JPH02183429A - Optical pickup for recording and reproducing information - Google Patents

Abstract

PURPOSE:To adjust a position relation of a laser light source and a thin film waveguide by providing a guide plate between the thin film waveguide and its holder so that the waveguide can be brought to linear movement freely. CONSTITUTION:A thin film waveguide substrate 8 of an optical pickup is held by a holder 1 through guide plates 11, 12. These guide plates 11, 12 can be brought to linear movement freely against the holder 1 along a projecting part 1b, etc., of the holder 1 and its movement is brought to feedback control through a piezo-element, etc. In such a way, a position adjustment of a semiconductor laser chip 4 fixed to a T-type mount 2, and an optical waveguide of the substrate 8 provided with an optical collimation use geodesic lens 9, a comb line electrode 10 for generating a surface acoustic wave for polarizing a collimated light, etc., is executed easily and surely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical pickup for recording and reproducing information, and is particularly suitable for recording and reproducing information using a device such as an optical disk in a field that handles a large amount of information. Regarding optical pickups.

[Prior art] Conventional devices have a hybrid structure of a light source and a thin film waveguide, as described in Japanese Patent Application Laid-open No. 85637/1982, but the main focus has been on the configuration of the functions of individual components. .

[Problem to be solved by the invention] The above-mentioned conventional technology does not take into consideration the adjustment and assembly technology between the light source and the thin film waveguide, and there is a problem in terms of whether assembly can actually be carried out efficiently. .

An object of the present invention is to provide an optical pickup that can be easily adjusted and assembled by taking into consideration the alignment of the light source and the thin film waveguide.

[Means for solving the problem] The above object is achieved by adding an adjustment member that allows fine movement between the semiconductor laser that is the light source and the thin film waveguide.
It can be achieved.

[Function] A semiconductor laser serving as a light source is fixed to the base substrate. The substrate of the thin film waveguide is held against this base by the frictional force of the holding member.

When aligning with the light source, install a new adjustment jig and flex the holding member in the direction of loosening the frictional force that fixes the base and waveguide substrate to align with the light source. , When it is completed, it is fixed again by restoring the frictional force to finish the assembly.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2.

A T-shaped mount 2 is attached to the mounting surface of the holder 1, and a semiconductor laser chip 4 is attached to the upper surface of the T-shaped mount 2 via a submount 3. Lead wires 5 from the semiconductor laser chip 4 are bonded to lead terminals 7 fixed to the T-mount 2 via an insulating plate 6. Also.

In the holder 1, a waveguide substrate 8, in which a thin film waveguide is formed using a material such as lithium niobate with titanium diffused through guide plates 11 and 12, is a member that extends from the holder 1 on both sides and uses frictional force. Retained. A geodisic lens 9 is formed on the waveguide substrate 8 to convert the emitted light 101 from the semiconductor laser chip 4 into parallel light.

Furthermore, a comb-shaped electrode 10 that generates a surface acoustic wave 102 to deflect the light that has been guided as parallel light is formed by a method such as vapor deposition. The light is several hundred M into the comb-shaped electrode 10.
Surface acoustic wave 1 generated when applying a high frequency of about Hz
When passing through the portion 02, the light is subjected to the action of diffraction and is separated into a 0th-order light 103 that travels straight and a 1st-order diffracted light 104 that is deflected. By changing this frequency, the direction of the first-order diffracted light 104 can be changed.

The thickness of the waveguide formed on the waveguide substrate 8 is approximately 1 μm, and the active layer of the semiconductor laser chip 4 must be aligned within this range to guide light. Furthermore, since the light 101 emitted from the end face of the semiconductor laser chip 4 spreads in a Gaussian distribution, it is necessary to bring it as close to the waveguide end face as possible in consideration of efficiency, and to make it on the order of 1 μm.

As a method, constrictions 1-a are made on the left and right sides of the holder 1 to make it flexible, and a piezo element 13, for example, is inserted into the space up to the waveguide substrate 8, and the friction between the holder 1 and the waveguide substrate 8 is A voltage is applied in the direction that reduces the force.

In this state, as shown in the longitudinal cross-sectional view in Fig. 2, the holder 1
An intermediate member 14 is extended from a fine movement table 15 through an opening in the bottom surface and connected to the waveguide substrate 8.The fine movement table 15 is movable in two axes orthogonal to the fine movement table 17 by a guide 16, and the semiconductor laser The waveguide substrate 8 is moved to a position where the emitted light 101 is guided by the second piezo element 18 that adjusts the gap with the chip 4 and the third piezo element 19 that adjusts the height. The holder 1 is engaged with the guide plates 11 and 12 by the protrusions 1-b and 1-b', and can be moved linearly by the guide grooves. Then, it is brought close to the semiconductor laser chip 4. Next, the waveguide substrate 8 is moved in the vertical direction using the third piezo element 19. The waveguide substrate 8 includes projections 11-a and 11-b of the guide plate 11 and a projection 12-a of the guide plate 12.

By engaging with 12-b, linear movement in the vertical direction is possible. When the light from the semiconductor laser chip 4 reaches the position with good waveguide efficiency, the voltage of the first piezo element 13 is lowered to eliminate the bending force on both sides of the holder 1, and the waveguide substrate 8 is Restore the holding force and complete the fixation. If the protrusions of the guide plates 11 and 12 are made to have smoother sliding by pasting or coating a material with a low coefficient of friction such as fluororesin, minute movements can be made easier.

