JPH05206944A - Automatic adjustment device for optical modulation degree of electricity-light conversion device - Google Patents

Abstract

PURPOSE:To always output an optical signal with an optimum light modulation rate by providing a means detecting an input signal level and increasing/ decreasing the light modulation rate of a light modulation means in accordance with the increase/decrease of the input signal level. CONSTITUTION:A peak detector 4 inputting the output of an automatic gain controller AGC1 is provided. The output levels VL-VH of AGC1, in which the operation area of the light-emitting element of an electricity-light converter 2 becomes optimum, are stored. When the level range of an input signal becomes small and the output level of AGC1 becomes smaller than VL-VH, the detector 4 outputs an AGC control signal and increases the amplification factor of AGC1. When the output level of AGC1 becomes larger than VL-VH on the other hand, the detector 4 outputs the signal and reduces the amplification factor of AGC1. Thus, the operation range of the light-emitting element is adjusted and the optical signal can be outputted with the optimum light modulation rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic optical modulation degree adjusting device for an electro-optical conversion device, and more particularly, to an optical modulation degree which can be adjusted to an optimum value in accordance with an input signal level or the number of input signals. The present invention relates to an automatic light modulation degree adjusting device for an electro-optical converting device.

[0002]

2. Description of the Related Art Conventionally, as an optical modulation degree automatic adjusting device for an electro-optical converting device, an input signal is input to an amplifier 101 as an optical modulating means as shown in the block diagram of FIG. There is one that amplifies the signal level V1 to V2 in the range (optimum operation region) in which the optimum operation of the light emitting element can be obtained, inputs the signal level into the electro-optical converter 102, and outputs the light-modulated optical signal (Japanese Patent Laid-Open No. Hei 10-1999). 3-48536 gazette).

Incidentally, this conventional electro-optical conversion device includes:
Bias control circuit 1 for preventing the operating point of the light emitting element of the electro-optical converter 102 from becoming unstable due to temperature characteristics.
03 is provided.

In addition, the conventional electric device constructed as described above
For example, as shown in the block diagram of FIG. 4, the automatic optical modulation degree adjusting device of the optical converting device multiplexes input signals to a combiner 105 to combine them, and electrically combines the combined signals via an amplifier 101. The present invention can also be applied to an electro-optical conversion device for inputting into the optical converter 102.

[0005]

However, in the conventional automatic optical modulation degree adjusting device, since the amplification factor of the amplifier 101 as the optical modulation means is fixed, the input signal level or the multiplicity different from that is not provided. There is a problem that the optimum modulation degree cannot be obtained, the S / N characteristic is deteriorated, and erroneous conversion due to overmodulation occurs.

That is, when the multiplicity of the input signal becomes small, the input signal level becomes small, the effective operating region cannot be fully utilized, and the modulation becomes insufficient.
The deterioration of the / N characteristic deteriorates. In addition, when the multiplicity increases, the input signal level becomes large, exceeds the effective operation area, and overmodulates, and it becomes impossible to accurately convert the input signal into an optical signal.

It is an object of the present invention to provide an optical modulation degree automatic adjustment device for an electro-optical conversion device, which is capable of obtaining an optimum modulation degree according to the increase or decrease of the signal level or the multiplicity of an input signal. is there.

[0008]

A first automatic optical-to-optical conversion device for an electro-optical conversion device according to the present invention uses an electric signal for converting an input signal into an electric signal.
In an electro-optical conversion device for inputting to an optical converter, converting to an optical signal optically modulated by an optical modulator and outputting the optical signal, the optical modulation rate of the optical modulator is made variable and the input signal level is detected. A means for increasing / decreasing the light modulation rate of the light modulating means in response to the increase / decrease in the input signal level is provided. Adjustment device.

