DD246177A1

DD246177A1 - OPTICAL STAR COUPLER

Info

Publication number: DD246177A1
Application number: DD28722786A
Authority: DD
Inventors: Rolf Goering; Gerd Schreiter
Original assignee: Univ Schiller Jena
Priority date: 1986-02-21
Filing date: 1986-02-21
Publication date: 1987-05-27

Abstract

Die Erfindung betrifft einen optischen Sternkoppler fuer Lichtwellenleiter mit optisch transparentem Mischerbereich. Derartige Bauelemente werden in optischen Signaluebertragungssystemen eingesetzt. Der erfindungsgemaesse Koppler ist besonders fuer den Einsatz in Datenbussystemen geeignet. Ziel der Erfindung ist ein geringer Material- und Kostenaufwand. Geringe Leistungsverluste werden angestrebt. Diese Aufgabe wird durch einen Sternkoppler fuer Mehrmoden-Lichtwellenleiter unter Verwendung eines zylindrischen optisch transparenten Mischerstabes erfindungsgemaess dadurch geloest, dass der Mischerstab in einem rotationssymmetrischen Teil zentrisch gelagert ist und an seinen beiden Enden sich rotationssymmetrische Fassungsteile anschliessen, deren eine Endflaeche mit einer Endflaeche des Mischerstabes in einer Ebene liegt und die jeweils eine zentrische Kegelbohrung aufweisen, deren kleinerer Durchmesser zum Mischerstab zeigt und in denen die Lichtleiterkerne derart zusammengefuehrt sind, dass sich ihre Enden in der Ebene sowohl gegenseitig seitlich beruehren als auch mit ihren Endflaechen gemeinsam an der Endflaeche des Mischerstabes anliegen.The invention relates to an optical star coupler for optical fibers with optically transparent mixer area. Such devices are used in optical signal transmission systems. The coupler according to the invention is particularly suitable for use in data bus systems. The aim of the invention is a low material and cost. Low power losses are sought. This object is achieved by a star coupler for multimode optical waveguide using a cylindrical optically transparent mixer rod erfindaess characterized in that the mixer rod is mounted centrally in a rotationally symmetric part and connect at its two ends rotationally symmetrical socket parts whose one end face with an end surface of the mixer rod in a plane is located and each having a central tapered bore whose smaller diameter to the mixer rod shows and in which the fiber optic cores are combined such that their ends in the plane both mutually laterally touch as well as with their Endflaechen abut the end surface of the mixer rod.

Description

Buchse mit Innengewinde das Lichtwellenleiterbündel zum Mischerstab automatisch justiert ist. Diese Anordnung ist einfach, kompakt und läßt sich in einfacher Weise montieren. Durch die dichte Flächenpackung der Lichtwellenleiter im Bereich der Stirnflächen werden die optischen Verluste minimal gehalten.Bushing with internal thread, the fiber optic bundle is automatically adjusted to the mixer rod. This arrangement is simple, compact and can be mounted in a simple manner. The dense surface packing of the optical waveguides in the area of the end faces minimizes the optical losses.

embodiment

Das Wesen der Erfindung soll an einem in der Zeichnung im Längsschnitt dargestellten Ausführungsbeispiel eines erfindungsgemäßen Sternkopplers näher erläutert werden. Ein Bündel von Lichtwellenleitern 8, welches vorzugsweise aus Mehrmoden-Lichtwellenleitern mit einem optischen Mantel aus Kunststoff besteht, wird mit dem Schutzmantel in einer Hülse 1 eingekittet. Als Klebemittel 7 kann hierbei Epoxidharzklebstoff verwendet werden. Die vom Schutzmantel befreiten Lichtwellenleiterenden laufen in einer Fassungshülse 2 zusammen, die in die Hülse 1 eingeschraubt ist. Auf Hülse 2 ist ein Fassungsteil 3 aufgeschraubt, welches eine konische Innenbohrung besitzt. In dieser Bohrung werden die Lichtwellenleiterkerne in Richtung zu den Stirnflächen hin so zusammengeführt, daß sie sich genau an den Stirnflächen seitlich berühren. An der planaren Stirnfläche des Fassungsteiles 3 liegt somit in der Kegelbohrung ein Faserbündel in dichter Flächenpackung vor. Der Kegelwinkel wird möglichst klein gehalten (=2°). Das Fassungsteil 3 besitzt ein Außengewinde, zu dem die Kegelbohrung exakt zentrisch verläuft und auf dem eine Verbindungshülse 4 aufgeschraubt ist. Der Mischerstab 9, welcher vorzugsweise aus Quarzglas besteht, ist zentrisch in den Teilen 5 und 6 gelagert. Die Schraubkombination von 5 und 6 gestattet es dabei, die Länge der mechanischen Fassung auf die Mischerstablänge exakt einzustellen. Das Teil 5 besitzt das gleiche Außengewinde wie das Teil 3 und wird in die Verbindungshülse 4 eingeschraubt, bis'sich die Stirnflächen von Teil 3 und 5 bzw. 6 berühren und somit das Faserbündel auf den Mischstab stößt. Zur besseren mechanischen Fixierung sowie zur Gewährleistung einer verlustarmen optischen Verbindung wird der Stoßbereich mit einem Optikklebstoff verkittet, der höchstens die Brechzahl des optischen Mantels haben darf, da ein Teil dieses Klebstoffes in den konischen Bündelbereich hineinläuft. Die Figur zeigt einen Durchgangskoppler mit entsprechend zwei Lichtwellenleiterbündeln. Bei einem Reflexionssternkoppler würde ein Bündel entfernt und die entsprechende Stirnseite des Mischerstabes mit einer Spiegelschicht (aus Al, Ag oder Cu) bedeckt.The essence of the invention will be explained in more detail on an embodiment shown in the drawing in longitudinal section of a star coupler according to the invention. A bundle of optical waveguides 8, which preferably consists of multimode optical waveguides with an optical sheath made of plastic, is cemented to the protective sheath in a sleeve 1. As the adhesive 7, epoxy resin adhesive may be used. The freed from the protective sheath fiber ends come together in a socket sleeve 2, which is screwed into the sleeve 1. On sleeve 2, a socket part 3 is screwed, which has a conical inner bore. In this hole, the optical waveguide cores are brought together in the direction of the end faces so that they touch each other laterally exactly at the end faces. At the planar end face of the socket part 3 is thus in the conical bore a fiber bundle in dense surface packing before. The cone angle is kept as small as possible (= 2 °). The socket part 3 has an external thread to which the conical bore runs exactly centric and on which a connecting sleeve 4 is screwed. The mixer rod 9, which preferably consists of quartz glass, is mounted centrally in the parts 5 and 6. The screw combination of 5 and 6 makes it possible to precisely adjust the length of the mechanical socket to the mixer rod length. The part 5 has the same external thread as the part 3 and is screwed into the connection sleeve 4 until the end faces of part 3 and 5 or 6 touch and thus the fiber bundle strikes the mixing rod. For better mechanical fixation and to ensure a low-loss optical connection of the joint area is cemented with an optical adhesive, which may have at most the refractive index of the optical cladding, since a part of this adhesive runs into the conical bundle area. The figure shows a passage coupler with two optical fiber bundles. In a reflection star coupler, a bundle would be removed and the corresponding end face of the mixer rod covered with a mirror layer (made of Al, Ag or Cu).

