JPH03244231A - Optical communication equipment - Google Patents

Abstract

PURPOSE:To eliminate the need for providing a light emitting element in a transmitter and to miniaturize the transmitter by providing a light source for optical signal separately from the transmitter, connecting a light transmission line for light source beam between the light source for optical signal and the transmitter, and providing a modulating means in the transmitter to optically modulate the optical signal from the above- mentioned light source. CONSTITUTION:The transmitter 16 inputs the light source beam with fixed power from a light source beam input terminal 15. An external modulator driving circuit 17 drives an external modulator 18 according to an electric signal inputted to an electric signal input terminal 2 and outputs the optical signal whose intensity is modulated from an optical signal output terminal 5 corresponding to the input electric signal. A receiver 6 inputs the optical signal transmitted by a light transmission line 11 for optical signal, from a light input terminal 7 and the optical signal is converted to the electric signal by a light receiving element 8, amplified by an amplifier reproducing circuit 9 and outputted from an electric signal output terminal 10. Therefore, without providing the light emitting element in the transmitter 16, the optical signal can be outputted while modulating the intensity according to the input electric signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical communication device that transmits information by optical modulation.

[Prior Art] Conventionally, there has been a device of this type as shown in FIG. This diagram is a simplified and rewritten version of the one published in December 1980, Telecommunications Technology News Co., Ltd., New Edition Optical Fiber Communication, page 20, supervised by Mitsuharu Maeda.
(1) is a transmitter, (2) is an electrical signal input terminal, (3) is a light emitting element modulation drive circuit provided in the transmitter (1), (4)
) is a light emitting element driven by the output of the drive circuit (3) provided in the transmitter (1), (5) is an optical signal output terminal, and (6)
is the receiver, (7) is the optical signal input terminal, and (8) is the receiver (
(6) is a light receiving element provided in the receiver (6), (9) is an amplification regeneration circuit that is provided in the receiver (6) and amplifies the output of the light receiving element (8), (10) is an electrical signal output terminal, (11) is an optical This is an optical transmission line for optical signals that connects the signal output terminal (5) and the optical signal input terminal (7).

Next, the operation will be explained.

The transmitter (1) has an electrical signal input terminal (2), a light emitting element modulation drive circuit (3), a light emitting element (4), and an optical signal output terminal (5).
), the electric signal inputted to the electric signal input terminal (2) is inputted manually, and the optical signal emitted from the light emitting element (4) is outputted from the optical signal output terminal (5).

The light emitting element modulation drive circuit (3) has an electrical signal input terminal (2)
The light emitting element (4) is modulated and driven by an electric signal inputted manually.

The light emitting element (4) converts a change in the electrical signal input to the electrical signal input terminal (2) into a change in light intensity, and emits a light intensity modulated optical signal.

The receiver (6) has an optical signal input terminal (7) and a light receiving element (8).
, an amplification and regeneration circuit (9), and an electric signal output terminal (10).The optical signal input to the optical signal input terminal (7) is used as human power, and the output of the amplification and regeneration circuit (9) is input to the electric signal output terminal (10). 10).

The light receiving element (8) converts changes in the light intensity of the optical signal inputted to the optical signal input terminal (7) into an electrical signal.

The amplification and regeneration circuit (9) amplifies the electric signal output from the light receiving element (8) and regenerates it into an electric signal equivalent to the electric signal input manually to the electric signal input terminal (2).

The optical signal transmission line (11) transmits the optical signal output from the optical signal output terminal (5) to the optical signal input terminal (7).

Therefore, an electric signal is manually applied to a transmitter equipped with a light emitting element, and the light emitting element is directly modulated and driven by the electric signal.

[Problem to be solved by the invention] Since the conventional optical communication device is configured as described above,
Transmitter that manually sends electrical signals (1) Individual light emitting elements (4)
In addition, the light emitting state of the light emitting element (4) provided in the transmitter (1) changes due to changes in the surrounding temperature,
The light emission power and light emission waveform fluctuate.