Further, the second automatic optical-to-optical conversion device for an electro-optical converting device of the present invention combines a plurality of input signals with a combiner, and then inputs them to the electric-to-optical converter. In an electro-optical conversion device which converts and outputs an optically modulated optical signal, the optical modulation rate of the optical modulation means is made variable, and the number of signals input to the combiner is counted to increase or decrease the number of input signals. Is provided with means for increasing or decreasing the light modulation rate of the light modulating means.

[0010]

In the first automatic optical-to-optical conversion device for an electro-optical conversion device of the present invention, the input signal level is detected and the optical modulation rate of the optical modulation means is increased or decreased in response to the increase or decrease of the input signal level. Since the means is provided, the optical modulation rate can be increased or decreased continuously or stepwise in response to the increase or decrease of the input signal level, whereby the optical signal is always output at the optimum optical modulation rate. be able to.

Further, in the second automatic optical-to-optical conversion device of the present invention, the optical modulation factor of the optical modulation means is made variable and the number of signals input to the combiner is counted. Since the means for increasing / decreasing the light modulation rate of the light modulating means is provided in response to the increase / decrease in the number of input signals, the light modulation rate of the light modulating means is increased / decreased in accordance with the increase / decrease in the number of input signals. Therefore, the optical signal can always be output at the optimum optical modulation rate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An automatic optical modulation degree adjusting device for an electro-optical converting device according to an embodiment of the present invention will be specifically described with reference to FIG.

In this electro-optical conversion device, an input signal is input to an electro-optical converter 2 via an amplification factor variable amplifier (hereinafter referred to as AGC) 1 as an optical modulator, and converted into an optical signal. It is configured to output. Further, this electro-optical conversion device includes a bias control circuit 3 that prevents the operating point of the light-emitting element of the electro-optical converter 2 from becoming unstable due to temperature characteristics.

Further, this electro-optical conversion device is an AGC
A peak detector 4 for inputting the output of (automatic gain control) 1 is provided. This peak detector 4 has an electric
The output level VL of the AGC 1 in which the operating region of the light emitting element of the optical converter 2 is, for example, the optimum operating region V1 to V2 shown in FIG.
˜VH is stored, and the input signal level of the output of AGC1 and the stored output level of AGC1 VL to VH are stored.
Are compared with each other, and an AGC control signal for instructing the increase or decrease of the amplification factor of AGC1 is generated so that the output signal level of AGC1 becomes VL to VH and is output to AGC1.

The AGC 1 inputs this AGC control signal to change the amplification factor continuously or stepwise,
It is constructed so as to output signals of the levels VL to VH.

In this electro-optical converter, when the level range of the input signal becomes small and the output level range of AGC1 becomes smaller than VL to VH, the peak detector 4 increases the output level range of AGC1. The AGC control signal is output to increase the amplification factor of the AGC 1 and the output level thereof is expanded to VL to VH.

Further, when the range of the level of the input signal becomes large and the range of the output level of AGC1 becomes larger than VL to VH, the peak detector 4 outputs an AGC control signal for decreasing the range of the output level of AGC1. , A
The amplification factor of GC1 is reduced and its output level is VL to V
Reduced to H.

Therefore, a signal having a level such that the operating region of the light emitting element is the optimum operating regions V1 to V2 is always input to the electro-optical converter 2, and the optical signal can be output at the optimum optical modulation rate. ..

In this embodiment, the optical modulation rate of AGC1 is changed based on the output of AGC1, but the optical modulation rate of AGC1 is changed based on the input of AGC1. Is also possible.

In an automatic optical modulation degree adjusting device for an electro-optical converting device according to another embodiment of the present invention, for example, as shown in FIG. 2, a large number of signal inputs (for example, signal input 1 to signal input 5). Are input to the combiner 5 to be combined, and the combined signal is passed through the AGC 1 serving as an optical modulator and the electro-optical converter 2
It is configured to be input to, converted into an optical signal and output. Further, this electro-optical conversion device includes a bias control circuit 3 that prevents the operating point of the light-emitting element of the electro-optical converter 2 from becoming unstable due to temperature characteristics.

