Optical waveguides – With optical coupler – Input/output coupler
Patent
1991-09-30
1993-03-09
Lee, John D.
Optical waveguides
With optical coupler
Input/output coupler
385 34, G02B 626, G02B 642
Patent
active
051931320
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an optical fiber coupler utilizing phase space techniques to improve injection and extraction efficiency, methods for making same, and networks usable therewith.
Numerous methods have been proposed in the prior art for distributing information using an optical fiber, preferred methods including star, ring, and bus architectural networks. Numerous methods have also been proposed for coupling light between an optical fiber core and an electro-optic transducer.
Miller, GB 2,126,749B and Dakin et al. "Experimental Studies into the Non-Invasive Collection and Distribution of Data on a Fiber-Optic Monomode Bus" propose designing a read optical fiber bus using couplers whereby light is withdrawn through a side of the optical fiber by passing the light through a coating of the fiber. Miller collects the light from the bus fiber by disposing a photodetector at an end of a curved and grooved light pipe disposed around the bus fiber, and Dakin et al. collects the light by tightly pressing a polymeric fiber with part of its cladding removed against a curved portion of the bus fiber. Such techniques are disadvantageous since the couplers are complicated in design, are difficult to install in the field, and are not sufficiently efficient. Typical fiber optic bus installations have what are called flux budgets. This refers to the amount of energy in the fiber versus the number of couplers. When tight flux budgets are mandated by network design, the inefficiencies of the prior art coupler designs require fewer couplers per bus resulting in fiber optic bus structures being less competitive with conventional technologies.
Goell et al., U.S. Pat. No. 3,982,123 at FIGS. 5A and 5B discloses an optical fiber read coupler whereby an exposed glass cladding of a bent optical fiber portion is glued to a top of a photodetector. Such couplers are disadvantageous since the strength of the fiber is adversely affected by removal of the outer protective buffer. Further, rather small light coupling efficiencies are obtained by simply using epoxy to secure a bent optical fiber onto a top surface of a photodetector. In addition, the optical fiber is not releasable from the coupler.
Cross, U.S. Pat. No. 4,270,839 discloses a coupler for an optical fiber whereby the fiber is bent in air, and downstream from the bent portion of the optical fiber a straight section of the optical fiber is glued within a straight light pipe which thereafter is curved and has a light detector at a remote end thereof. Again, such couplers disadvantageous since they have been found to yield relatively low light coupling efficiencies, and because the optical fiber is not releasable from the light pipe once attached.
Campbell et al., U.S. Pat. No. 4,728,169; Campbell et al., U.S. Pat. No. 4,768,854; Campbell et al., U.S. Pat. No. 4,747,652, and Uken, U.S. Pat. No. 4,741,585 and 4,824,199, the disclosures of which are all incorporated herein by reference, disclose several advantageous kinds of couplers for either injecting light into or withdrawing light from optical fibers.
Gerndt, German Patent Application Number P 24 09 455.1, published Sep. 4, 1975, discloses an optical coupler using a bent fiber and a lens to guide the light emitted from the fiber to a detector. No mention of phase space alteration is made.
There continues to be a need for more efficient couplers which are also mechanically simple in structure, easy to install and easy to maintain.
Accordingly, it is an object of the present invention to eliminate the above-noted drawbacks and to provide an optical method of altering a direction of light propagation using phase space techniques to provide more efficient coupling between two optical devices, one of which is optimally a waveguide.
These and other objects are achieved by utilizing phase space optical techniques to improve coupling efficiency in a coupler which bends an optical fiber waveguide in a plane to enable light emission from the fiber and light injection into the fiber. Preferably the plane of the bend is fla
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Link William T.
Uken William D.
Kovach Dennis E.
Lee John D.
Raynet Corporation
Wise Robert E.
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