical coupling apparatus and a method of optical coupling two optical fibers to each other where at least one of the optical fibers to be connected to another optical fiber is severed before the terminal end of the optical fiber to form two butt connectable severed ends in the severed optical fiber. One of the severed ends is mounted in one end of a rotationally member and the other severed end is mounted in the other end of a rotational member so that when the two rotational members are assembled into a rotational coupler the two severed ends of the severed optical fiber are in optical communication with each other though a rotateable butt connection. To reduce the back reflection between the butt connectable severed ends an optical conductive substance having an index of refraction matching the index of refraction of the optical fibers is placed between the two severed ends of the optical fiber. The severed ends of the optical fiber, which are in a butt connecting condition with respect to each other are thus in a condition to rotate with respect to one anther without a degradation of the optical signal therebetween. Thus twist or kinks to the optical fiber are avoided since the rotatable coupling element allows the optical leads to rotate without twisting.  
         [0011]     In order to provide for coupling and decoupling of the optical leads an angle coupler is formed by severing the optical fibers at an acute angle to produce angle cut terminal ends such that any back reflection therefrom falls outside of a optical coupling area between the two severed ends of the optical fibers. In order to rotationally orientate the angle cut terminal ends of the optical fibers an alignment guide is placed on the ends of each of the two optical fibers to allow an operator to rotationally align the angle cut faces of the optical fibers with each other. Thus the presence of the rotational coupler on at least one of the optical fibers allows one to rotate the optical lead without introducing kinks or twists and at the same time maintain the integrity of the optical connection through the optical fibers while the angle cut face alignment coupler allows one to quickly couple or decouple the optical fiber while minimizing back reflections. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a perspective view of a coupler for optically coupling an optical fiber to another optical fiber;  
         [0013]      FIG. 1A  is an end view of the coupler of  FIG. 1 ;  
         [0014]      FIG. 2  is a perspective view of an alignment collar;  
         [0015]      FIG. 3  is a partial cross sectional view showing two optical connectors in a prearranged condition;  
         [0016]      FIG. 4  shows the two optical connectors of  FIG. 3  in an optical transmission mode; and  
         [0017]      FIG. 5  shows a sectional view taken along lines  5 - 5  of  FIG. 1 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     Referring to  FIG. 1  and  FIG. 3 , reference numeral  10  identifies a three part rotatable coupling connector or rotateable coupler secured having one end secured to an optical lead or optical fiber  11 . The rotatable coupler  10  includes a first flanged member  13  secured to the exterior surface of optical lead  11  and a second flanged member  14  located in a rotational relationship with respect to flanged member  13 . Flanged members  13  and  14  are held in rotational engagement and alignment with each other by a U-shaped collar  12  that encompasses the flanges of members  13  and  14 . A reference to  FIG. 3  shows the flanges  13   a  and  14   a  of the flanged members  13  and  14  of coupling connector  10  held in rotational engagement by collar  12  to form a rotational joint.  
         [0019]      FIG. 3  shows two identical rotateable couplers  10  and  30  in a condition for optically coupling optical fibers from two different sources. In the embodiment shown coupler  10  is shown in cross sectional view revealing flange  13   a  and flange  14   a  that are held in a face to face or an abutting condition by a U-shaped collar  12  to permit rotation of member  14  with respect to member  13 . The optical lead  11  is fixed in member  13  and includes a butt connectable terminus or end  11   a  proximate a butt connectable terminus or end  17   b . By butt connectable terminal or end it is meant that the terminal ends have an end face that can transmit an optical signal from one optical fiber to another optical fiber to form a butt coupled joint. To reduce the back reflection, an optical transmitting substance, which has an index of refraction that is substantially the same as the index of refraction of the optical leads  11  and  17  is located between and surrounds the optical leads  11  and  17 . The presence of the optical conducting substance  22  that matches the index of refraction of optical leads proximate the ends  11   a  and  17   b  reduces the optical reflections thereby providing an optical path from one optical lead  11  to the other optical lead  17  or vice versa with a minimum of back reflections.  
         [0020]     Thus a feature of coupler  10  is that the member  14  is rotatable with respect to member  13  without disrupting the optical path from optical lead  11  to optical lead  17  while at the same time inhibiting or reducing back reflections. Coupler  10  also includes a rotational alignment member or elongated key  19  which extends axially along member  14 .  
