Fiber optic switch configurations

Details Fiber optic switch configurations Fiber optic switch configurations

1999-11-16

2001-11-13

Palmer, Phan T. H. (Department: 2874)

Optical waveguides

With optical coupler

Switch

C385S016000, C385S033000, C385S073000, C385S115000

Reexamination Certificate

active

06317533

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to optical switching and, in particular, to apparatus for selectively coupling the output of one fiber to the input of one of a plurality of other optical fibers.
BACKGROUND OF THE INVENTION
There is a growing need in communications and other applications for redirecting the light from an optical fiber into one or more other fibers on a selective basis. There are a number of commercially available devices which address this need. One of these devices, shown in
FIG. 1
, utilizes graded-index (GRIN) lenses to form a realignable image relay. Light from an input fiber
102
is collimated by a first GRIN lens
104
, which is received by a GRIN lens
106
operative to focus the collimated beam onto an output fiber
108
. The input lens
104
is then mechanically repositioned in alignment with other output lenses and fibers
106
′-
106
′″ and
108
′-
108
′″, respectively, to perform a sequential input-to-output switching function.
One problem associated with the arrangement just described is that each fiber must be held in place relative to its respective GRIN lens through bonding, for example, within an alignment tube. As such, an adhesive is often used between the fiber and the lens, which can degrade under high laser power, thereby adversely affecting performance. In some designs, adhesives are not used in the gap between a particular fiber and its associated GRIN lens, but outgassing from adhesives in close proximity may coat the optical surfaces, causing the same type of problem to occur.
Another existing approach involves alignment of the fiber end faces directly, without the use of bonded lenses. In this case, the fiber end faces are cleaved and polished, and brought to within a few microns and aligned center-to-center. The principle challenge with this approach is the extreme mechanical precision required in the alignment process, such that very small amounts of contamination between the fibers greatly affects performance. In addition, in both of the techniques just described, the fibers are integral to the switch, thereby making removal, reconfiguration and maintenance of the fibers difficult to achieve.
SUMMARY OF THE INVENTION
This invention resides in an improved optical switch of the type wherein the light from an input optical fiber is directed to one of a plurality of output optical fibers on a selective basis. In contrast to existing designs, at least the output fibers are contained in a bundle, preferably within a removable connector, thereby easing removal and maintenance. The input fiber also preferably forms part of a bundle within a removable connector.
Means are provided for selectively directing the light from the end of the input fiber to the end of one of a plurality of the output fibers. In one preferred embodiment, the means for selectively directing the light includes a pivot upon which at least the input optical fiber is mounted. According to an alternative embodiment, an acousto-optic Bragg cell is used for such purpose, thereby eliminating moving parts.
One or more lenses are used between the end of the input optical fiber and the ends of the output fibers to assist in directing the light. A preferred arrangement incorporates two lenses, positioned so that the end of the output fiber and the end of a selected input fiber are each located at the focal point of one of the lenses. When this arrangement is used with a pivoting bench, preferably both the input fiber and a first lens move as the light in directed from input to output.


REFERENCES:
patent: 5165104 (1992-11-01), Weverka

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