JP2001111154A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase mounting position precision of a member constituting a semiconductor laser device and reduce a time required for adjustment. SOLUTION: In a hologram laser having a semiconductor laser element 4, a hologram element 1 having a hologram 1b, a signal detecting photodetector 2, and a laser output monitor photodetector 5a, the semiconductor laser element 4, the hologram element 1, and the signal detecting photodetector 2 are mounted on the same block 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device having a hologram (hereinafter, referred to as a hologram) incorporated in an optical pickup used in an optical disk system such as a compact disk system and a video disk system.
Hologram laser). In particular, the hologram element diffracts the light from the semiconductor laser element that has been reflected back to the optical disk, and separates the tracking signal, focus signal, recording signal, etc., for accurately reading out the recording signal. The present invention relates to a hologram laser which can be guided to a processing integrated circuit to obtain an output signal.

[0002]

2. Description of the Related Art FIG. 6 shows a schematic configuration of a conventional hologram laser 100. In this figure, wiring relations are omitted for simplicity.

In the hologram laser 100,
A semiconductor laser element 4, a laser output monitoring light-receiving element 5a integrated submount 5, and a signal detection light-receiving element 2 are mounted on a metal block 3, and a hologram element 1 is covered with a cap 6 covering the block 3. Is mounted on the top surface 6a. The cap 6 is provided on the upper surface 7a of the eyelet 7, and the block 3 is formed integrally with the upper surface 7a of the eyelet 7.

[0004] The hologram element is usually made of a material having good light transmission characteristics, such as glass or acrylic resin.
In this hologram element 1, usually, a hologram 1b
Are formed on the upper surface 1a.

[0005] The light receiving element 2 for signal detection is provided on a Si substrate.
A photodiode 2a divided into a plurality of light receiving sections is formed. Normally, a signal processing circuit is also formed integrally with the signal detecting light-receiving element 2, so that the signal detecting light-receiving element 2 is hereinafter referred to as an OPIC.

The OPIC 2 is arranged above the light emitting point A of the semiconductor laser element 4 so as not to be affected by the monitor light L emitted from the rear end face of the semiconductor laser element 4.

[0007] The hologram laser 1 thus configured
At 00, signal detection is performed using any of the + 1st-order diffracted light and the -1st-order diffracted light J and K diffracted by the hologram 1b among the signal light reflected and returned by the optical disk.

[0008]

In the following, the diffraction light used for signal detection will be described as K, and the unnecessary diffraction light as J.

In assembling and adjusting the hologram laser, the biggest problem is to adjust the position of the hologram element 1 as easily and accurately as possible so that the signal light K is incident on a specified position B on the OPIC 2. It is.

Here, a prescribed position B where the signal light K is incident
Is substantially determined by the position of the laser emission point A, the position of the hologram forming surface 1a, and the position of the OPIC 2.
Of these, the hologram element 1 is mounted on the top surface 6a of the cap 6, and cannot be adjusted in the height direction (z direction).

For this reason, for example, the OPIC 2 and the cap 6
In order to absorb the variation in the distance in the height direction, it is necessary to adjust the hologram element 1 by moving or rotating the hologram element 1 in the plane of the top surface 6a of the cap 6. However, in this case, the center of the hologram 1b and the position of the light emitting point A of the semiconductor laser element 4 are shifted, which causes a decrease in performance as a hologram laser.

Furthermore, it is necessary to absorb the change in the x direction of the signal light incident position B due to the parallel movement of the hologram element 1 by increasing the length in the x direction, for example, in the light receiving portion (photodiode 2a) of the OPIC 2. is there. As a result, it is necessary to increase the size of the light receiving section 2a of the OPIC 2, and the frequency response characteristic is reduced, so that there is a problem that it cannot be used in a high-speed optical disk system.

The emission point A of the semiconductor laser device 4 is:
At the time of optical design, it is designed to be located at the position of the rear focal point of the condenser lens (not shown), but at the time of actual assembly adjustment, the eyelet 7 which is the reference surface of the hologram laser 100 is
Is adjusted only by the height from the upper surface 7a.

