JPS63100407A - Optical fiber coupler - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention and Prior Art) An optical fiber coupler typically supplies modulated light from a light emitting source to an optical fiber, and also supplies light from the optical fiber to a detection element. used.

Such couplers can also be used to multiplex or demultiplex modulated light that is or is to be propagated by an optical fiber. 1982
See co-pending application (application number 444.499) filed by the inventor on November 24, 2009.

Normally, a large number of couplers of this type are used, and it is desirable to be able to produce highly reliable couplers in large quantities at low cost with a minimum of production steps. Additionally, such couplers must function properly in environments with severe temperature changes and other influences that degrade the optical properties or alignment of the coupler and degrade the coupling function.

In order to keep losses low when coupling light between the end of the optical fiber and the emitter and detector, the positioning of the coupler element must be very precise. Injection molding techniques can be employed for this purpose, but the process is often complicated by the need for side pressure operations to fill all recesses in the coupler mold with material. Therefore, a coupler that avoids forming that requires side pressing operations is desirable.

Optical properties that allow focusing, beam splitting, or correction of spherical and coma aberrations to minimize splice losses in the coupler or to provide flexibility of use are also desirable.

SUMMARY OF THE INVENTION According to the teachings of the present invention, optical coupling is established between the ends of optical fibers and respective detectors and emitters through one or more focusing surfaces. A coupler is provided. By molding the coupler as a one-piece plastic part and configuring it so that the end of the optical fiber and the emitter and detector are precisely positioned in the pre-shaped cavity, high positional accuracy and, as a result, Accurate alignment can be obtained. The focusing surface that guides the light between the end of the fiber and the emitter and detector is also shaped as a recess in the coupler body. All critical components of the coupler body are formed in a single injection molding process, allowing the coupler to be manufactured accurately and reproducibly at low cost.

In a preferred embodiment of the invention, the focusing surface of the coupler is a reflective surface that operates on the principle of total internal reflection without a reflective coating. The surfaces may be aspheric or spherical depending on whether it is desired to correct spherical aberrations and coma or to provide flexibility in the placement of the focusing surfaces. The cost of the mold is approximately the same regardless of the shape. Side pressing can be avoided by locating all component receiving cavities on opposite sides of the coupler body. The focusing plane is split if complete separation of the optical path between the end of the optical fiber and the emitter and detector is desired. When using reflective surfaces, the coupler is not subject to changes in refractive index and dimensions due to temperature or other effects and changes in wavelength.

In another preferred embodiment, the coupler includes a groove extending to the beam splitting plane. The groove receives and positions the optical fiber such that the end of the optical fiber is proximate to the beam splitting plane. One optical path leads from the end of the optical fiber to the receiving cavity of the emitter or detector by reflection at the beam splitting plane. The other optical path leads via the beam splitting surface to the receiving cavity of the emitter or detector by total internal reflection from the shaped focusing surface. According to this embodiment, there is no need to press the side surface of the coupler mold.

In another embodiment of the invention, one focusing surface is a reflective surface and the other focusing surface is a refractive surface.

Embodiments The present invention defines an optical path in which at least two optical surfaces, reflective or refractive, are physically separated between an optical fiber end and an active element, such as an emitter or a detector. Regarding optical fiber couplers such as

The reflective or refractive surface of the coupler is typically formed as an interface between the air and the plastic material forming the coupler body.

According to a first embodiment of the invention shown in FIG.
The mounting has a boat 12 for securing the optical fibers and connectors for positioning at the interface 14 with the molded plastic. Coupler body 1o includes cavities 16 and 18 that are sized to preferably receive and precisely align one emitter or detector in normal use.

Emitters or detectors of the type utilized in the present invention include centered emission or detection trajectories. The optical path between the centers of voids 1416 and 18 and the end of the optical fiber at interface 14 is provided by ellipsoids 20 and 22, respectively. Those ellipsoids achieve total internal reflection and reflect N
In order to eliminate the need for a membrane, it is formed at an angle greater than the critical angle. Elliptical surfaces 2o and 22 are each empty 11m24
and 26 are molded inside the coupler body 10 as end faces. Such an aspheric surface eliminates spherical aberration. Ellipsoid 2
0, the shape is such that one focus of the ellipse is at the center point 28 in the air rf 416 where the light is emitted by the inserted light emitter or where the inserted detector responds to the light. defined differently. The other focal point of the ellipsoid 20 coincides with the position of the end of the optical fiber at the interface 14.