According to this embodiment, the guide plates 11 and 12 allow two orthogonal
Adjustment is easy because it can be moved repeatedly in the axial direction, and since there are no mechanically moving parts after adjustment, highly reliable assembly can be achieved.

Another embodiment will be described with reference to FIGS. 3 and 4. In order to read the information recorded on the information recording disk, an optical system is required to collect and detect the light emitted from the thin film waveguide.

The first-order diffracted light 104 emitted from the end face of the waveguide substrate 8 is returned to parallel light by the cylindrical lens 20, and passes through the diffraction grating 21, thereby forming three spots for obtaining track information. The light passes through a deflection beam splitter 22, a 1/4 wavelength plate 23, and an objective lens 24 whose focal position can be changed by a lens drive coil 25, and is focused on an information recording disk 26. The reflected light changes its polarization direction by passing through an objective lens 24 and a quarter wavelength plate 23, is guided to a condensing lens 27 by a polarizing beam splitter 22, and a signal is detected by a detector 28. . This optical system is arranged on a substrate 29, and a thin film waveguide 8
Thereafter, the reference plane of the substrate 29 is used to form an integral structure so that no adjustment is required.

The T-type mount 2 that fixes the semiconductor laser chip 4 has a slight groove formed on the end surface side of the waveguide substrate 8, and the semiconductor laser chip 4 is placed in the groove by 1~ The board 29 is assembled at a position inclined about 3" and about 1 to 2 .mu.m inward from the end surface of the T-shaped mount 2. The substrate 29 is fixed to the holder 1 via guide plates 11 and 12.

During assembly and adjustment, the substrate 29 on which the entire optical system is mounted is slightly moved relative to the semiconductor laser chip 4 using a fine movement table as shown in FIG. In this embodiment, the guide plate 1 is directed toward the T-shaped mount 2 fixed to the holder 1.
An appropriate gap between the semiconductor laser chip 4 and the end surface of the waveguide substrate 8 can be achieved by simply bringing the components 1 and 12 close to each other using a fine movement table shown in FIG. 2 and bringing them into contact with the end surface of the T-shaped mount 2. Thereafter, the substrate 29 is slightly moved in the vertical direction using a third piezo element or the like. In order to find the optimal position, the information recording disk 26 or a reflector plate is placed at an appropriate position determined in advance in relation to the objective lens 24, and adjustment can be made by monitoring the amount of light entering the detector 28. becomes. When the amount of light is at its maximum, the frictional force between the holder 1 and the substrate 29 is restored in the same manner as in the first embodiment, and the fixation is completed.

According to this embodiment, since the end face of the semiconductor laser chip 4 and the end face of the waveguide substrate 8 are attached at an angle, the influence of noise due to the return light from the end face of the waveguide substrate 8 can be reduced, and the T-shaped Since the mount 2 serves as a reference plane and only needs to be brought into contact with the end surface of the waveguide substrate 8, alignment can be easily performed.Furthermore, if the inclination angle of the semiconductor laser chip 4 is the Bragg angle, Since it is sufficient to make the comb-shaped electrodes 10 parallel to each other, it is easy to make one. Further, since the detector 28 for signal detection can be used to confirm alignment, a measuring device for adjustment is not required, and there is an effect that adjustment can be easily performed.

[Effects of the Invention] According to the present invention, it is possible to easily perform minute alignment adjustments between a semiconductor laser as a light source and a thin film waveguide, and to guide light with optimal utilization efficiency. , re!
It has the effect that F1ml and exchange can be done easily.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is a vertical sectional view of Fig. 1, Fig. 3 is a plan view of the second embodiment, and Fig. 4 is a side view of the second embodiment. It is a diagram. 1...Holder 1-a...Neck part 1-b
...Protrusion 2...T-type mount 3...Sub-remount 4...Semiconductor laser chip 5...Lead wire 6...M edge plate 7...Lead terminal
8... Waveguide substrate 9... Geodisic lens
10... Comb-shaped electrode 11... Guide plate
11-a...Protrusion 11-b...Protrusion 12
...Guide plate 12-a...Protrusion 12-b...
Projection 13... Piezo element 14... Intermediate member 1
5... Fine movement table 16... Guide 17... Fine movement table 18... Piezo element 9... Piezo element 1... Diffraction grating 3... 174 Wave plate 5... Lens drive coil 7 ...Condensing lens 9...Substrate 01...Outgoing light 03...0th order light...Cylindrical lens...Polarized beam subrifter...Objective lens...Information recording disk...Detection Device 102...Surface acoustic wave 104...1st order diffracted light 'f3z'th

Claims (1)

[Claims] 1. A semiconductor laser light source provided on a base that also serves as a heat sink, a thin film waveguide, a geodisic lens for collimating the light emitted from the semiconductor laser light source, and for deflecting the collimated light. A guide plate is provided between the thin film waveguide and a holder that holds it to enable linear movement, and the position of the semiconductor laser light source and the thin film waveguide is An optical pickup for recording and reproducing information, characterized in that the relationship can be adjusted. 2. The optical pickup for recording and reproducing information according to claim 1, wherein the alignment between the semiconductor laser light source and the thin film waveguide is performed by a fine movement mechanism added to the holder only at the time of alignment. 3. The optical pickup for recording and reproducing information according to claim 1 or 2, wherein the output surface of the semiconductor laser light source is inclined by about 1 to 3 degrees with respect to the input surface of the thin film waveguide.