WO1996038748A1

WO1996038748A1 - Fibre optic connector having compliant end face

Info

Publication number: WO1996038748A1
Application number: PCT/IB1996/000482
Authority: WO
Inventors: Gerd Schreiter; Andreas Engel; Steffen Reichel
Original assignee: The Whitaker Corporation
Priority date: 1995-05-31
Filing date: 1996-05-22
Publication date: 1996-12-05
Also published as: GB9511010D0; AU5658296A

Abstract

A fibre optic connection component (2) comprising a forward member (18) having a mating face (20) thereupon where the forward member (18) is biased therefrom to bring the mating face (18) into abutting engagement with transmissive face (42) of a mating component (36) for coupling an optical signal therebetween, the connection component (2) being characterized in that the mating face (20) is compliant, whereby the biasing results in the mating face (20) complying to the transmissive face (42) of the mating component (36) to reduce air gaps therebetween.

Description

FIBRE OPTIC CONNECTOR HAVING COMPLIANT END FACE

This invention relates to fibre optic connectors and in particular those connectors that couple an optical signal from a mating component by way of abutment therebetween.

It is common in optical fibre connectors to have the mating components abut one another along their optical axis so that an optical signal may be coupled therebetween. A characteristic of this type of interconnection is that an air gap may exist between the mating components. This air gap leads to fresnel reflections that reduce the overall efficiency of the optical system. One common method that is used to overcome these air gap losses is to minimize any misalignment by assuring a high degree of co-planarity between the mating faces of the mating components. This may be accomplished by providing an optical ferrule having a cylindrical portion and providing a transverse face thereacross which may advantageously be perpendicular. The mating component is then provided with an alignment sleeve to guide the cylindrical ferrule. When the alignment sleeve is perpendicular to the mating face of the component to which it is registered, ideally, the mating faces will be in a co-planar relationship, abutted to one another such that there is no air gap therebetween. As can be imagined, an optical interconnection of this type is difficult to assure due to the high degree of manufacturing accuracies required and the possibility that contaminants, such as dust, would end up between the mating faces.

In order to overcome the afore mentioned difficulties, such that when mating optical faces are positioned close to each other but still have a gap therebetween, it is known to use an optical fluid having the same index of refraction as the transmissive members of the components to be connected. This optical fluid is commonly known as index matching gel and, as the name implies, has a gel-like consistency so that it retains its location. One example of an optical fibre connector utilizing this technology is disclosed in U.S. patent 4,186,998. By filling the gap between the mating components, the losses associated with the fresnel reflections are eliminated. While a construction of this type is very advantageous, it is not without certain disadvantages. It is possible that during installation an installer may forget to include the index matching gel or that during later servicing there may be insufficient gel remaining at the interconnection or contaminants may enter the gel, thereby degrading the interconnection. Finally, in certain environments, it may be possible that over time the gel would be flushed out of the interconnection, thereby degrading the transmission characteristics.

What is needed is an optical interconnection that minimizes any air gap between mating components without the need for the high degree of manufacturing accuracies required by connection systems utilizing co-planarity of mating faces or the necessity of utilizing index matching gel in an interconnection where the manufacturing accuracies have been reduced.

Therefore, it is an object of this invention to provide an optical interconnection where the air gap between mating components is minimized.

It is another object of this invention to provide an economical interconnection where the necessity of high manufacturing accuracies is minimized.

It is yet another object of this invention to provide an optical interconnection that compensates for misalignment and manufacturing inaccuracies without the need for index matching gel.

These and other objects are accomplished by providing an optical component, for example a fibre optic connector, having a- mating face to be transmissively coupled to a mating component characterized in that the mating face is compliant.

It is an advantage of this invention that the optical components do not require a high degree of manufacturing accuracy as the compliant end face compensates therefore, whereby any air gap between the mating components is minimized. It is another advantages of this invention that by eliminating the need for high manufacturing accuracies, a simple and economical optical interconnection may be achieved. It is yet another advantage of this invention that the invention may be incorporated into a fibre optic connector. The invention will now be described by way of example with reference to the drawings wherein:

Figure 1 is a partial side sectional view of a fibre optic connector according to the present invention;

Figure 2 is a side sectional view of a portion of the optical fibre connector of figure 1 positioned above a mating optical component;

Figure 3 is a side sectional view according to Figure

2 showing the portion of the optical connector in its initial mating position; Figure 4 is a side sectional view according to Figure

3 showing the portion of the optical fibre connector in full abutment with the mating component; and

Figure 5 is an enlarged side view of the mating face of the optical fibre connector of Figure 1. With reference first to Figure 1, a fibre optic connector incorporating the present invention is shown generally at 2. The fibre optic connector 2 includes a housing 4 wherein optical coupling elements 6 are disposed. The housing 4 includes channels 8 extending therethrough and separated by a central wall 10. The coupling elements 6 being captively retained within the channels 8, as will be described below. The housing 4 further includes a front mating end 12 and a rear cable exit end 14. The cable exit end 14 may include concave channels- 16 corresponding to the channels 8 such that optical fibres (not shown) may be terminated in the coupling members 6. In the embodiment shown, the channels 16 are incorporated into a radial fibre bend limiter such that the critical radius of the optical fibre is not exceeded as the optical fibres to exit the connector 2 at approximately 90° to the direction of mating.

