JPS6282833A - Laser transmission equipment - Google Patents

Abstract

PURPOSE:To keep the intensity of laser light constant so that digital optical communication can be executed without error by inverting the polarity of an amplified electric signal, inputting the inverted signal to an integrator together with a reference signal and integrating a difference between both the signals. CONSTITUTION:When a pulse input signal 1 is inputted, a laser diode 3 radiates laser light 4 on the basis of a pulse control signal 2 and a photodiode 5 receives the light 4 and converts the light 4 into the 1st electric signal 6. An amplifier 7 amplifiers the signal 6 and outputs the 2nd electric signal 8 proportional to the signal 6 and a polarity inverter 13 inverters the polarity of the signal 8 and outputs an inverted signal 14. A reference voltage generator 9 generates a reference signal 10, the signal 14 is inputted to the integrator 15 together with the signal 10, the difference between both the signals 14, 10 is integrated, and the integrated signal is outputted as a feedback signal 12. Consequently, the generation of an oscillating phenomenon in a control system is suppressed and a stable feedback signal can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a laser transmitting device having a laser diode, and in particular, converts laser light output from the laser diode into an electrical signal using a photodiode in the device. By increasing or decreasing the pulse control signal that controls the laser diode by converting it into It is characterized by being kept constant.

[Conventional technology]

As a conventional dan transmitting device, there is one shown in FIG.

In Fig. 3, (1) is the pulse input signal, (2) is the pulse control signal obtained by subtracting the feedback signal t13 from the pulse input signal (1), and (3) is the input of the pulse control signal (2). , a laser diode that generates laser light (4), (5) is a laser light (4)
a photodiode that converts the signal into a first electrical signal (6);
(7) amplifies the first electric signal (6) and generates the first j, I
an amplifier outputting a second electrical signal (8) proportional to the electrical signal 6);

0υ is the second electric signal (8) and the reference voltage generator (9)
This is a differential amplifier which amplifies the difference between the second electric signal (8) and the reference signal H by inputting the reference signal OI outputted by the reference signal OI and outputs the resultant signal as a feedback signal (Iz).

FIG. 4 shows the inside of the differential amplifier Uυ shown in FIG. 3.

R1 is the first resistor, R2 is the second resistor, Ul is the operational amplifier, (8+, (1(1, ([2 is the same as shown in the third factor).

below,! 1] Describe the work in detail. In fig.

When the pulse input signal (1) is input to if, the pulse control signal (2) causes the laser diode (3) to generate a laser beam (4), and at the same time the photodiode (5) in the device generates a laser beam ( 4) and converts the laser beam (4) into a first electric signal (61K i.
In step 7), the first electrical signal (6) is amplified and a 20' pulse signal (8) proportional to the first electrical signal (6) is output. On the other hand, a reference voltage generator (9) in the device generates a reference signal αl.
The second electric signal (8) is input to the differential amplifier αυ together with the reference signal α value and compared. As shown in FIG. 4, in the differential amplifier αυ, the second electrical signal (8
) via the first resistor R1, and the reference signal αG via the second resistor R1.
The two signals are led to the operational amplifier U1 via the resistor R2, and the magnitudes of both signals are compared in the operational amplifier UI, and the -difference is amplified and output as a feedback signal a3.

Now, the pulse input signal (1) and the feedback signal (Iz in Fig. 3 have opposite polarity to each other. When a large pulse input signal (1) is input, the feedback signal u3 increases and the pulse input Pulse control signal (2) created by subtracting the feedback signal @ from signal (11)
is controlled to a constant value.

[Problem that the invention seeks to solve]

In the conventional laser transmitter, the differential amplifier αυ that generates the pulse input signal (1) and the feedback signal α2 of opposite polarity was configured as a two-person differential amplifier with linear customization and operated as a two-power differential amplifier. When the change in 4) is slow, the second electrical signal (
8), the response of the feedback signal (13) is stable and the desired feedback signal t12 is obtained, but for the second electrical No. 43 (8) that changes rapidly, the differential amplifier αD There was a problem in that the operation was accompanied by an oscillation phenomenon, the feedback signal α2 fluctuated unstably, and the intensity of the laser beam (41) could not be kept constant.

This invention was made to solve this problem, and when the laser light changes rapidly, it provides a stable feedback signal even for the second electrical signal that changes rapidly with the change. The purpose of this output is to maintain the intensity of the laser light at a constant level so that digital optical communication can be performed without error.

[Means for solving problems]

The laser transmitting device according to the present invention inverts the polarity of the second electrical signal output by the amplifier using a polarity inverter to generate an inverted signal, and simultaneously sends a retransmission signal and a reference signal to an integrator in the device. The pulse input signal is input, the integrator integrates the difference between the inverted signal and the reference signal, and the integrated feedback signal is applied to the pulse input signal.

