JPS6132813A - Transmitter and receiver for optical signal - Google Patents

Abstract

PURPOSE:To obtain a node element for a simple optical repeater or data way having no light emission part by branching an optical signal incident from an optical fiber by an optical directional coupler, and receiving the optical signal by a photodetection part and leading it out as an electrical signal. CONSTITUTION:Luminous flux incident on an optical waveguide 21 is branched to optical waveguide terminals 23 and 24. An electrode 25 is provided to a parallel guide part and a voltage is impressed to vary the light quantity ratio of light beams branched to the optical waveguide terminals 23 and 24, and further a modulated electrical signal is inputted to the electrode 25 to modulate optical signals at the terminals of the optical waveguides 23 and 24. Now, when an optical coupling part is set to minimum coupling length, the light incident on the optical waveguide 21 from the fiber 16 while the electrode 25 is not biased travels to the terminal of the optical waveguide 24. At this time, a fiber 20 for transmission is arranged at the terminal of the optical waveguide 24 and a photodetecting element 18 is arranged at the terminal 23 across a fiber 30. Part of the optical signal from the optical fiber 16 is received by the photodetecting element 18 by impressing a voltage to the electrode 25 partially.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to the node function of an optical dataway in optical fiber communication, and the function of extracting a part of the signal transmitted to the optical fiber and further transmitting a new signal. related to providing.

Conventional Structure and Problems Therein FIG. 1 shows an optical 71-wire repeater and node elements of a dataway. Figure 1 e) shows the repeater configuration. An optical signal entering from an optical fiber 1 is converted into an electrical signal by a light receiving element 3, and then signal processing is performed by an electrical signal processing device 4, which reproduces the signal or adds a new signal. The light is transmitted to the external optical fiber 6 by driving a light emitting element 6 such as a light emitting diode or a semiconductor laser.

FIG. 1('b) shows a node configuration of an optical fiber dataway. The optical signal entering from the optical fiber 8 is switched or branched by an optical branching means 9 such as an optical switch or branching/branching, and during normal operation, the light receiving element 1
0 is converted into an electrical signal, and further electrical signal processing such as reproducing the signal and adding a new signal is performed in the processing section 11.
The light is transmitted to the optical transmission line by driving the light emitting element 12, and is transmitted to the optical fiber 14 through the coupling section 13, which is composed of an optical switch, a branching coupler, and the like. On the other hand, when there is an abnormality in the light receiving section 10.degree.

In this way, an optical repeater or dataway node has a light receiving section,
It has a complex configuration, consisting of an electrical signal processing section and a light emitting section.

OBJECTS OF THE INVENTION Accordingly, the present invention provides a simple optical repeater or dataway node element that does not have a light emitting section.

Composition of the invention A forward sending and receiving device according to the present invention is shown in FIG.

The device of the present invention includes an optical directional coupler 17 having optical switch, branching, and modulation functions, a light receiving section 18, and an electrical signal processing section 1.
Consists of 9. The optical signal entering the optical fiber is branched by the optical directional coupler 17, received by the light receiving section 18, and taken out as an electric signal to the outside. Further, the transmission signal is sent to the fiber 2o by modulating the input light beam from the optical fiber 16 with a coupler 17 serving as a modulator.

DESCRIPTION OF EMBODIMENTS The case where 17 in FIG. 2 is an optical directional coupler will be explained. FIG. 3 shows an example of an optical directional coupler.

It is composed of two waveguides placed close to each other on the base 26, and the light beam incident on the optical waveguide 21 is transmitted to the optical waveguide ends 23 and 24.
It is branched into. By providing an electrode 26 on the 1000-row waveguide portion and applying a voltage, it is possible to change the ratio of the amounts of light branched to the ends of the optical waveguides 23 and 24. Further, when a modulated electrical signal is input to the electrode 25, the optical signal at the ends of the optical waveguides 23 and 24 is modulated. Now, when the optical coupling section is set to the minimum coupling length, the light incident on the waveguide 21 from the fiber 16 will migrate to the end of the waveguide 24 when the electrode 26 is in a non-biased state.

At this time, the sending fiber 2o is placed at the 24th end, and the light receiving element 31 is placed at the 23rd end via the fiber 30.

The relationship between the optical output at the ends of the waveguides 23 and 24 and the voltage applied to the electrode 25 at this time is shown in FIG. The output at the end of waveguide 23 is shown by curve 30A, and the output at the end of waveguide 23 is
The output at the four ends is shown by curve 2OA. Furthermore, when a modulation voltage of 19 mm is added to the processing unit 19 having a modulation function centered on the voO applied voltage, outputs of 20 mm and 3
0m is modulated and output as shown by curve 40. In this way, when arranged as a transmission system via an optical fiber, the optical signal from the optical fiber 16 inputted from the end of the waveguide 21 is partially transmitted to the light receiving element by applying a voltage to the electrode 26. It becomes possible to receive it at 18. Furthermore, the optical signal sent to the other end is sent from the processing section 19 serving as a signal generator to the electrode 2.
By inputting an electric signal to 6, the signal is sent out from the waveguide 24 end.

Since this modulation is also modulated into the light to the end of the waveguide 23, it is necessary to identify the signal at the receiving end. Transmitting and receiving devices with such a configuration not only do not require a light emitting element, but also can increase the amount of light on the main transmission path by changing the applied voltage when there is no received signal, and furthermore, can prevent failures in the electrical signal system. There are nine cases where the main transmission line is not disturbed even when there is no voltage. Therefore, it can be used as a simple dataway node element. For such an element, it is necessary not only to use it with a minimum bond length, but also to select an appropriate bond length depending on the application. For example, by doubling the coupling length, it is also possible to invert the output end and use it. Further, similar functions can be configured not only in the directional coupler but also in other waveguide type switches.

Note that it is also possible to use the fibers 16, 20, 30 as waveguides and integrate them together with the light receiving element 18 on the substrate.

Effects of the Invention (1) It is possible to configure a relay or dataway node that does not require a light source.

(2) A fail-safe configuration can be achieved with the dataway node configuration.

(3) Furthermore, depending on the position of the node, it is possible to adjust the light amount ratio between the main optical path and the receiving end.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are block diagrams of the basic configuration of a repeater or dataway node, Figure 2 is a block diagram of the basic configuration of the present invention, and Figure 3 is an optical directional coupler of the present invention. FIG. 4 is a diagram showing applied voltage-light output characteristics of the directional coupler. 16.20.30...Optical phino <, -1-r
...) directional coupler, 18... light receiving section. Name of agent: Patent attorney Toshio Nakao and 1 other person @2
Zuku I Tada de Taste

Claims (2)

[Claims] (1) A means for modulating a light beam incident from an optical fiber, a means for branching this incident light, and a light receiving means for converting the branched light into an electrical signal,
1. An optical signal transmitting/receiving device characterized by having means for guiding the signal to two optical fibers. (2) An optical signal according to claim 1, characterized in that the means for modulating the light beam incident from the optical fiber and the means for branching the incident light are performed by the same optical branching type modulator. Transmitting/receiving device.