         [0021]     Positioned proximate to coupler  10  is an alignment sleeve  25  which is shown partially in section. Alignment sleeve  25  has a lumen therein for receiving flanged member  14  and an inner surface  25   a  that mates with outer surface  14   b  of member  14  to coaxially align member  14  within alignment sleeve  25 . Alignment sleeve  25  includes an alignment recess  25   b  that extends in an axial direction from end-to-end of alignment sleeve  25 . The alignment recess  25   b  forms mating engagement with alignment guide  19  to prevent rotation of member  14  with respect to alignment sleeve  25 . Similarly an alignment guide  19 ′ on coupler  30  prevents rotation of member  14   b ′ with respect to alignment sleeve  25 . Thus member  19 , member  19 ′ and alignment sleeve  25  form a non-rotational coupler that maintains the angle cut end faces  17   a  and  32   a  in optical alignment with each other.  
         [0022]      FIG. 1A  shows an end view of member  14  having a centrally located optical fiber  17  having an exposed optical angle cut face  17   a  forming a coupleable end. Optical fiber  17  is fixedly held in member  14  with member  14  having an axially extending alignment member  19  extending radially outward to from a rotational reference guide.  
         [0023]      FIG. 5  shows a cross sectional view taken along lines  5 - 5  of coupler showing optical fiber  17  having an outer surface  17   c  which is secured to member  14  to prevent rotation of optical fiber  17  with respect to member  14 . Thus while optical fiber  11  is fixed with respect to member  13  and optical fiber  17  is fixed with respect to member  14  the optical fibers  17  and  14  are rotateable with respect to each other through the rotational relationship of member  13  to member  14 .  
         [0024]     In the embodiment shown in  FIG. 3 a  second identical optical coupler  30  is shown in cross section positioned proximate the opposite end of alignment sleeve  25 . A first optical fiber  31  is rotationally coupled to a second optical fiber  32  through optical coupler  30 , which is identical to optical coupler  10 , to permit transmission of an optical signal from optical lead  31  to optical lead  32  through a butt coupled junction of optical faces  32   b  and  31   a.    
         [0025]     As can be seen in  FIG. 3  coupler  10  and  30  both carry alignment guides ( 19 ,  19 ′) which can be brought into the alignment recess  25   b  by bringing the ends of coupler  10  and  30  toward each other in alignment sleeve  25 . The alignment sleeve  25  allows the angle cut faces  17   a  and  32   a , which are angle coupleable end faces, to be automatically brought into a parallel relationship, and hence a back reflection inhibiting condition, with each other by merely inserting the end of couplers  10  and  30  into the alignment sleeve  25  and bringing the ends of the couplers into proximity with each other.  
         [0026]      FIG. 4  shows the coupler  10  and coupler  30  located in an optically coupled end-to-end condition while held in rotational alignment with each other by the alignment sleeve  25 . In this condition the optical angle cut face  17   a  and the optical angle cut face  32   a  are in a parallel or substantial parallel condition so as to transmit optical signals from end angle cut face  17   a  to end angle cut face  32   a  or vice versa. In the embodiment shown the angle end faces  17   a  and  32   a  are separated by a gap; however, since the optical faces are at a coupling angle the optical signal can be transmitted from one optical lead to the other optical lead with a minimum of back reflection. The optical angle cut faces  17   a  and  32   a  are referred herein as a “coupling angle cut face”. A coupling angle cut face as referred herein refers to the an angle cut across an optical fiber with the angle of the cut such that a reflected optical signal within the optical fiber is reflected outside the optical fiber so as not to interfere with transmission of optical signals between the two coupling angle cut faces with the angle dependent on the characteristics of the optical fibers.  
         [0027]     While two rotational optical couplers  10  and  30  are shown for rotational connection of optical fiber  11  to optical fiber  31 , a single rotational optical coupler can be used to provide an optical connection and at the same allow one to alleviate any kinks or twists in the optical leads since a single rotatable coupler can alleviate the twist or kinks in two optically connected fibers.  
         [0028]     Thus, in the present invention one can quickly couple and decouple two optical leads to each other while at the same time inhibiting back reflections as well as eliminating kinks or twists in either of the optical leads.