Optical waveguides – With optical coupler
Reexamination Certificate
2000-03-14
2001-10-16
Kim, Ellen E. (Department: 2874)
Optical waveguides
With optical coupler
C385S038000, C385S039000, C385S123000
Reexamination Certificate
active
06304688
ABSTRACT:
BACKGROUND OF THE INVENTION
In optical fiber communication systems, and optical fiber light transmission systems generally, it is typically important to increase the efficiency with which light from a source is coupled into the fiber. One of the most common applications is in communications systems to couple light from a single-transverse-mode light source, e.g., semiconductor laser, into a single-mode optical fiber. Historically, there has been a trade-off between high coupling efficiency and ease of manufacture. The following examples illustrate this principle:
1. Bulk Optics
This is a popular technique in which lens arc used to focus the light from the semiconductor laser onto the endface facet of the fiber. It can provide high-coupling efficeincy if adequate lenses are used. The fact that multiple components, typically 1 or 2 lenses, are needed greatly increases the complexity of implementation and the reliability risk, however.
2. Hyperbolic Fiber Endfaces
The technique has provided coupling of 99% of the power from a single-mode laser into a single-mode fiber by using a high-power infrared laser to machine a hyperbolic surface on the fiber endface or tip. A hyperbola is the ideal shape for fiber coupling. Unfortunately, it is extremely difficult to accurately manufacture these fiber tips with sufficient yield that would warrant implementation in large-scale manufacturing of fiber-coupled single-mode laser modules.
3. Single-angle Wedge-shaped Fiber Endfaces
This has been used to couple 980 nanometer pump lasers to single-mode fibers. While it has the positive feature of being easy to manufacture, the achievable coupling efficiency has been limited to between 65 and 70%.
4. Double-angled Wedge-shaped Fiber Tips
This technique is a compromise between hyperbolic fiber endfaces and the single-angle wedge-shaped fiber endfaces described above. It provides higher coupling efficiency than single-angle wedge-shaped endfaces, but not as high as hyperbolic endfaces. It is significantly easier to manufacture and implement than hyperbolic endfaces, but not as easy as single-angle wedge-shaped fiber endfaces. To completely specify and manufacture the double-angled wedged-shaped fiber tip, four independent angles, having one of only two different values, and the location of three lines of intersection must be fabricated with sufficient precision.
SUMMARY OF THE INVENTION
The present invention is directed to an improved fiber endface shape and its manufacturing process. It achieves the coupling efficiency associated with the double-angled wedge-shaped fiber tips while maintaining the ease of manufacture associated with the single-angle wedge tips.
In general, according to one aspect, the invention relates to optical fibers, which include a core and surrounding cladding for transmitting electromagnetic radiation, and specifically the tips or endfaces that usually receive input radiation from a light source. The inventive tip comprises an end surface that is preferably substantially orthogonal to the axis, a first angled surface intersecting the end surface, and a second angled surface also intersecting the end surface.
In the preferred embodiment, break-lines between the angled surfaces and the end surface fall near an edge of a cladding-core interface and preferably outside that interface when the fiber and transmitted light are such that a substantial portion of the light is transmitted in the cladding.
In other embodiments, break-lines are substantially parallel to each other, with the first and second surfaces being opposed to each other on opposite sides of the fiber.
In still other embodiments, additional angled surfaces are added. In each case, the angled surfaces intersect the end surface at break-lines, preferably falling near the cladding-core interface.
In general, according to another aspect, the invention also relates to a method for manufacturing a tip for an optical fiber. This process comprises first cleaving an end surface in the fiber. At least first and second surfaces are then formed, angled relative to the end surface.
In the preferred embodiment, a spatial intensity profile of light exiting from the tip is detected, which is used to monitor the polishing of the first and/or second angled surfaces.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.
REFERENCES:
patent: 4490020 (1984-12-01), Sakaguchi et al.
patent: 4671609 (1987-06-01), Khoe et al.
patent: 4698084 (1987-10-01), Severijns et al.
patent: 4701011 (1987-10-01), Emkey et al.
patent: 4726641 (1988-02-01), Mori
patent: 4766705 (1988-08-01), Dholakia
patent: 4818263 (1989-04-01), Mitch
patent: 4839993 (1989-06-01), Masuko et al.
patent: 5011254 (1991-04-01), Edwards et al.
patent: 5037174 (1991-08-01), Thompson
patent: 5202948 (1993-04-01), Suhara et al.
patent: 5256851 (1993-10-01), Presby
patent: 5293438 (1994-03-01), Konno et al.
patent: 5413941 (1995-05-01), Koos et al.
patent: 5434940 (1995-07-01), Roff et al.
patent: 5455879 (1995-10-01), Modavis et al.
patent: 5526452 (1996-06-01), Dannoux et al.
patent: 5638471 (1997-06-01), Semo et al.
patent: 5812718 (1998-09-01), Carpenter et al.
patent: 0 086 155 (1983-08-01), None
patent: 54 01 9762 (1979-02-01), None
patent: WO 97/42533 (1997-11-01), None
Shah, Virenda S., et al., “Efficient Power Coupling from a 980-nm, Broad-Area Laser to a Single-Mode Fiber Using a Wedge-Shaped Fiber Endface,”Journal of Lightwave Tecnology IEEE, vol. 8, No. 9, 1990, pp. 1313-1318 (1990).
Conover Steven D.
Korn Jeffrey
Sharfin Wayne F.
Yang Thomas C.
Corning Lasertron, Inc.
Hamilton Brook Smith & Reynolds P.C.
Kim Ellen E.
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