FI82316B - Optical branching device - Google Patents

Abstract

The invention concerns an optical branching device for connection to a transmission link of optical fibre, which branching device comprises at least one flat glass substrate 1, 2 on which light channels 3, 5, 6, have been created by means of ion exchange technology, in which the diffraction coefficient of the light is greater than at other places on the glass substrate. The invention is characterized in that the branching device has two glass substrates 1, 2, each of which has a main light channel 3a, 3b going right across the glass substrate and a transmitter/receiver channel 5, 6 with essentially smaller cross-section area which branches into two symmetrical branches 5a, 5b, 6a, 6b which bend in opposite directions in order to be parallel to and unite with the main light channel 3a, 3b where the light channels 3, 5, 6, have essentially a semicircular cross-section, and the glass substrate is fixed together in such a way that the main light channels 3a, 3b are opposite each other and optically separated from each by a layer 7 with low diffraction coefficient lying between the glass substrate 1, 2. <IMAGE>

Description

! 82316

Optical splitter member

The invention relates to an optical branching member for connection to a transmission connection formed by an optical fiber, which branching member comprises at least one planar glass substrate in which light channels with a higher refractive index than elsewhere in the glass substrate are formed by ion exchange technology.

Today, there are many different local area network-10 network systems in which several smart devices connected to a common bus communicate with each other via the bus. Such bus solutions are generally implemented using commercially available electronic communication components and an electronic communication bus. However, electrical systems are not sufficiently reliable, for example in an industrial environment where there is a lot of electromagnetic interference. Optical fiber and optical communication is a viable alternative to copper conductor and electrical communication in applications where high reliability is required because optical fiber is immune to electromagnetic radiation and ground loops and provides complete electrical separation between devices. The fiber is also light and its high bandwidth can be utilized, for example, in real-time weather applications in an industrial environment.

It is an object of the present invention to provide an optical splitter member suitable for such optical bus structures.

This is achieved by an optical coupler member 30 of the type described in the introduction, which according to the invention is characterized in that the coupler member comprises two glass substrates, each having a main light channel extending across the glass substrate and a transmitter / receiver light channel having a substantially smaller cross-sectional area. - 2 82316 converge in opposite directions parallel to the main light channel and merge with the main light channel, the light channels comprising a substantially semicircular cross-section, and that the glass substrates are connected so that the main light channels are opposed and optically separated by a small gap between the glass substrates.

Opposite semicircular main light channels form a circular light channel having substantially the same diameter as the bus fiber that will be connected to both ends of this light channel so that the optical bus passes through the light channel. An optical transmitter component is connected to the side light channel on the second glass substrate and an optical receiver component is connected to the side light channel on the second glass substrate 15. In the branch element according to the invention, the optical signal can be connected from the optical transmitter via the side light channel to the bus simultaneously in both directions almost without loss (only with an ideal power-20 loss of 3 dB). Correspondingly, the desired optical power depending on the number of nodes connected to the bus can be switched from the bus to the optical receiver by means of a side light channel on the second glass substrate from the optical signal coming from either direction. The ratio of the cross-sectional area of the branch of the side light channel 25 to the cross-sectional area of the main light channel determines the amount of optical power captured from the bus. Since the side light channel connected to the transmitter component and the side light channel connected to the receiver component are on different substrates with a layer having a low refractive index 30 between them, the transmitter and the receiver are optically completely separated from each other. Therefore, the crosstalk between the transmitter and receiver of the same node on the bus is small. In this case, the node's own transmission does not interfere with the node's receiver. As a result, for example, the optical racing 35 bus can be implemented by detecting a message collision at a node, since the signal from the bus can only come from another node.

In addition, the light channel made by ion exchange technology has a low shape selectivity, which further reduces the attenuation of the optical signal connected to the bus. In addition, several different branches can be easily manufactured on the same substrate.

The invention will now be described in more detail by means of an exemplary embodiment with reference to the accompanying drawing, in which Fig. 1 shows a perspective view of two glass substrates of a branch member according to the invention when separated from each other; to which a fiber optic fiber and receiver and transmitter components are connected.

