JPS6251516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor laser excitation device that applies mechanical vibration of minute amplitude and constant frequency to a semiconductor laser.

By excitation of the semiconductor laser, it becomes possible to achieve fine deflection of the semiconductor laser beam or fine fluctuation of the spot position of the focused semiconductor laser beam using a lens system. One example of an important application of minute fluctuations in the spot position of semiconductor laser light is tracking of a disk surface in an optical information reading device such as a video disk. That is, as one method of tracking, in order to track the bit rows on the disk surface, a light spot focused on the disk surface is swung at a constant frequency and with an amplitude of about 0.1 to 0.2 μm in a direction perpendicular to the pit rows. A so-called wobbling method is often used. Conventionally, optical means such as vibration of a reflecting mirror have been used as means for wobbling, and this requires a dedicated optical element such as the reflecting mirror, which complicates the structure of the optical information reading device. was.

The present invention has been made in view of the above circumstances, and is characterized by focusing on the small size and light weight of semiconductor lasers, and by creating a small and simple cantilever structure without impairing these characteristics. A semiconductor laser is installed to realize excitation of the cantilever. Another feature is that metal is used as the material for the cantilever and its clamper, and the good thermal conductivity of the metal ensures heat dissipation from the semiconductor laser, thereby realizing stable laser oscillation. . Still another feature is that electrostrictive elements are pasted on both sides of the metal cantilever, and these are connected to an electric signal amplification section including a band amplifier and a phase shifter to cause self-oscillation of the cantilever, thereby achieving constant oscillation. The objective is to apply stable vibrations of constant amplitude and frequency to a semiconductor laser. The figures will be explained below.

FIG. 1 is a perspective view of a semiconductor laser excitation section.
In the figure, a semiconductor laser 10 is connected to a rectangular parallelepiped metal cantilever 3 via an auxiliary heat sink 20.
It is attached by brazing etc. near the tip of 0.
Thermal contact with the metal cantilever 30 is maintained. One side of the metal cantilever 30 is fixed by a clamper 40 made of the same metal material or separately processed metal.
Here, between the semiconductor laser 10 and the metal cantilever 30, and the metal cantilever 3
Thermal contact is maintained between the semiconductor laser 10 and the clamper 40, so that the heat generated by the semiconductor laser 10 is transmitted to the metal cantilever 30 and the clamper 40 and released to the outside world. The metal cantilever 30 is provided with electrodes on two opposite surfaces thereof, at a position different from the semiconductor laser 10, and which can be expanded and contracted in the length direction 50 of the metal cantilever 30 by an electrostrictive effect. A pair of electrostrictive element plates 60a and 60b are attached to each other. However, the electrostrictive element plate 60b is not shown in the figure. Lead wires 70a and 70b are drawn out from the electrodes of each electrostrictive element plate 60a and 60b that are not in contact with the metal cantilever 30, so that it is possible to take out the electrode voltage or apply voltage to the electrode. is being done.

FIG. 2 is a schematic explanatory diagram of a semiconductor laser excitation device according to the present invention. The electrostrictive element plate 60a is connected to the electrostrictive element plate 60a by a lead wire 70a drawn out from the electrostrictive element plate 60a attached to the metal cantilever 30.
The electrode voltage is input to the electrical signal amplification section 80. The electric signal amplification section 80 includes a bandpass filter 90, an amplifier 100, and a phase shifter 110, and outputs its output voltage to the electrostrictive element plate 60b via a lead wire 70b.
to be applied. Gain of amplifier 100, phase shifter 110
The phase shift amount is adjusted so that the tip of the metal cantilever 30 swings stably with a constant amplitude due to self-oscillation. The band filter 90 is tuned to one natural frequency of the metal cantilever 30, and is provided so that self-oscillation is performed at this frequency. As explained above, in the vibration device according to the present invention, since self-excited oscillation of the metal cantilever 30 is adopted, the natural frequency of the metal cantilever 30 may be slightly affected by temperature changes, etc. It will be easily understood that this has the advantage that even if it is changed, the amplitude and stability of the oscillation are hardly affected. Note that the bandpass filter 90 and amplifier 10 in FIG.
0. The order of the phase shifters 110 has no effect on the function of the vibration excitation device according to the present invention, and these orders may be changed freely. Although the bandpass filter 90 and the amplifier 100 have been described separately, it goes without saying that the vibration device according to the present invention can also be applied to a case where the bandpass filter and amplifier are integrated, such as an active bandpass filter.

As described above, according to the present invention, a semiconductor laser is attached to a small and simple metal cantilever so as to maintain thermal contact, and a pair of semiconductor lasers is attached to the metal cantilever. In order to excite the semiconductor laser by causing the metal cantilever to self-oscillate using an electrostrictive element plate, a band amplifier, and an electric signal amplification section including a phase shifter, the semiconductor laser is excited. Without sacrificing the features of small size and light weight, stable laser oscillation can be maintained due to good heat dissipation, and stable mechanical vibrations of constant amplitude and constant frequency can be applied to the semiconductor laser.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor laser excitation section, and FIG. 2 is a schematic explanatory diagram of a semiconductor laser excitation device according to the present invention. In the figure, 10 is a semiconductor laser, 30 is a metal cantilever, 40 is a clamper, 60 is an electrostrictive element plate, 80 is an electric signal amplification section, 90 is a bandpass filter, 100 is an amplification section, and 110 is a phase shifter.
In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A roughly rectangular parallelepiped metal cantilever that is made of the same metal material as the clamper that fixes one end, or is fixed to a clamper that is separately machined from a different metal member while maintaining thermal contact; A semiconductor laser is mounted near the tip of a metal cantilever while maintaining thermal contact by means such as brazing, and a semiconductor laser is attached to two opposing surfaces of the metal cantilever at positions different from the semiconductor lasers. , and is expandable and contractible in the length direction of the metal cantilever by electrostrictive effect.
a pair of electrostrictive element plates each having electrodes on both sides;
At least an amplifier with a bandpass filter and a phase change section are provided to amplify the voltage generated at the electrode of the first electrostrictive element plate of the pair of electrostrictive element plates on the side not in contact with the metal cantilever. an electric signal amplification section, and applies the output of the electric signal amplification section to an electrode of a second electrostrictive element plate of the pair of electrostrictive element plates on the side not in contact with the metal cantilever. A semiconductor laser excitation device characterized by inducing self-excited oscillation of the metal cantilever and transmitting vibrations at the tip of the metal cantilever due to the self-excited oscillation to the semiconductor laser.