Therefore, the position of the light emitting point A of the semiconductor laser device 4 in the height direction varies by the thickness variation of the block 3. Similarly, hologram 1b
Position varies by the variation of the height of the cap 6 and the thickness of the hologram element 1, and the position of the OPIC 2 varies by the variation of the thickness of the block 3 and the thickness of the OPIC 2.

This variation will be described in detail with reference to FIG.

The design value of the height from the reference plane 7a to the light emitting point A of the semiconductor laser element 4 is represented by z _1, and the standard deviation of the variation is represented by Δz ₁ . Similarly, OP from the reference plane 7a
The design value of the height of the signal light to the incident point B on the IC 2 is z ₂
The standard deviation value of the variation is Δz ₂ , the design value of the height from the reference surface 7 a to the hologram mounting surface (top surface) 6 a of the cap 6 is z _3, and the standard deviation value of the variation is Δz ₃ I do.

Assuming that the height from the hologram mounting surface 6a of the cap 6 to the hologram 1b (the surface 1a on which the hologram 1b is formed) is z ₄ and the standard deviation of the variation is Δz ₄ , the signal light from the hologram 1b to the OPIC 2 Standard deviation Δz of the variation of the distance z _{5 in} the z direction to the incident point B
_{5, Δz 5 = √ (Δz 2} 2 + Δz 3 2 + Δz 4 2) becomes (1).

In particular, since the cap 6 is manufactured by pressing a thin metal plate, the height variation Δz ₃ is large, which causes a long adjustment time for accurately determining the position of the hologram 1b. I was That is, when the position of the hologram element 1 is measured by image recognition or the like, the deviation is often too large with respect to the finally required accuracy, and the assembly process is complicated, such as performing a rough adjustment and then a final adjustment. Had become.

When the position adjustment between the hologram 1b and the OPIC 2 is completed, the standard deviation Δz ₆ of the variation of the distance z ₆ between the light emitting point A of the semiconductor laser element and the hologram 1b in the z direction is Δz ₆ = √ (Δz ₁ ² + Δz ₃ ² + Δz ₄ ² ) (2)

Therefore, the distance z ₆ between the light emitting point A of the semiconductor laser element and the hologram 1b in the z direction is also affected by the height variation Δz ₃ of the cap 6. As a result, if the positional relationship between the hologram 1b and the OPIC 2 is optimized, the positional relationship between the semiconductor laser element 4 and the hologram 1b may be deteriorated, and it is necessary to make adjustments to optimize both at the same time.

However, the dimensional variation to be considered at the time of design is not limited to the height direction (z direction), but also to the x direction and y direction.
It is necessary to consider variations in the direction, and there are also factors that cannot be excluded by the assembly adjustment, such as a change in the oscillation wavelength of the semiconductor laser device. In addition, not only the cap 6 and the hologram element 1 but also an allowable range (hereinafter referred to as a tolerance) of dimensional variation of members constituting other semiconductor laser devices must be reduced as much as possible, which makes it difficult to manufacture components. There was a problem of becoming.

Further, it is necessary to avoid taking time for assembly adjustment. That is, the deviation of the distance between the OPIC 2 and the hologram 1 from the design value can be reduced as much as possible by adjustment. However, if the adjustment is performed with high accuracy, the adjustment takes a long time and the manufacturing time becomes long. is not.

The present invention has been made to solve such problems of the prior art, and can improve the mounting position accuracy of members constituting a semiconductor laser device to shorten the time required for adjustment. It is an object of the present invention to provide a semiconductor laser device in which the accuracy required for each member is low, components can be easily manufactured, and further, the light receiving section of the OPIC can be made smaller and the speed of the optical disk system can be increased. .

[0024]

According to the present invention, there is provided a semiconductor laser device comprising: a semiconductor laser device; a hologram device having a hologram for diffracting light emitted from the semiconductor laser device, reflected outside, and returned; A signal detection light-receiving element that receives light diffracted by the hologram element and detects a signal, and the semiconductor laser element, the hologram element, and the signal detection light-receiving element are mounted on the same block; Thereby, the above object is achieved.