Figure 1 shows two rectangular, 20 planar glass substrates 1 and 2, on the second plane surface of which semicircular light channels 3a and 6 and 3b and 5, respectively, are formed by ion exchange techniques. When forming light channels, a suitable mask is formed on the surface of the glass substrate. dalla openings. A limited ion source is then formed on the glass substrate, preferably a silver film vaporized on the surface of the glass substrate, from which the ions penetrate the glass with the aid of an electric field and locally replace ions initially in the glass, such as Na * ions. When using a limited ion source, the dimensions of the light channels are determined by the width of the aperture in the mask and the thickness of the silver film: the narrower aperture in the mask provides a lower light channel.

Figure 3 illustrates light channels formed on the surface of the glass substrate 1. A substantially straight and wide main light channel 3a runs across the glass substrate 4 82316 from one edge to the other. The width of the main light channel 3a is preferably equal to the diameter of the optical bus fiber 10. From the second side edge of the glass substrate begins a side light channel 6 with a larger and substantially smaller cross-sectional area, divided into two symmetrical branches 6b and 6a which curve in opposite directions towards opposite ends of the main light channel 3a parallel to the main light channel. by its own cross-sectional area. This results in low shape selectivity for both the bus and the bus when connecting the optical signal. A narrower portion is thus formed in the main light channel 3a between the points where the branches 15a and 6b join the main light channel.

As stated above, the depths of the channels of semicircular cross-section are directly proportional to their width, so that the main channel 3a is considerably deeper than the side channel 6 or its branches 20a and 6b.

The second glass substrate 2 of the branch member respectively comprises a wide main light channel 3b extending across the glass substrate and a narrower side light channel 5 joining it. However, the side light channel 5 is displaced longitudinally with respect to the side light channel 6 on the glass substrate 1 so as not to be completely aligned.

According to Fig. 2, the glass substrates 1 and 2 are glued together with a low refractive index adhesive layer 7 between them, which is preferably e.g. silicone rubbers or a UV-curable adhesive. The glass substrates 1 and 2 are joined together so that the semicircular main light channels 3a and 3b face each other and form a light channel 3 having a substantially circular cross-section, the refractive index and diameter of which are preferably equal to that of the bus fiber 10 to be connected to the end of the channel 3. The low-refractive index adhesive layer between the glass substrates 1 and 2 optically separates the light channel halves 3a and 3b and thereby the transmitter and receiver branches 5 and 6 of the branch member.

Figure 3 illustrates how the bus fibers 10 are connected to the ends of the main light channel 3a. An optical transmitter component 8, such as an LED, is glued to the side surface of the branch member to transmit an optical signal to the transmitter channel 6. The best optical connection from the transmitter component to the transmitter channel 6 is achieved 9, 15 such as a PIN diode. Alternatively, the transmitter and / or receiver components may be connected to channels 5 and 6 by a separate optical fiber, commonly referred to as a tail fiber.

The figures and the related description are intended to illustrate the present invention only. In particular, the optical splitter member of the invention may vary within the scope of the appended claims.

Claims (6)

6,82316 An optical branching member for joining a transmission connection formed by an optical fiber, the branching member 5 comprising at least one planar glass substrate (1, 2) formed by ion exchange techniques with light channels (3, 5, 6) having a higher refractive index than elsewhere in the glass substrate, characterized in that that the branching member comprises two glass substrates (1, 2), each of which has a main light channel (3a, 3b) extending across the glass substrate and a transmitter / receiver light channel (5, 6) having a substantially smaller cross-sectional area, which is divided into two symmetrical branches (5a, 5b, 6a, 6b) curving in opposite directions parallel to the main light channel (3a, 3b) and merging with the main light channel, the light channels (3, 5, 6) comprising a substantially semicircular cross-section, and that the glass substrates are connected so that the main light channels (3a, 3b) are opposed and optically separated from each other by glass substrates (1, 2) 20 with an intermediate low refractive index layer (7). Branch member according to Claim 1, characterized in that the layer (7) with a low refractive index is made of silicone rubber. Branching element according to Claim 1 or 2, characterized in that the transmitter / receiver light channel (5) of the second glass substrate (2) is connected to the optical receiver component (9) and to the second optical transmitter component (8). Branch member according to Claim 3, characterized in that the receiver and / or transmitter components (8, 9) are connected directly to the side surface of the glass substrates (1, 2). A branch element according to claim 3, characterized in that the receiver and / or transmitter components are connected to the transmitter / receiver channels via an optical fiber. 7 82316 Branching element according to one of the preceding claims, characterized in that the transmitter / receiver channel (5, 6) joining the main light channel (3a, 3b) increases the cross-sectional area of the main light channel. 8 82316