In addition, since the light emitting element (4) itself does not operate normally at extreme temperatures, the light emitting element (4) is equipped with an automatic adjustment circuit to compensate for temperature changes and a means to keep the temperature of the light emitting element itself constant. There was a problem that it was necessary to separately provide the transmitter (1) with the transmitter (1).

Purpose of the Invention This invention was made to solve the above-mentioned problems, and includes a light-emitting element in a transmitter, a circuit that compensates for the temperature characteristics of the light-emitting element attached thereto, and a circuit that maintains the temperature of the light-emitting element itself at a constant level. An object of the present invention is to provide an optical communication device that is configured without any means for this purpose, and in which a transmitter can be installed even in an environment where a light emitting element does not operate.

[Means for Solving the Problems] An optical communication device according to the present invention includes a light source for optical signals separately from a transmitter, an optical transmission line for light source light is connected between the light source for optical signals and the transmitter, The transmitter is equipped with a modulation means for optically modulating the optical signal from the light source.

[Operation] According to the above configuration, the light source for optical signals outputs light with a constant power, the optical transmission line for light source light transmits the output optical signal of the light source for optical signals to the transmitter, and the modulation signal provided in the transmitter is transmitted to the transmitter. The means is driven by the driving means, and transmits the light from the light source for the optical signal by an electrical signal.The modulated optical signal is transmitted to the receiver as the first output of the transmitter, so that the modulated optical signal is transmitted to the receiver as the first output of the transmitter. It is not necessary to include a light emitting element, and there is no need to provide a circuit for compensating the temperature characteristics of the light emitting element or a means for keeping the temperature of the light emitting element itself constant.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention, and the same parts as in FIG. 4 are denoted by the same reference numerals. (12) is an optical signal light source that outputs light source light with a constant power, (13) is an output terminal for this light source light, (14) is an optical transmission line for light source light,
(15) is a light source light input terminal into which the light source light is input through the optical transmission line (14), (16) is a transmitter, (17) is an external modulator drive circuit provided in the transmitter (16), (18) )
is also a drive circuit (17) provided in the transmitter (16).
is an external modulator driven by

The optical transmission line for light source light (14) connects the light source light output terminal (13) and the light source light input terminal (15), and connects the light source for optical signal (12).
transmits the output light of

Next, the operation will be explained.

The transmitter (16) inputs the light source light with a constant power from the light source light input terminal (15), and the external modulator drive circuit (17) drives the external modulator ( 18), an optical signal intensity-modulated according to the human-powered electric signal is sent to the optical signal output terminal (
Output from 5).

The receiver (6) inputs the optical signal transmitted through the optical signal transmission line (11) connected to the optical signal output terminal (5) through the optical input terminal (7), and receives the optical signal at the light receiving element (8). It is converted into an electrical signal, amplified by an amplification/reproduction circuit (9), and outputted from an electrical signal output terminal (1o).

Therefore, the transmitter (16) can output an optical signal whose intensity is modulated by the input electrical signal without being equipped with a light emitting element, and the transmitter (16) is equipped with a compensation circuit for the temperature characteristics of the light emitting element, and a light emitting element. This eliminates the need for a means to keep the temperature of the transmitter constant, and the transmitter can be made smaller.

FIG. 2 is an operational explanatory diagram showing input and output waveforms of the transmitter (16) of the above embodiment, in which (a) and e are electrical signal input terminals (2
), Figure (b) shows the signal waveform applied to the light source optical input terminal (
Figure 15) shows the optical waveform input manually, and Figure (c) shows the optical waveform output from the optical signal output terminal (5). As can be seen from this figure, light of constant power from the optical signal light source (12) is converted into an optical signal intensity-modulated by a human-powered electric signal and output.

Note that the above embodiments can be implemented regardless of whether the input electrical signal is an analog signal or a digital signal.

Furthermore, if the input electrical signal is a digital signal, an optical switch and its drive circuit are used instead of the external modulator (18) and the external modulator drive circuit (17), and the old GH level and Low level of the human-powered electrical signal are The light source light may be modulated by opening or closing the optical path connecting the light source light input terminal (15) and the optical signal output terminal (5) depending on the level.