Optical path 30 is thus defined between the end of the optical fiber and center point 28. The ellipsoidal surface 22 is sized such that one focal point of the three-dimensional ellipse is located at a point 32 relative to the cavity 18 that has optical properties similar to those of the center point 28 relative to the cavity 16 . The other focal point of the three-dimensional ellipse of the ellipsoidal surface 22 is at the point where the optical fiber extends to the interface 14, so the optical path 3
4 is defined between point 32 and interface 14. Ellipsoid 20
and 22 when viewed from the location of interface 14, they generally appear as segments 36 and 38 in FIG. Varying the position of the innermost end 40 of the cavity 24 to vary the position of the dividing line 42 of the segments 36 and 38 and correspondingly adjust the percentage of light transmitted by the respective optical paths 30 and 34. be able to. In typical applications, this percentage is 50% for each optical path.
% each.

If it is desired to eliminate light propagation between points 28 and 32 to reduce the propagation of spurious light between them, cavities 24 and 26 may be mounted 90'' apart with respect to the axis of boat 12. You can also turn it to the desired position.

Elliptical surface 20 and/or ellipsoidal surface 22 may be segmented to eliminate crosstalk caused by reflections at interface 14 between light provided or received by cavities 16 and 18. The state of division when looking at the ellipsoidal surfaces 20 and 22 from the interface 14 is shown in FIG. When viewed from that position, the ellipsoid 22 occupies the left portion 46 and the right portion 48 of the field of view in FIG. do.

Usually, the material of the coupler body 10 is General El.
A clear, injection moldable plastic such as LEXAN® from the electric Company. In general, transparent acrylic or polycarbonate plastics have been found to be particularly useful.

Injection molding techniques for forming hollow interior surfaces within the coupler body 10 are well known in the prior art.

Several companies manufacture plastic lenses or other shaped optical molded parts that can be used in such couplers.

FIG. 2 shows another embodiment of a molded plastic coupler body 60. Coupler body 60 includes a mounting boat 62 that secures the optical fiber and connector such that the end of the optical fiber is centered at interface 64 . The respective optical paths 66 and 68 are connected to the interface 6 at the end of the optical fiber.
4 and the centers of cavities 70 and 72 that receive the emitters or detectors. The optical paths 66 and 68 are formed by total internal reflection ellipsoidal surfaces 74, 76 and 78. The ellipses of the total internal reflection elliptical surfaces 74 , 76 and 78 have a common focus at point 80 , and the other focus of the total internal reflection elliptical surface 74 is at the end of the optical fiber at the interface 64 . The other focus of the total internal reflection ellipse 76 is at point 82 in the cavity 70 and the other focus of the total internal reflection ellipse 78 is at a point 84 in the cavity 72. These points 82 and 84 are the locations where light is emitted or received by the emitters or detectors inserted into the respective cavities. Total internal reflection elliptical inner surface 76 is located midway between points 80 and 82, and total internal reflection elliptical internal surface 78 is located midway between points 80 and 84.

When molding the coupler body 60, all cavities are provided toward the top or bottom surface, so no lateral pressure work is required. This is a major advantage in terms of reduced costs and increased accuracy of injection molding of such couplers.

Point 8 which is the innermost end of the cavity forming the total reflection elliptical inner surface 76
The position of 6 is usually in accordance with the perspective view of FIG.
and 68. Although the reflective surface can be divided according to the pattern shown in FIG. 5, other patterns can also be adopted as desired.

Since each optical path 66,68 includes reflections from two opposing ellipsoidal surfaces, the focusing function of the reflective surfaces of each optical path can be corrected for comatic and spherical aberrations.

FIG. 3 shows a third practical example that utilizes an internal total internal reflection focusing surface in the optical path between the end of the optical fiber and the cavity that receives the emitter and detector. As shown, the coupler body 9
0 has a mounting boat 92 that secures the optical fiber to the coupler body 90 with its sheathed cable and connector intervening so that the end of the optical fiber is centered at the interface 94 with the plastic of the coupler body 90. . First and second cavities 96 and 98 are provided on opposite sides of the boat 92 for mounting within the coupler body 90 to accommodate emitters or detectors as desired. Leading edges 100 and 102 between cavities 96 and 98 are provided by total internal reflection collimating paraboloids 104 and Tj 106, end faces 105, and total internal reflection focusing paraboloids 108 and 110, respectively.

