JPH0723006A - Electro-optical converter - Google Patents

Abstract

PURPOSE:To provide the electro-optical converter by which a reverse bias is not applied to an electro-optical converting element, even if a frequency multiple signal is inputted in a state that a power source is not turned on to a device. CONSTITUTION:In the electro-optical converter for converting a frequency multiple signal to which a reference frequency signal is multiplexed, this converter is provided with a switch 2 for deriving selectively the frequency multiple signal, a filter 4 for extracting a pilot signal from the frequency multiple signal, a detector 6 for DC-detecting the pilot signal extracted by this filter 4, a comparator 7 which is actuated by turning on a power source, comparing a detected output of the detector 6 and a reference voltage, and setting the switch 2 to an ON-state only at the time when the detected output exceeds the reference voltage, and a laser diode 3 for converting the frequency multiple signal derived by the switch 2 to an optical signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical / optical converter for converting, for example, frequency-multiplexed RF signals into optical signals.

[0002]

2. Description of the Related Art Electricity used in conventional optical transmitters, etc.
As shown in FIG. 2, the optical conversion device directly supplies the frequency multiplex signal supplied to the input terminal 1 to the laser diode 3 and modulates the laser diode 3 with the frequency multiplex signal so that the laser diode 3 To obtain an optical signal corresponding to the frequency-multiplexed signal.

However, the conventional electricity /
In the optical conversion device, if the frequency-multiplexed signal is input when the device is not powered and the laser diode is not biased, the signal causes the laser diode to be reverse-biased. was there.

[0004]

As described above, the conventional electro-optical conversion device has an electro-optical conversion element which operates when a frequency-multiplexed signal is input while the device is not powered on. There is a problem that reverse bias is applied.

The present invention has been made to solve the above-mentioned problems, and even if a frequency-multiplexed signal is input in a state where the power is not turned on to the device, the electric / optical conversion element is not reverse-biased. An object is to provide a light conversion device.

[0006]

In order to achieve the above-mentioned object, an electrical / optical conversion device according to the present invention is an electrical / optical conversion device for converting a frequency multiplexed signal in which a reference frequency signal is multiplexed into an optical signal.
In the optical conversion device, a switch for selectively deriving a frequency-multiplexed signal, a filter for extracting a reference frequency signal from the frequency-multiplexed signal, a detector for direct-current detecting the reference frequency signal extracted by this filter, and a power-on When the detector is started, it compares the detection output of the detector with the reference voltage, and sets the switch to the ON state only when the detection output is higher than the reference voltage, and the frequency-multiplexed signal derived by the switch is converted into an optical signal. An electric / optical conversion element for conversion is provided.

Further, the reference frequency signal is a pilot signal of a specific frequency.

[0008]

In the electric / optical conversion device having the above structure, the reference frequency signal such as the pilot signal is taken out from the frequency multiplexed signal, and the electric / optical conversion is performed according to the comparison result of the DC voltage component of the reference frequency signal and the reference voltage. By deriving the frequency-multiplexed signal input to the element, the comparison processing is not executed when the power is not supplied to the device, and the frequency-multiplexed signal is not supplied to the electrical / optical conversion element.
Reverse bias is not applied to the light conversion element.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of an optical transmitter according to the present invention. In FIG. 1, reference numeral 1 is an input terminal 1 to which a frequency multiplexed signal is supplied. The frequency-multiplexed signal supplied to the input terminal 1 is branched into two, one is supplied to the laser diode 3 via the switch 2, and the other is supplied to the bandpass filter 4.

The bandpass filter 4 extracts a pilot signal of a specific frequency from the frequency multiplexed signal. The extracted pilot signal is amplified by the amplifier 5 and then supplied to the detector 6. The wave detector 6 is composed of, for example, a rectifier circuit and detects the DC voltage of the input pilot signal. The detected voltage is sent to the comparator 7 together with the reference voltage.

The comparator 7 compares the detected voltage with the reference voltage, and turns on / off the switch 2 based on the comparison result.
Off control is performed. Specifically, when the detected voltage is lower than the reference voltage, the switch 2 is set to the off state,
When the detected voltage is equal to or higher than the reference voltage, the switch 2 is turned on.

That is, in the optical transmitter having the above-mentioned structure, the fact that the pilot signal of the specific frequency is inserted into the signal at the time of the optical transmission of the frequency multiplexed signal is utilized,
When the frequency-multiplexed signal is input, the bandpass filter 4 extracts a pilot signal, the amplifier 5 amplifies the pilot signal, and the detector 6 detects it. And
The voltage detected by this detection is compared with the reference voltage by the comparator 7, the switch 2 is set to the ON state only when the detected voltage becomes equal to or higher than the reference voltage, and the input frequency multiplexed signal is supplied to the laser diode 3. .

Here, the comparator 7 does not operate unless the power is turned on. Therefore, when the power is not turned on, the switch 2 remains off, the input frequency-multiplexed signal is not supplied to the laser diode 3, and reverse bias is not applied.

When the power is turned on, the comparator 7 is activated, the frequency-multiplexed signal is supplied, and the DC detection voltage of the pilot signal in the signal is higher than the reference voltage, so that the switch 2 is turned on. The optical output of the laser diode 3 is modulated by the frequency multiplexed signal.

Therefore, the optical transmitter having the above-mentioned structure takes out the pilot signal from the frequency-multiplexed signal and modulates the laser diode according to the comparison result of the DC voltage of the pilot signal and the reference voltage. When the power is not turned on, the comparison process is not executed, the frequency multiplexed signal is not supplied to the laser diode, and the laser diode is not reverse biased.

The present invention is not limited to the above-described embodiment, but is not limited to, for example, a pilot signal, and can be similarly implemented if a reference frequency signal of a specific frequency is multiplexed with an input frequency multiplexed signal. is there. Needless to say, various modifications can be made without departing from the scope of the present invention.

[0018]

As described above, according to the present invention,
It is possible to provide an electric / optical conversion device in which reverse bias is not applied to the electric / optical conversion element even when a frequency-multiplexed signal is input in a state where the device is not powered on.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an electrical / optical conversion device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional electric / optical conversion device.

[Explanation of symbols]

 1 Input Terminal 2 Switch 3 Laser Diode 4 Bandpass Filter 5 Amplifier 6 Detector 7 Comparator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04B 10/06 H01S 3/00 8934-4M 3/18

Claims (2)

[Claims] 1. An electrical / optical conversion device for converting a frequency-multiplexed signal in which a reference frequency signal is multiplexed into an optical signal, a switch for selectively deriving the frequency-multiplexed signal, and a reference frequency signal from the frequency-multiplexed signal. A filter for extraction, a detector for detecting the reference frequency signal extracted by the filter with a direct current, and a detector activated when the power is turned on and comparing the detection output of the detector with the reference voltage to find that the detection output is equal to or higher than the reference voltage. An electrical / optical conversion device comprising: a comparator that sets the switch to an ON state only when the above condition occurs, and an electrical / optical conversion element that converts the frequency-multiplexed signal derived by the switch into an optical signal. 2. The electrical / optical conversion device, wherein the reference frequency signal is a pilot signal of a specific frequency.