Further, FIG. 3 shows another embodiment of the present invention.
The same parts as in the figures are given the same reference numerals.

(19a) and (19b) are shown in Example (7) above.
The transmitter/receiver is constructed by combining a receiver (16) and a receiver (6), and (20) is an optical splitter that branches the light source (12).

Each transceiver (19a), (19b) has an external modulator (
18a), (18b), drive circuit (17a),
(17b), and a light receiving element (8a).

(8b), an amplifier circuit (9a), and (9b).

The optical splitter (20) connects the light source light output from the optical signal light source (12) to a plurality of light source light transmission lines (14), (
14), and a plurality of transceivers (19a), (1
9b) external modulator (18a).

Input terminal (15a), (15b) for (18b)
) to transmit the source light.

Each modulator (18a), (18b) and light receiving element (8
a) and (8b) are input/output terminals (5a) and (7a), respectively.
), (5b), (7b)
1), read by (11).

Next, the operation will be explained.

The transmitter/receiver (19a) is connected to the drive circuit (
The external modulator (17a) is
8a) transmits the modulated light f; signal to the opposing transmitter/receiver (1
9b), the light receiving element (8b) converts the human-powered optical signal into an electrical signal, and outputs it from the amplifier (9b). Similarly, the optical signal transmitted by the transceiver (19b) is transmitted to the transceiver (19b).
9a) receives.

With this configuration, a plurality of transmitters and receivers can be configured with one light emitting element, which has the effect of reducing the number of light emitting elements in the entire system and downsizing the device.

[Effects of the Invention] As described above, according to the present invention, a light source for optical signals is provided separately from a transmitter, a transmission line for light source light is connected between the light source for optical signals and the transmitter, and light from the light source is provided. Since the transmitter is equipped with a modulation means for optically modulating the optical signal, the optical signal light source outputs light with a constant power, and the light source light transmission line transmits the output optical signal of the optical signal light source to the transmitter. , because the optical modulation means provided in the transmitter is driven by the driving means, optically modulates the light from the optical signal light source with an electric signal, and transmits this modulated optical signal to the receiver as the optical output of the transmitter. , it is not necessary to provide a light emitting element within the transmitter, and it is possible to obtain the effect that there is no need to provide a circuit for compensating the temperature characteristics of the light emitting element or a means for keeping the temperature of the light emitting element itself constant.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is an operation explanatory diagram showing the human output of the transmitter in the embodiment, where (a) the input signal waveform and (b) the diagram 1 shows the waveform of a light source from a manual light source, FIG. 1C shows the waveform of an output optical signal, FIG. 3 is a block diagram showing another embodiment, and FIG. 4 is a block diagram showing a conventional example. In the figure, (1) is a transmitter, (2), (2a),
(2b) is an electric signal input terminal, (3) is a light emitting element modulation drive circuit, (4) is a light emitting element, and (5). (5a), (5b) are optical signal output terminals, (6) is a receiver, (7), (7a), (7b) are optical signal input terminals,
(8), (8a), (13b) are light receiving elements, (
9), (9a), and (9b) are the panicle width regeneration circuits, (
10), (10a), (10b) are electrical signal output terminals, (11) is an optical transmission line for optical signals, (12) is a light source for optical signals, (13) is a light source light output terminal, and (14) is a light source. Optical optical transmission line, (15), (15a), (15b
) is the light source optical input terminal, (16) is the transmitter, ° (17),
(17a) and (17b) are external modulator drive circuits, ('1
g), (18a). (18b) is an external modulator, (19a), (19b)
is a transceiver, and (20) is an optical splitter. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A light source for optical signals whose output power is stably controlled; an optical transmission line for light source light connected to the light source for optical signals; and an optical transmission line connected to the optical transmission line for the light source; a transmitter comprising an optical modulating means for optically modulating an optical signal from the light source outputted through the transmitter, and a driving means for driving the modulating means; an optical transmission line for an optical signal connected to the modulating means; An optical communication device comprising: an optical receiver that receives a modulated optical signal from a modulating means connected to a signal optical transmission line.