Further, this electro-optical converting device counts the number of signal inputs inputted to the combiner 5, and the AGC1
The AG that changes the amplification factor of the signal corresponding to the increase or decrease in the number of input signals
An input signal counting circuit 6 for providing a C control signal to the AGC 1 is provided.

The input signal counting circuit 6 is configured to repeatedly count the number of signals input to the combiner 5 and output the counted number to the AGC 1 as an AGC control signal.

When the AGC control signal is input, the AGC 1 changes the amplification factor stepwise so that the output level of the AGC 1 is in the optimum operating range V1 to V2 corresponding to the count number.

In this electro-optical converter, the number of input signals is reduced and the output level range of AGC1 is VL to V.
When it is smaller than H, the AGC 1 increases the amplification factor in accordance with the number of decrease in the number of input signals, and expands the output level of the AGC 1 to the optimum operation region VL to VH.

When the number of input signals increases and the output level range of AGC1 becomes larger than VL to VH, AGC1 reduces the amplification factor corresponding to the increase in the number of input signals, and the output of AGC1. Level is the optimum operating area VL ~ V
Reduce to H. Therefore, a signal having a level such that the operating region of the light emitting element is the optimum operating region V1 to V2 is always input to the electro-optical converter 2, and the optical signal can be output at the optimum optical modulation rate.

[0026]

As described above, according to the first optical-modulation-degree automatic adjusting apparatus of the present invention, the input signal level is detected and the optical modulation is performed in response to the increase or decrease of the input signal level. Since the means for increasing or decreasing the light modulation rate of the means is provided, it is possible to increase or decrease the light modulation rate continuously or stepwise in response to the increase or decrease of the input signal level.
It is possible to always output the optical signal at the optimum optical modulation rate. As a result, it is possible to prevent the S / N characteristic from being deteriorated due to insufficient modulation, prevent erroneous conversion due to overmodulation, and improve the quality of the analog electric-optical transmission system.

Further, according to the first optical-to-optical conversion device of the present invention, the optical modulation degree automatic adjusting device makes the optical modulation rate of the optical modulation means variable and counts the number of signals input to the combiner. Since the means for increasing or decreasing the light modulation rate of the light modulating means is provided in response to the increase or decrease in the number of input signals, the light modulation rate of the light modulating means is increased or decreased stepwise in accordance with the increase or decrease in the number of input signals. Therefore, it is possible to always output the optical signal at the optimum optical modulation rate. As a result, it is possible to prevent the S / N characteristic from being deteriorated due to insufficient modulation, prevent erroneous conversion due to overmodulation, and improve the quality of the analog electric-optical transmission system.

[Brief description of drawings]

FIG. 1 is a block diagram of an electro-optical conversion device of the present invention.

FIG. 2 is a block diagram of another electro-optical conversion device of the present invention.

FIG. 3 is a block diagram of a conventional electro-optical conversion device.

FIG. 4 is a block diagram of another conventional electro-optical conversion device.

FIG. 5 is a V-P characteristic diagram of a light emitting device.

[Explanation of Codes] 1 AGC (amplifier) 2 Electric-optical injection converter 3 Bias control circuit 4 Peak detector 5 Combiner 6 Input signal number counting circuit

Claims (2)

[Claims] 1. An electric-optical conversion device for inputting an input signal into an electric-optical converter, converting the optical signal into an optical signal optically modulated by an optical modulator, and outputting the optical signal. The optical modulation rate of the optical modulator is variable. In addition, a means for detecting the input signal level and increasing / decreasing the optical modulation rate of the optical modulation means in response to the increase / decrease in the input signal level is provided. apparatus. 2. After combining a plurality of input signals with a combiner,
In an electric-optical conversion device which inputs to an electro-optical converter, converts the light signal optically converted by the optical modulation means and outputs the same, while changing the optical modulation rate of the optical modulation means,
A means for counting the number of signals input to the combiner and increasing or decreasing the light modulation rate of the light modulating means in response to the increase or decrease in the number of input signals is provided. Adjustment device.