[Effect]

In this invention, the polarity of the second electrical signal outputted by the amplifier is inverted by a polarity inverter to create a 2-inverted signal,
Since the difference from the reference signal is integrated using an integrator and a feedback signal is output, control is possible even when the intensity of the laser light changes suddenly and the second electrical signal changes rapidly accordingly. The system does not cause oscillation and can output a stable feedback signal, controlling the pulse control signal to a constant value.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention,
(1) to αl and 0 are exactly the same as the above conventional device. αj is a polarity inverter that inverts the polarity of the second electrical signal (8) and outputs it as a 1-inverted signal I.

Ll! 19 is an integrator that simultaneously inputs the 2-inverted signal I and the reference signal α, integrates the difference between the 1-inverted signal (14) and the reference signal (11), and outputs it as feedback (No. 3 (1z). The figure shows the inside of the integrator U shown in FIG. 1. 1. IIJ and αL (14) are the same as those shown in FIG.

R1, R2, Ul are the same as shown in Fig. 4, R3
is the third resistor, and C1 is the capacitor.

The operation will be explained below. In FIG. 1, when a pulse input signal (1) is input to the device, a pulse control signal (2) is input to the device.
Therefore, the laser diode (3) emits laser light (4)
At the same time, a photodiode (5) within the device receives the laser light (4) and converts the laser light (4) into a first electrical signal (6). The amplifier (7) amplifies the first electrical signal (6) and outputs a second electrical signal (8) proportional to the first electrical signal (6). Polarity inverter (13
Then, the polarity of the second electric signal (8) is inverted and a 1-inverted signal I is output. On the other hand, a reference voltage generator (9) within the device generates a reference signal α1, and the 2-inverted signal I is input to an integrator α9 together with the value of this reference signal α.

As shown in FIG. 2, in the integrator (l), the 2-inverted signal α is routed through the first resistor R1, and the reference signal α is routed through the second resistor to the operational amplifier U1. Since the 2-inverted signal (14) has now passed through the polarity inverter (8), it also has the opposite polarity to the reference signal α1, and the operational amplifier U
When the positive terminals of the two signals are input simultaneously, the operational amplifier U1 integrates the difference between the two signals by the power storage action of the capacitor C1, and outputs it as a feedback signal α.

In the groove-bottomed laser transmitter as described above,
An integrator that outputs a feedback signal αa is
Due to the power storage action of the capacitor C1, the human power signal is integrated and output, so when the rapidly changing inverted signal α is input to the integrator, the integrator ae outputs the slowly changing feedback signal. (Outputs t2. If the feedback signal circle changes slowly, the control system will not be accompanied by an oscillation phenomenon and a stable laser beam (4) can be obtained.

Incidentally, in the above description, the present invention is described for the case where a pulse input signal is applied, but it goes without saying that the present invention can also be applied to cases where a trapezoidal wave input signal or input signals of other shapes are applied.

〔Effect of the invention〕

As explained above, the present invention inverts the polarity of the second electrical signal output from the amplifier using a polarity inverter.
By generating an inverted signal, inputting it to an integrator together with a reference signal, and integrating the difference between the inverted signal and the reference signal, it is possible to suppress oscillation phenomena in the control system of the device and obtain a stable feedback signal. There is.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing the inside of the integrator in FIG. 1. FIG. 3 is a diagram showing an example of a conventional laser transmitter. FIG. 4 is a diagram showing the inside of the differential amplifier in FIG. 3. In the figure, (1) is a pulse input signal, (2) is a pulse control signal, (3) is a laser diode, and (4) is a laser beam. (5) is a photodiode, (6) is a first electrical signal,
(7) is an amplifier, (8) is a second electric signal, (9) is a reference voltage generator, αC is a reference signal, υ is a differential amplifier, (
12 is a feedback signal, (I3 is a polarity inverter, a
< is an inverted signal. C9 is an integrator, R1 is the first resistor, and R2 is the second resistor. R3 is a third resistor jC1 is a capacitor, and U+ is an operational amplifier. Note that the same reference numerals in each figure indicate the same or corresponding parts.
Agent Masu Oiwa Base tube 1 Figure 2

Claims (1)

[Claims] a laser diode that outputs laser light by inputting a pulse control signal obtained by subtracting a field bank signal from a pulse input signal; a photodiode that converts the laser light into a first electrical signal; an amplifier that amplifies an electrical signal and outputs a second electrical signal proportional to the first electrical signal; a polarity inverter that inverts the polarity of the second electrical signal and outputs it as an inverted signal; A laser transmitter comprising an integrator that receives a signal and a reference signal output from a reference voltage generator, integrates the difference between the inverted signal and the reference signal, and outputs the result as the feedback signal. Device.