Since the internal total reflection focusing paraboloids 108 and 110 have focusing properties, there are no particular restrictions on their placement, and they can be placed at any distance from the interface 94 at the end of the optical fiber as desired. The division of the field of view provided by the total internal reflection collimator paraboloids 104 and 106 when viewed from the interface 94 can also be adjusted as described above with respect to FIGS. 4 and 5.

Forming the coupler body 90 also requires no lateral pressure work. Therefore, the coupler of the embodiment of FIG. 3 can be molded very efficiently. The couplers of FIGS. 1-3 are insensitive to changes in refractive index, size, and wavelength because all surfaces are reflective.

Figures 6(^) and 6(B) illustrate the use of a beam splitting surface to direct light between the end of an optical fiber and a cavity location that receives an emitter or detector. A second example is shown. FIG. 6(8) is a sectional view of the coupler body 120, and FIG. 6(B) shows the top surface 122. Coupler body 120 typically includes a filler 124 to which only the optical fiber is bonded such that the end of the optical fiber is adjacent a beam splitting surface 126 coated with a dielectric. Cavity 128 in FIG. 1 is centered immediately adjacent beam-splitting surface 126 and opens toward top surface 122 so that light can be emitted or received from the end of the optical fiber by reflection at beam-splitting surface 126. Position the emitter (or detector).

The portion of the light that is propagated through the beam splitting surface 126 due to the beam splitting function provided by the dielectric coating forms an optical path 130. This optical path 130 includes total internal reflection from a focusing surface 132 that redirects the optical path 130 towards the center of a cavity 134 holding the detector (or emitter) element.

The couplers of FIGS. 6(8) and 6(B) can be injection molded without applying any side pressure to the mold. The optical fiber end can be coupled to the beam splitting surface 126 through an index matching material, but such material need not be used. Figure 6 (A) and Figure 6 (B)
The embodiment achieves particularly efficient coupling from the emitter disposed inside the cavity 128 as well as to the cavity 134, which would normally be used to receive a detector.

Cavities 128 and 134 include recesses 136 for precise positioning of emitter or detector housings.

FIG. 7 shows a third embodiment of the invention. As shown, the coupler body 140 has a coupling 142 that receives the optical fiber 144 within the connector to position the end of the optical fiber 144 against an interface 146 with the coupler body 140. A first optical path 148 is from the end of the optical fiber 144 through a total internal reflection surface 150 to a detector or emitter assembly 152 inside the cavity 154 .
is formed up to. The second optical path 156 is connected to the optical fiber 14
4 through the refractive surface 158 to the coupler body 140.
to a light emitter or detector assembly 160 inside a second cavity 162 of.

As shown in FIG. 7, the detector and emitter are of a focusing type that utilizes a lens 164 to image or direct light from the semiconductor detector or emitter.

The present invention is not limited to this embodiment, and other forms of detectors and light emitters may be used as desired.

The total reflection inner surface 150 and the refraction surface 158 are connected to the optical fiber 144.
When viewed from the end, it has the characteristics described above with respect to FIGS. 4 and 5. Alternatively, the total internal reflection surface 150 and the refractive surface 158 may be divided as shown in FIG. Corresponds to the other side. Similarly, segment 114 in FIG.
and 176 indicate the totally reflective inner surface 150 and the refractive surface 158, or extensions of those surfaces as may be appropriate to form the indicated segment. Splitting the reflective and refractive surfaces in this manner is advantageous because it eliminates reflections from the interface 146 back into the opposing cavity, thus reducing crosstalk.

10(A) and 10(B) show a modification of the embodiment of FIG. 7. FIG. In this case, the reflective and refractive functions are provided by concentric surfaces 180 and 18 inside the coupler body 184.
It is divided between 2. FIG. 10(B) includes a reflective surface 182 and a refractive surface 180 that form reflective and refractive optical paths between an end 186 of the optical fiber and shoulders 188 and 190 that receive emitters or detectors, respectively. A portion of the coupler is shown. FIG. 10(^) is a view of these planes viewed from the end of the optical fiber.

The embodiment shown in FIGS. 10(A) and 10(B) also eliminates crosstalk between the emitter and detector elements due to reflections at the interface with the optical fiber.

In all of the embodiments described above, index matching materials may be used at the ends of the optical fibers to eliminate crosstalk.

The total internal reflection surface 150 in FIG. 7 and the reflective surface 182 in FIGS. 10(A) and 10(8) are each normally an elliptical surface as described above, and the two focal points are at the end of the optical fiber. and the optical center position of the cavity receiving the detector or emitter.

Refracting surfaces 158 and 180 are typically 0 artesian 0 void to eliminate spherical aberration as desired.
(Cartesian oval body).