The block is preferably made of a material having excellent dimensional accuracy and dimensional stability.

The block may be made of metal, or ceramic, liquid crystal polymer or engineering plastic capable of forming a wiring pattern.

[0027] Of the ± 1st-order diffracted lights diffracted by the hologram, the diffracted lights that do not contribute to signal detection can be blocked by the top surface of the block so as not to directly enter the inside.

[0028] The hologram element may have the hologram on the surface on the semiconductor laser element side.

The semiconductor laser device may further include a laser output monitoring light receiving element on the rear end face side.

A partition may be provided between a portion where the semiconductor laser element is provided and a portion where the signal detecting light receiving element is provided.

[0031] The partition may be provided by opening a path portion where light used for signal detection, out of the light diffracted by the hologram, enters the signal detection light-receiving element.

The operation of the present invention will be described below.

In the present invention, the semiconductor laser element, the hologram element, and the signal detecting light receiving element are mounted on the same block, and the cap which cannot increase the dimensional accuracy is not used. The time required for adjustment is reduced. In addition, the accuracy required for each member can be reduced, and the light receiving section of the OPIC can be made smaller, so that the speed of the optical disk system can be increased.

By using a material having excellent dimensional accuracy and dimensional stability as the block, the mounting accuracy of the members can be further increased. In particular, when a metal is used, a temperature rise of the semiconductor laser element due to heat generation can be prevented to improve reliability, and further, a characteristic deterioration such as an increase in dark current due to a temperature rise of the OPIC can be prevented. Also, engineering plastics that can form wiring patterns, such as liquid crystal polymers, can be molded with high heat resistance, can be plated, and have good accuracy.
Mass productivity can be improved. Further, if a ceramic capable of forming a wiring pattern is used, a rise in temperature can be prevented, and mounting accuracy can be improved more than that of metal.

Of the ± 1st-order diffracted light diffracted by the hologram, the diffracted light that does not contribute to signal detection is blocked by the top surface of the block so that unnecessary light does not directly enter the light receiving portion of the OPIC. can do.

In the hologram element, since the hologram is formed on the surface on the semiconductor laser element side, there is no variation factor due to the thickness of the hologram element.
The mounting accuracy can be further increased.

The laser output may be monitored by further providing a light receiving element on the rear end face side of the semiconductor laser element.
In this case, a portion where the semiconductor laser element is provided,
If a partition is provided between the light-receiving element for signal detection and the portion where the light-receiving element for signal detection is provided, monitor light emitted from the rear end face side of the semiconductor laser element does not enter the OPIC, and good signal characteristics can be obtained.

The partition wall is formed by cutting and opening a path portion of the light diffracted by the hologram, the light used for signal detection being incident on the OPIC. Light is OP
It is possible to prevent the signal light from being incident on the IC, and to allow the signal light having a sufficiently high intensity to be incident on the OPIC. Therefore, S /
By increasing the N ratio, better signal characteristics can be obtained.

Further, by disposing the OPIC 2 below the light emitting point of the semiconductor laser device, it is possible to increase the distance between the hologram and the OPIC and keep the diffraction angle small.

[0040]

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

(Embodiment 1) FIG. 1 is a perspective view showing a schematic configuration of a hologram laser 200 of Embodiment 1, and FIG. 2 is a cross-sectional view taken along the line PP '. In FIG. 1, the hologram element 1 is omitted for simplicity.

The hologram laser 200 has a hologram using a top surface 31a as a reference surface on a block 31 on which a semiconductor laser element 4, a laser output monitoring light receiving element 5a integrated submount 5 and a signal detecting light receiving element 2 are mounted. Element 1 is also mounted. This hologram element 1
As in the case of mounting on the cap, the block 31 is fixed to the block 31 with an adhesive such as a UV resin. In FIG. 1,
B1, B2, and B3 are light receiving elements of the OPIC2. Although not shown, the leads may be wired by plating or another one may be added.

