The present invention relates in general to connectors and couplers for optical fibers, and more specifically, to connectors and couplers of extremely simple construction which are effective to accurately align and couple individual pairs of optical fibers.
Recently, significant research and development has been extended into the field of optical communication systems, including, but not limited to telephony, data processing, television, and various control applications. The great interest in the use of optical fibers for various communication applications results from the very high available band width, immunity from electro-magnetic interference, communication security, small size, low weight and lack of need for strategic materials. However, the need to efficiently couple such optical fibers, which can be a serious problem due to the extremely small dimensions thereof, provides a serious limitation on the use of such communication waveguides. Thus, connectors and couplers for optical fibers are an important aspect of an effective optical communication system in that they have a direct bearing on the degree of optical losses and the relative ease of installation and maintenance of the system in the field.
Connectors and couplers for optical fibers fall generally into two classes. In a first class, a single coupler is used to interconnect an entire bundle of optical fiber strands. A second class provides a separate coupler to interconnect each single pair of fiber strands. With respect at least to optical communications over substantial distances, the trend has been to employ the single fiber and single fiber connector concepts, primarily because of economic and loss considerations.
In addition, the single optical fiber strand-to-strand connectors and couplers of the prior art have been of generally large size so that use of such couplers in a multi-strand cable of large size may be difficult, if not impossible. One such prior art connector and coupler arrangement is disclosed in U.S. Pat. No. 3,914,880, issued to Dakss et al on Oct. 28, 1975. In the patented arrangement, the end of each optical fiber to be joined is attached within a glass capillary and each glass capillary is inserted into a hollow hard metal plug whose outer surface is ground to a precision diameter. The two metal plugs are then placed in face-to-face relationship in a precision ground V groove formed in a rigid block and are held in place by respective clamping arrangements in which holding screws contact the respective metal plugs and hold them forcefully within the groove so as to maintain alignment between the connectors by virtue of the precision V groove and the precision ground diameter of the respective metal plugs.
The structural arrangement of the connector and coupler combination disclosed in the above-referenced Dakss et al patent clearly is of undesirably large size and of complicated construction rendering it generally undesirable for use in coupling optical fiber strands in a multistrand cable. In addition, the proper alignment between the respective connectors depends in the patented coupler arrangement solely upon the effectiveness of the clamping arrangement associated with the support block in which is provided the precision ground V groove, the respective connectors being held in position on the V groove by separate clamping arrangements. Thus, a loosening of either clamping arrangement during use for any reason can result in a misalignment or uncoupling of the fibers.