JPS6024921B2 - Optical axis alignment device for semiconductor laser and optical transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically aligns the optical axis between a semiconductor laser oscillator and an input end of an optical transmission line.

In recent years, with the promotion of practical use of optical communications, in order to efficiently provide the light emitted from a semi-moving body laser oscillator to an optical transmission path such as an optical fiber or self-occurring lens, it is necessary to align the optical axes of both to the point of maximum luminous intensity. It is occurring.

However, the light emitting area of the semiconductor laser oscillator is small, and
The diameter of the input end of an optical fiber is as small as about 60 microns, and the incident light must be a nearly parallel beam, making it extremely difficult to converge and convert the emitted light into parallel beams using an optical system. The following methods were used. FIG. 1 is a perspective view showing the optical axis adjustment situation for adjusting the relative position between the semiconductor laser oscillator and the input end of the optical transmission line. An optical transmission line 5 having input ends 4 directly facing each other is installed on a manipulator 6, and the operation of the manipulator 6 moves the optical transmission line 5 in the x and y directions, thereby connecting the semi-moving body laser oscillator 1 and the input end 4. Since the relative optical position with respect to the optical axis changes, the optical axis alignment must be adjusted.

Note that the output end 7 of the optical transmission line 5 is provided with an optical tome conversion element 9 that receives the output light 8, and the manipulator 6 is operated while monitoring this output to transmit the light to the maximum output point of the photoelectric conversion element 9. The position of path 5 is determined and optical fusion is performed. However, this method is inefficient because the operations are very delicate.
Furthermore, it has the disadvantage of poor accuracy, and a combination with a servo circuit shown in FIG. 2 is also used.

FIG. 2 is a block diagram when a servo circuit is used in conjunction with the servo mechanism 11 that drives the manipulator 6 in the x direction.
A feedback circuit 14 compares the output of the photoelectric conversion element 9 with the value held by a maximum output holder 13 that holds the maximum output of the photoelectric conversion element 9 and a servo mechanism 2 that drives in the y direction.
The difference between the two is alternately applied to the servomechanisms 11 and 12 by switching the gate circuit 15 to control the manipulator 6. Therefore, when the value held by the maximum output holder 13 and the output of the photoelectric conversion element 9 match, the output from the feedback circuit 14 becomes zero and the servo mechanisms 11 and 12 stop, but strictly speaking, even with this, complete light is not produced. There was a drawback that axis alignment was not possible. In other words, when the light emission power distribution of the semiconductor laser oscillator 1 is taken in the cross section in the direction of koji, there are multiple peaks for the luminous intensity 1 as shown in FIG.
When the maximum output holder 13 holds the value of , the one shown in FIG. 2 follows the peak P2 and stops at the peak P2.
The higher luminous intensity peak P, cannot be reached, and the optical axis alignment ends at a very inefficient point.

The present invention aims to solve the above drawbacks of the conventional art at once, and uses a servo mechanism that operates based on a sweep signal to adjust the relative position between the light emission of a semiconductor laser oscillator and the input end of an optical transmission line that directly opposes this light emission. At the same time, the maximum output of the photoelectric conversion element provided at the output end of the photoelectric transmission path is detected, the relative position corresponding to this output force is memorized, and the servo mechanism is activated based on this stored content. The present invention provides an extremely efficient optical axis alignment device between a semiconductor laser oscillator and an optical transmission line, which operates and automatically aligns the optical axis.

The details of the present invention will be explained below with reference to the block diagram of FIG. 4 showing an embodiment.

A switch SW as a switching circuit is inserted on the input side of the servo mechanisms 11 and 12 in the same figure, and by turning it to the A side, a pail pulling signal generator 21 generates a striped signal whose frequency component changes. , 22 are given, and the servo mechanisms 11 and 12 operate based on this sweep signal, and the manipulator 6 as an adjustment mechanism is applied in the x direction and the y direction, respectively.
In order to drive the light emission 3, scanning of the light emission 3 by the input end 4 is performed. On the other hand, the position of the manipulator 6 is in its x direction,
Electric signals are generated by position detectors 23 and 24 in the x and y directions using potentiometers or the like that rotate with movement in the y direction, and are sent to the terminal 2 via gate circuits 25 and 26.
7, and when the maximum output detector 28 detects the maximum output of the optical conversion element 9 by successive approximation, the gate circuits 25, 26 and the memory 27 are controlled by the detection power, and the maximum output detector 28 The positions of the manipulator 6 in the x and y directions when the position detector 28 detects the maximum output are written into the memory 27 according to the outputs of the position detectors 23 and 24, and are stored in this section.