According to the configuration of the hologram laser 200, unlike the conventional hologram laser 100 shown in FIG. 6, a cap formed by pressing a thin plate that cannot achieve high dimensional accuracy is not used. Mounting accuracy can be increased. In addition, block 31
Semiconductor laser element 4, OPIC2, hologram element 1
Is mounted, and the top surface 31a of the block 31 is used as a reference surface, so that mounting accuracy can be further improved.

Hereinafter, this point will be described in detail with reference to FIG.

Since the semiconductor laser element 4 and the OPIC 2 are mounted with reference to the top surface (upper surface) 31a of the block 31, the distance z in the z direction from the reference surface 31a to the hologram 1b (the surface 1a on which the hologram 1b is formed) is set. _14, and the z-direction distance z ₁₂ to the entrance point B of the signal light from the reference plane 31a into OPIC2 is both from the specified value only varies from machine precision. Assuming that the standard deviations of the variations are Δz ₁₄ and Δz ₁₂ ,
Distance z _{15 in} the z direction from signal light incident point B to PIC 2
Is the standard deviation Δz ₁₅ of the variation amount of Δz ₁₅ = √ (Δz ₁₂ ² + Δz ₁₄ ² ) (3)

On the other hand, the semiconductor laser device
Distance z in the z direction to the light emitting point A of No. 4 ₁₁Fluctuation (variation
The standard deviation of Δz₁₁Then, the hologram 1b and
Distance z in the z direction from light emitting point A of semiconductor laser element 4₁₆of
Standard deviation of variation Δz₁₆Is Δz₁₆= √ (Δz₁₁ ^Two+ Δz₁₄ ^Two) (4)

Therefore, both of z ₁₅ and z ₁₆ are smaller in variation than the conventional hologram laser 100 described with reference to FIG. 7 because there is no variation in the thickness of the cap with large variation. Become.

That is, by directly mounting the hologram element 1 on the block 31, the distance between the hologram element 1 and the semiconductor laser element 4 and the distance between the hologram element 1 and the OPI
The variation of the distance in C2 is smaller than that of the conventional structure because there is no variation in the height of the cap, and the accuracy is further improved. The variation in the x and y directions can be improved if the material accuracy is improved by using a material such as ceramic. However, the effect differs depending on the shape of the external shape.

As described above, it is possible to reduce the factor of the variation in the cap height, and it is easy to mount the laser or the hologram by the reference plane alignment, so that the time required for the assembly adjustment can be shortened. Further, since no cap is provided, the number of parts can be reduced. Furthermore, the amount of adjustment movement for parallel or rotational movement of the hologram element within the plane of the top surface of the cap can be made smaller than before in order to absorb variations in the distance in the height direction between the OPIC and the cap. The displacement between the center of the hologram and the light emitting point A of the semiconductor laser element is small, and the performance as a hologram laser can be improved. Further, by reducing the variation factor in the height direction, it is not necessary to increase the size of the light receiving portion of the OPIC to absorb the change in the signal light incident position B in the x direction as in the related art.
Therefore, the size of the light receiving section can be reduced, and it is possible to cope with a high-speed optical disk system.

It is desirable that the block 31 be made of a material having excellent dimensional accuracy and dimensional stability. For example, a metal such as Cu or Fe, an engineering plastic such as a liquid crystal polymer or a polyphthalamide resin capable of forming a wiring pattern, or a ceramic such as AlN can be used, but is not limited thereto.

In this embodiment, since the cap is not used, the semiconductor laser element 4 is directly exposed to the outside air. However, the reliability of the hologram laser 200 is improved by improving the manufacturing technique of the semiconductor laser element 4. Is not impaired.

Further, in this embodiment, of the light diffracted by the hologram 1b, the diffracted light J which does not contribute to signal detection is made incident on the top surface 31a of the block 31 and cut off, thereby directly entering the package. I try not to. Such an arrangement can be easily set by the diffraction angle θ and the thickness d of the hologram element 1. That is, the x-coordinate of the intersection of the diffracted light J and the top surface 31a of the block 31 is calculated by x = d · tan θ (5).