Claims

Invention claim:

1. Optical star coupler for multimode optical fiber using a cylindrical optically transparent mixer rod, characterized in that the mixer rod is mounted centrally in a rotationally symmetric part and connect at its two ends rotationally symmetrical socket parts, one end face of which lies with an end face of the mixer rod in a plane and each having a central tapered bore whose small diameter is to the mixing rod and in which the optical waveguide cores are merged so that their ends in the plane both mutually laterally and abut with their end faces together on the end face of the mixer rod.

For this 1 page drawing

Field of application of the invention

The invention relates to an optical star coupler for optical waveguides on the basis of an optically transparent mixer region. Such a star coupler can be used in optical signal transmission systems with multimode step index fibers, in particular in conjunction with fibers whose optical sheath consists of plastic. It is thus particularly suitable in optical data bus systems in which all participants are connected to a common point (star point). Such star network data bus systems are used in automation and computing technology as well as in optical waveguide measurement technology.

Characteristic of the known technical solutions

Optical star couplers for optical fibers with a mixer region are known. In Applied Optics 13 (1974), p. 2540, the mixer section consists of a cylindrical glass rod, on the end faces of which the fiber bundles abut, wherein the optical waveguides consist up to the end face of core and jacket. Such an arrangement has high insertion losses. In order to reduce the insertion loss different solutions have been proposed, the conductors merge laterally into a bundle in different ways, and simultaneously produce a tapered taper towards the mixer area, the mixer area itself is partially realized by the laterally fused fibers (DE-OS 2731377, DE-OS 2812346, DE-OS 2837682, DE-OS 2942318). However, these solutions require an increased effort not only for the preparation of the necessary Schmelzflußverbindungen, but also for fixing, holding and encapsulation of the entire structure. An easily mountable and fixable optical star coupler with a cylindrical mixer region is proposed in JP 59-135417. However, the unilaterally expanded glass capillaries used there for B.ündeljustierung do not have the required centricity of the inner opening, so that an additional adjustment of the two fiber bundles to the mixer rod is necessary. In DD 210358, the mixer consists of an optical adhesive within a capillary, which is widened on both sides and at the same time serves for fiber bundling. Although simple bundle alignment is ensured in this case, the optical losses are very high for fibers with relatively thick optical sheath. In addition, the optical adhesives have the disadvantage that they tear at temperature reduction at the necessary adhesive thicknesses, which also leads to large losses and thus to significant limitations of the applicability of such star couplers in practice.

Object of the invention

The aim of the invention is an optical star coupler that can be produced with low material and cost, but at the same time has the necessary performance and reliability for a practical application.

Explanation of the essence of the invention

The invention has for its object to provide an optical star coupler, which guarantees low losses of optical power and is easy to manufacture. It is intended to be suitable for multimode optical waveguides which have an optical plastic jacket.

The solution of this object is achieved by an optical star coupler for multimode optical fiber using a cylindrical optically transparent mixer rod according to the invention characterized in that the mixer rod is mounted centrally in a rotationally symmetric part and connect at its two ends rotationally symmetrical socket parts whose one end face with an end face of Mixer rod is in a plane and each having a central tapered bore, whose smaller diameter to the mixer rod and in which the optical waveguide cores are merged so that their ends in the plane both mutually touch laterally and abut with their end faces together on the end face of the mixer rod , The fiber ends freed from the optical jacket are thus bundled by a first mounting part in such a way that they converge slightly conically towards the mixer rod (cone angle = 2 °) and touch laterally in the area of the end faces. The conical guide bore should run centric to the external thread of the socket part. The mixer rod is also held in a second socket part centric to an external thread. The external threads of the first and second mounting part are identical, so that by screwing together in a corresponding