The coupling element 6 includes a forward optical mating component 18. The forward optical mating component includes a mating face 20 at the end of an extension 22 from the main body portion 24. The main body portion 24 may include a key 26 that would be received within the corresponding slot of the housing 4. The key 26 prevents the component 18 from rotating within the housing 4 and the keys 26 on each of the components may be differently sized in order to polarize the components, for example to keep the input and output lines separate. The component 18 and the channel 8 are configured such that the component 18 may be received within the channel 8 from the rear end thereof such that the mating face 20 extends from the mating end 12 of the housing 4 but the channel 8 is constricted towards the mating face 12 to captivate the mating component 18 therein.. A biasing member 28, in this embodiment a coil spring, acts to bias the component 18 in a forward direction by acting against a rear plug 30 that includes a latch 32 captivated within a window 34 to prevent rearward displacement thereof. Although omitted for clarity, if an optical fibre were terminated, the fibre would extend from within the component 18 where the end face of the fibre would be optically coupled with the mating face 20 of the component 18. The mating component 18 includes a central channel 44 having a bottom 46 for receiving an optical fibre therein and in close proximation with the mating face 20. It may be desirable to use index matching gel within the channel 44 at the fibre face and this would not result in the above mentioned disadvantages as the fibre would not be removed from the channel 44. The fibre would then extend through the biasing member 28 and the plug 30 where it would be disposed within channel 16. A cover (not shown) would then be installed over the rear end 14 to prevent damage to the afore mentioned structure. With reference now to Figure 2, the forward end of the component 18 is shown located above a mating component 36, which in the illustrate embodiment represents active component, such as an LED or laser device. The mating component 36 would include an outer package 38 with a receptacle 40 having a bottom wall 42 from which an optical signal would emanate.

With reference now to Figure 3, as the connector 2 is mated with the structure surrounding the mating component 36 a nose 48 along the mating component 18 is received within the receptacle 40 thereof such that the mating surface 20 comes into contact with the base wall 42. When the connector 2 is fully anchored relative to the complementary member 36 the coil spring 28 acts to bias the mating component 18 against the complementary mating component 36, as shown in Figure 4. As further observed, the mating face 20 complies with the base surface 42 such that any air gap therebetween is eliminated as a result of the spring force F. In order to assure the compliancy necessary, at least a portion of the component 18 that includes the mating surface 20 would be formed of an optical transmissive and compliant material, such as PMMA (plexiglass) or polycarbonate. As shown in the illustrated embodiment, the entire mating component 18 could be manufactured of this material or an insert could be used at the face 20 of the component 18 and affixed thereto by gluing, ultrasonic welding or over oulding, for example.

With reference now to Figure 5, the mating surface 20 is shown in greater detail. The mating surface 20 is tangential to the nose 48 by way of a blend radius 50 that acts to eliminate a sharp edge, thereby easing assembly and preventing damage. The mating face 20 is a modified spheroidal surface having a varying radius from R to r. One particularly advantageous modified spheroidal surface would be a portion of an eclipse, as shown in Figure 5. Furthermore, in the embodiment shown, the centre point C lies along the base 46 of the channel 44 and is disposed at distance r from the mating face 20 along the optical axis O where the distance r corresponds to the radius of the optical fibre. The modified spheroidal surface is especially advantageous in that the force F exerted by the spring biasing member 28 may be resolved into components at the optical face 20 having their largest component corresponding to a direction perpendicular to the mating base wall 42 and requiring a minimal amount of material deformation to approach a generally planer mating surface. It should be appreciated that other profiles may be desirable where the mating face takes on a different configuration.

Advantageously, an optical connection component is provided having a mating end face that is compliant such that when abutting a complementary component the compliancy of the end face corresponds to the complimentary component thereby eliminating an air gap therebetween. The optical connection component minimizes the need for eye-levels of manufacturing accuracy, thereby providing an economical and useful device. Furthermore, by incorporating the compliancy directly into the component is not necessary to include such external material as an index matching gel to fill any of the voids between the mating components in order to reduce the losses therebetween.

Claims

1. A fibre optic connection component (6) comprising a forward member (18) having a mating face (20) thereupon where the forward member (18) is biased forwardly by a biasing member (28) to bring the mating face (20) into abutting engagement with a mating face (42) of mating component (36) , the connection component (6) being characterized in that the mating face (20) is compliant, whereby the biasing results in the mating face (20) complying to the face (42) of the mating component (36) to reduce air gaps therebetween.

2. The fibre optic connection component (6) of claim 1 further characterized in that the mating face (20) is a modified spheroid.

3. The fibre optic connection component of claim 1, further characterized in that the forward member (18) includes a blind channel (44) therein extending from a fibre receiving end to a bottom (46) in close proximity to the mating face (20) , the blind channel (44) configured to receive an optical fibre therein.

4. The fibre optic connection component of claim 2, further characterized in that an optical fibre is received in the forward member (18) to a distance equal to the radius of the fibre (r) , the modified spheroidal surface of the mating face (20) having a continuously increasing radius (r-R) from the radius of the fibre (r) to an outer surface of the forward member (R) (48) .

5. The fibre optic connection component of claim 3, further characterized in that index matching gel is deposited within the blind channel (44) .