In this embodiment, an example will be described in which the OPIC 2 is at the same level or higher than the height of the light emitting point A of the semiconductor laser element 4 and the hologram 1b is on the upper surface of the hologram element 1. are doing. In this case, the signal light K is diffracted by the hologram 1b, passes through the hologram element 1, and falls on the OPIC 2. In this case, light travels through the hologram, and the distance can be increased there, so that the block (stem) can be thinned. In the present embodiment, the thickness of the hologram element 1 is increased by using no cap as in the related art, but this does not cause a problem in characteristics. The use of a resin hologram or the like does not significantly affect the material cost.

(Embodiment 2) FIG. 4 is a perspective view showing a schematic configuration of a hologram laser 300 of Embodiment 2 of the present invention.

The hologram laser 300 is an OPIC
2 is disposed below the light emitting point A of the semiconductor laser element 4.

For this reason, a notch is provided in a path portion of the block 32 so that the signal light K passing through the hologram element 1 mounted on the upper surface 32 a of the block 32 is not blocked by the block 32. In this case, depending on the mounting position of the semiconductor laser element 4, there is a possibility that monitor light emitted from the rear end face of the semiconductor laser element 4 goes around the light receiving section of the OPIC 2. Therefore, except for the path of the signal light K, the space between the cavity housing the semiconductor laser element 4 and the part mounting the OPIC 2 is closed by the block 33,
It is shaded.

(Embodiment 3) FIG. 5A shows Embodiment 3 of the present invention.
1 is a perspective view showing a schematic configuration of a hologram laser 400, and FIG. 2 (b) is a sectional view thereof.

The hologram laser 400 is an OPIC
2 is disposed below the light emitting point A of the semiconductor laser element 4. The hologram element 1 mounted on the upper surface 33 a of the block 33 has a hologram 1 b formed on the lower surface, that is, on the light emitting point A side of the semiconductor laser element 4.

According to the present embodiment, there is no variation in the distance between the hologram 1b and the light emitting point A of the semiconductor laser element 4 due to the variation in the thickness of the hologram element 1.
Further, the positional accuracy can be improved.

Also in the present embodiment, a notch is provided in a path portion of the signal light K diffracted by the hologram 1 b so that the signal light K is not blocked by the block 33. Further, as shown in FIG. 5B, the cavity containing the semiconductor laser element 4 and the OPIC 2 are mounted so that the monitor light L emitted from the rear end face of the semiconductor laser element 4 is not irradiated to the light receiving portion of the OPIC 2. Block (partition wall)
It is closed at 33b.

Further, since the OPIC 2 is formed below the light emitting point of the semiconductor laser device, the hologram and the OPIC 2 are formed.
The distance from the IC 2 can be increased, and the diffraction angle can be kept small.

In the present embodiment, the hologram element 1 is thinner than the other embodiments. This is because the hologram is provided on the side of the semiconductor laser element, thereby affecting characteristics and manufacturing. Does not occur.

[0063]

As described in detail above, according to the present invention,
By mounting the hologram element on the block on which the semiconductor laser element or the OPIC is mounted, the mounting accuracy of the members can be increased and the time required for adjustment can be shortened.
In addition, since the precision required for each member may be reduced, parts can be easily manufactured. Further, since it is not necessary to enlarge the light receiving portion of the OPIC as in the conventional case, it is possible to cope with a high-speed optical disk system.

If a liquid crystal polymer, engineering plastic, ceramic, or the like capable of forming a metal or a wiring pattern is used as the block, the dimensional accuracy and dimensional stability can be further increased, and the reliability can be improved.

Of the ± 1st-order diffracted light diffracted by the hologram, the diffracted light not contributing to signal detection is blocked by the top surface of the block so that unnecessary light does not directly enter the light receiving portion of the OPIC. can do. Therefore, a signal can be read out more accurately.

By forming the hologram on the surface of the hologram element on the side of the semiconductor laser element, there is no variation factor due to the thickness of the hologram element, so that the mounting accuracy can be further improved. Further, by disposing the OPIC below the light emitting point of the semiconductor laser element, the distance between the hologram and the OPIC can be increased, and the diffraction angle of the hologram can be kept small. Therefore, the production can be stabilized by increasing the pitch of the hologram.