The above utilizes one or more internal total internal reflection focusing surfaces with or without a refractive surface to center the end of an optical fiber with coupling to an emitter element or a detector element. A fiber optic coupler has been described that can be easily molded using injection molding techniques for precise alignment. The embodiments described above are merely examples of the invention, and the scope of the invention is limited only by the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a coupler according to the invention having an internal total reflection focusing surface, and FIG. 2 is a cross-sectional view of a coupler according to the present invention having an internal total reflection ellipsoid surface, manufactured by a mold that does not require lateral pressing operations. Fig. 3 is a cross-sectional view of a coupler different from Fig. 1, and Fig. 3 is a cross-sectional view of a coupler different from Fig. 1, which uses an internal total internal reflection paraboloid and is manufactured by a mold that does not require lateral pressing work. A cross-sectional view of the coupler; Figure 4 is a top view of the reflective surface in Figure 1, Figure 2, or Figure 3; Figure 5M is a view of the reflective surface in Figure 1, Figure 2, or Figure 3; The top views of another form of , Figure 6 (8) and Figure 6 (B), respectively,
FIG. 7 is a cross-sectional view and a plan view of a coupler according to a second preferred embodiment of the invention having a beam splitting surface and an internal total internal reflection focusing surface for achieving a combining function. FIG. 8 is a cross-sectional view of a coupler according to another embodiment of the present invention having a refractive focusing surface and an internal total internal reflection focusing surface. FIG. A top view of a focusing surface, FIG. 9 is a top view of another focusing surface for use with one or more couplers of the present invention, and FIGS. Figure (B) shows a top view and a cross-sectional view of another coupler according to the invention, respectively, having one refractive focusing surface and one internal total internal reflection focusing surface. 10.60.90,120,140,184...
・Coupler body, 12.62.92...Mounting boat, 1G, 18, 70, 72, 96, 98, 128,
134,154,162,188.190...
Cavity 20.22 ...Ellipsoid 30, 34.66, 68.100.102.130.1
48.156 ・・・・Optical path 74.76.78・
... Full anti-gA elliptical inner surface 104.106 ...
...Internal total reflection collimator paraboloid, 108.110
...Internal total reflection focusing paraboloid, 124...
...) bird, 142 ...coupling, 144 ...optical fiber, 150.182 ...total internal reflection, 158,
180...Refracting surface. FIG, 3 FIG, 4 FIG,
5FIG, 8
FIG, 9 Procedures Netl Official Book May 28, 1985 1, Case Description 1988 Patent Application No. 106160 2, Name of Invention Optical Fiber Coupler 3, Person Making Amendment Relationship to Case Name of Patent Applicant Name ADC Fiber Obtains Corporation 4, Agent address: 1-1-5 Minami Aoyama-chome, Minato-ku, Tokyo Date of amendment order (voluntary) 7. Contents of amendment (1) Page 16, line 19 of the specification of the present application Add the following text with a line break between and line 20. ``(Effects of the Invention) As described above, the present invention includes a coupler body made of a block body molded from a monolithic light-transmitting plastic material, and a pair of mutually opposing side surfaces of the coupler body. a recess for positioning and arranging a detector, a light emitter, and an optical fiber is formed integrally with the coupler body, and at least two optical surfaces are integrally formed inside the coupler body on the same side as the recess;
The coupler is characterized in that an optical path is formed inside the coupler body to achieve optical coupling between the end of the optical fiber and the respective detector and light emitter.
It is most suitable as a structure molded by injection molding technology, and in particular, a recessed portion for positioning and arranging a detector, a light emitter, and an optical fiber is formed integrally with the coupler body on a pair of mutually opposing side surfaces of the coupler body. Therefore, the molding die can be a simple mating die, which improves the molding accuracy and the dimensional accuracy of the molded product, and has the effect of making it possible to obtain a molded product with excellent quality. J or more

Claims (1)

[Claims] (1) Equipped with a coupler body made of a block molded from a monolithic light-transmitting plastic material, and a detector, a light emitter, and an optical fiber are positioned and arranged on a pair of opposing sides of the coupler body. a recess is formed integrally with the coupler body, at least two optical surfaces are integrally formed inside the coupler body on the same side as the recess, and at least two optical surfaces are formed integrally within the coupler body on the same side as the recess, and at least two optical surfaces are formed integrally with the end of the optical fiber and the respective detectors and light emitters. An optical fiber coupler characterized in that an optical path between which optical coupling is achieved is formed inside the coupler body.