DE2841133A1 - Tapping element for optical fibre - follows curved section to receive light emerging from side without breaking into it - Google Patents

Abstract

A tapping element branches off a light component from an optical fibre without breaking into it. A section of the fibre is so markedly curved that light emerges from one side of it. A second optical fibre runs in parallel along this curved section. the second fibre has a higher numerical aperture than the first. The second fibre can be planar with a side border forming a curved groove on a support. This grooves receives the first fibre. The radius of curvature of the latter can increase in the direction of the light propagation. The width of the second fibre can increase in the same direction along the curvature.

Description

Branch element

The present invention relates to a branch element for Branching off a portion of light from an optical waveguide.

For optical communication systems, especially for data bus systems, are Branch structures are required that allow certain, mostly low, light energies to be coupled out from a through-line, e.g., a single optical fiber.

So far only branch elements are known that are in the through line must be inserted so that the optical waveguide, which acts as a through line serves, must be interrupted.

The object of the present invention is to provide a branch element of the Specify initially mentioned type in which the optical waveguide is not interrupted must become.

The object is achieved in that the waveguide along a Piece is so strongly curved that laterally light emerges from it and that lengthways of the curved piece a second optical waveguide running parallel to it which has a larger numerical aperture than the optical waveguide.

Preferably the optical waveguide is with an optical fiber educated. It preferably consists of a glass fiber, in particular a core-sheath glass fiber.

A preferred embodiment is designed so that the second optical waveguide formed with a planar waveguide. is.

A particularly expedient embodiment is then designed in such a way that that the planar waveguide has a side boundary of a curved groove on one Forms carrier in which the optical waveguide is inserted.

The radius of curvature of the optical waveguide advantageously decreases seen in the direction of propagation of light, along the length of the piece of a small one Value starting to. This can prevent the second waveguide overcoupled light is fed back into the waveguide.

Such feedback can also be advantageously prevented by that is the width of the second optical waveguide along the length in the direction of propagation of light increases.

The basis of the proposed branch element is the utilization the effect that light radiates radially from sufficiently curved waveguides.

An exemplary embodiment of the invention is shown in the figure and is described in more detail below.

The figure shows the basic structure of the exemplary embodiment in plan view.

In a photo-lithographically produced groove, the width of which is identical with the diameter of the optical fiber 1 to be inserted and which has a radius of curvature R, the optical fiber 1 is inserted. The outer edge of the groove is designed as a planar waveguide 2 and has the task of the curved Fiber 1 radially emitted light to a branching fiber 3, which is also a Core-sheath glass fiber can be carried on. In order for the emitted light as To act waveguide, the numerical aperture of the planar waveguide 2 higher than that of the optical fiber. To increase the efficiency of the branch can be the point of contact between the round optical fiber 1 and the rectangular one planar waveguide 2 be filled with an immersion liquid, whose refractive index is the same as that of the cladding of the optical fiber.

The insertion losses of the proposed branch amount to of the order of magnitude of 0.2 dB and are independent of the jacket thickness of the used Core-sheath fiberglass.

The branch can be accessed at any convenient location Job inserted and removed again without the fiber 1 being processed in any way must become.

With a given fiber, the branched off light energy can be controlled by suitable Selection of the radius of curvature R and the angle of curvature t, i.e. the curved piece S, can be specified. Both the curvature radius and the curvature angle can be determined with the help of the photolithographic Thick film technology can be defined very precisely. The planar waveguide can manufacture in the same work step.

In order to couple back from the waveguide 2 into the waveguide 1 to avoid, it is useful if the radius of curvature R is in the direction of propagation over the angle r.Q, i.e. along the piece S, increases. Instead of that or in addition Feedback can also be prevented by increasing the width of the waveguide 2 is not constant, but also in the direction of propagation of the light the angle ~ increases.

8 claims 1 figure

Claims (8)

Claims branch element for branching off a portion of light an optical waveguide, d u r c h e k e n n n e i c h n e t that the Waveguide along a piece (S) is so strongly curved that light from the side emerges from it, and that along the curved piece a parallel second optical waveguide (2) is present, which has a larger numerical aperture than the optical waveguide. 2. Junction element according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the optical waveguide is formed with an optical fiber. 3. Junction element according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the optical fiber consists of a glass fiber. 4. Junction element according to claim 3, d a d u r c h g e k e n n z e i c h n e t that the glass fiber consists of a core-sheath glass fiber. 5. Junction element according to one of claims 1 to 4, d a d u r c h it is noted that the second optical waveguide (2) with a planar waveguide is formed. 6. Junction element according to claim 5, d a d u r c h g e k e n n z e i c h n e t that the planar waveguide is a side boundary of a curved one Forms groove on a carrier in which the optical waveguide is inserted. 7. Junction element according to one of the preceding claims, d a d u Note that the radius of curvature of the optical waveguide seen in the direction of propagation of the light, increases along the piece (S). 8. Junction element according to one of the preceding claims, d a d u r c h g e k e n n z e i c h -n e t that the width of the second optical waveguide seen in the direction of propagation of the light, increases along the piece (S).