If a partition is provided between the portion where the semiconductor laser device is provided and the portion where the signal detecting light-receiving device is provided, the monitor light emitted from the rear end face side of the semiconductor laser device will be OPIC. Can be prevented. Therefore, a signal can be read out more accurately.

The partition wall is formed by cutting and opening a path portion of the light diffracted by the hologram, the light used for signal detection being incident on the OPIC, so that a monitor emitted from the rear end face side of the semiconductor laser element is formed. Light is OP
It is possible to prevent the signal light from being incident on the IC, and to allow the signal light having a sufficiently high intensity to be incident on the OPIC. Therefore, S /
By increasing the N ratio, better signal characteristics can be obtained, and signal light can be read out more accurately.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a hologram laser according to a first embodiment.

FIG. 2 is a sectional view taken along line P-P 'of FIG.

FIG. 3 is a diagram for explaining the mounting accuracy of members of the hologram laser according to the first embodiment.

FIG. 4 is a perspective view illustrating a schematic configuration of a hologram laser according to a second embodiment.

FIG. 5A is a perspective view illustrating a schematic configuration of a hologram laser according to a third embodiment, and FIG. 5B is a cross-sectional view thereof.

FIG. 6 is a sectional view showing a schematic configuration of a conventional hologram laser.

FIG. 7 is a diagram for explaining the mounting accuracy of members in a conventional hologram laser.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 hologram element 1 a upper surface of hologram element 1 b hologram 2 OPIC 2 a light receiving section of OPIC 3, 31, 32, 33 block 4 semiconductor laser element 5 integrated light-receiving element for laser output monitoring 5 a light receiving element for laser output monitoring 6 cap 6 a Upper surface of cap 7 Eyelet 7a Upper surface of eyelet 31a, 32a, 33a Upper surface of block 33b Partition wall A Light emitting point of semiconductor laser element B Point of incidence of signal light on OPIC J Diffracted light not used for signal detection K Used for signal detection Diffracted light

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01L 31/12 H01L 31/12 EF term (reference) 2H049 CA01 CA07 CA15 CA20 5D119 AA04 AA38 BA01 CA09 DA01 DA05 EA02 EA03 FA05 JA14 JC05 JC06 JC07 KA02 LB07 NA04 NA05 NA06 5F073 AB14 AB21 AB25 BA04 FA05 FA11 FA23 FA30 5F089 AA02 AB01 AC30 CA03 CA21 GA05

Claims (8)

[Claims] 1. A hologram element having a semiconductor laser element, a hologram for diffracting light emitted from the semiconductor laser element, reflected outside, and returned, and receives a signal diffracted by the hologram element to receive a signal. A semiconductor laser device comprising at least a signal detection light-receiving element for detecting a signal, wherein the semiconductor laser element, the hologram element, and the signal detection light-receiving element are mounted in the same block. 2. The semiconductor laser device according to claim 1, wherein said block is made of a material having excellent dimensional accuracy and dimensional stability. 3. The semiconductor laser device according to claim 2, wherein said block is made of metal, or ceramic, liquid crystal polymer or engineering plastic capable of forming a wiring pattern. 4. The ± 1st-order diffracted light diffracted by the hologram, wherein the diffracted light that does not contribute to signal detection is cut off at the top surface of the block so as not to directly enter the inside. 4. The semiconductor laser device according to any one of 3. 5. The semiconductor laser device according to claim 1, wherein the hologram element has the hologram on a surface on a side of the semiconductor laser element. 6. The semiconductor laser device according to claim 1, further comprising a laser output monitoring light receiving element on a rear end surface side of said semiconductor laser element. 7. The device according to claim 1, further comprising a partition wall between a portion where the semiconductor laser device is provided and a portion where the signal detection light receiving device is provided. Semiconductor laser device. 8. The signal processing device according to claim 7, wherein the partition wall is provided by opening a path portion where light used for signal detection, out of the light diffracted by the hologram, enters the signal detection light-receiving element. Semiconductor laser device.