Therefore, the status of the display ID such as an indicator that indicates the maximum output level of the photoelectric conversion element 9 that has been given to the maximum output detector 28 so far is monitored, and it is confirmed that the maximum output has been detected. After confirmation, when the switch SW is switched to B, the contents of the memory 27 are read out and the servo mechanism 11,
12, and the servo mechanisms 11 and 12 operate based on the contents of the memory 27, so the manipulator 6 moves to the position when the maximum output detector 28 detects the maximum output, and the maximum luminous intensity shown in FIG. The light fusion is completed at the peak P.

In addition, as for the sweep signal generators 21 and 22, the light emission 3 of the semiconductor laser oscillator 1 generally has a Gaussian distribution-like luminous intensity distribution characteristic, and as shown in FIG. etc., it is desirable to repeatedly perform optical axis alignment scanning by the mapulator 6 in the vicinity of the center of the light emission 3. For this purpose, the manipulator 6 is moved to the vicinity of the center of the light emission 3 by driving the servo mechanisms 11 and 12. It is preferable to use a sweep signal that generates a sweep signal that has a high frequency when the manipulator 6 moves to the vicinity of the light emitting device 3 and a low frequency when the manipulator 6 moves to the vicinity of the light emitting device 3. Although a variable frequency oscillator may be used for this purpose, it is also possible to use a sweep signal such as a noise generator or the like. A random signal generator is suitable.

That is, since the thermal noise caused by the temperature rise of the resistor has a Gaussian distribution characteristic, the servo mechanisms 11 and 12 are actuated by a noise signal with a frequency component corresponding to the response speed of the servo mechanisms 11 and 12, and the desired result is generated. You can reach your goal. In addition, various types of noise generators can be used as general fixed frequency oscillators or random number signal generators that generate random signals. Further, as the maximum output detector 28, a capacitor memory or the like having a large discharge time constant is used, and the value stored therein is constantly compared with the output of the optical force conversion element 9 using a comparator or the like, and the output is determined to be the stored value. The stored value may be updated when the output becomes larger than the stored value, and the detection force may be generated when the output starts to decrease below the stored value.

Therefore, the contents of the memory 27 are updated every time the maximum output detector 28 generates a detected force, but the manipulator output corresponding to the maximum output generated during scanning of the manipulator 6 by the servo mechanisms 11 and 12 within a certain period of time is updated. Since position 6 remains last, light merging is ensured at the point of maximum luminous intensity.

Note that it goes without saying that the longer the scanning period by the manipulator 6, the more reliable it is. In addition, a timer or the like may be provided to automatically switch the switch SW to B after a certain period of time; in this case, the display ID may be omitted.

Also, position detectors 23, 24, gate circuits 25, 26,
The configuration of the switch SW and the like and the insertion sites of the gate circuits 25 and 26 can be selected from various options, and can be arbitrarily determined depending on the conditions. In the above explanation, the optical transmission line 5 is connected to the manipulator 6 as an adjustment mechanism, but it goes without saying that the same effect can be applied even if the semiconductor laser oscillator 1 is movable. As is clear from the above explanation, according to the present invention, the optical axis alignment between the semiconductor laser oscillator and the optical transmission line, which has been extremely difficult, is automatically achieved, and moreover, it is always set at the point of maximum luminous intensity, so it is possible to do so reliably and It is highly accurate and can bring about great effects such as reducing adjustment man-hours and improving performance in the production of such devices.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a situation in which optical fusion is performed between a semiconductor laser oscillator and an optical transmission line, Figure 2 is a block diagram showing a conventional example of a servo circuit added to the one in Figure 1, and Figure 3 is a semiconductor laser oscillator. FIG. 4 is a block diagram showing an embodiment of the present invention. 1... Semiconductor laser oscillator, 3... Light emission, 4...
Input end, 5... Optical transmission line, 6... Manipulator (
adjustment mechanism), 7...output end, 9...photoelectric conversion element,
1 1, 12... Servo mechanism, 21, 22... Sweep oscillator, 23, 24... Position detector, 27... Memory, 28... Maximum output detector, SW... Switch (
switching circuit). Figure 1 Figure 2 Figure 3 Figure Dimensions

Claims (1)

[Claims] 1. In an optical axis alignment device for emitting light from a semiconductor laser oscillator and an optical transmission line that receives the emitted light, the optical relative position between the emitting light from the semiconductor laser oscillator and the input end of the optical transmission line directly facing the emitting light is determined. an adjustment mechanism that performs adjustment, a sweep signal generator that generates a sweep signal whose frequency component changes, and a servo mechanism that drives the adjustment mechanism based on the sweep signal;
a maximum output detector that successively compares the output of a photoelectric conversion element provided at the output end of the optical transmission line to detect the maximum output of the photoelectric conversion element; and a position detector that detects the position of the adjustment mechanism as an electrical signal. a memory that stores the position of the adjustment mechanism when the maximum output detector detects the maximum output according to the output of the position detector; What is claimed is: 1. An optical axis alignment device for a semiconductor laser and an optical transmission line, comprising a switching circuit for applying contents to the servo mechanism, and automatically aligning the optical axis.