JP2003037326A - Cap for semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cap for a semiconductor laser which enables miniaturization, improvement of optical performance and cost reduction of an optical system of an optical disk device or the like. SOLUTION: The cap for a semiconductor laser is provided with a metal cap main body 11 in which a window hole 11a for light transmission is formed in a ceiling plate 11b, and window plate glass 14 on which a phase difference film 13 is stuck via transparent adhesive agent 12 made of resin. The film 13 has phase difference λ/4 to a light source wavelength λ by optical anisotropy. The window plate glass 14 is made to adhere to the window hole 11a of a cap main body 11, via adhesive agent 15 made of resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser cap used in an optical system such as an optical disk device.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser used in an optical system such as an optical disk device has a structure as shown in FIG. The cap portion in the figure includes an annular top plate portion 1b having a circular window hole 1a formed in the center and a top plate portion 1b.
Having a tubular portion 1c extending from the outer periphery of the glass and an annular flange portion 1d extending outward from the open end of the tubular portion 1c has a coefficient of thermal expansion of glass such as Kovar (Fe-Ni-Co alloy). Consisting of a cap body 1 made of a metal similar to
A circular or polygonal window plate glass 2 is hermetically sealed on its inner surface with a low melting point glass 3 over the entire circumference of the window hole 1a.

Generally, the semiconductor laser as described above is
It emits linearly polarized laser light.

[0004]

DISCLOSURE OF THE INVENTION In recent years, CD-R and DV
With the increase in the recording density of optical discs such as D, it has been attempted to increase the S / N ratio and the efficiency in optical systems such as optical disc devices by utilizing the polarization characteristics of laser light. For example, as the polarization characteristics of laser light,
It is known that using elliptically polarized (including circularly polarized) laser light reduces the probability of optical disc read errors compared to using linearly polarized laser light. When converting emitted linearly polarized laser light into elliptically polarized (including circularly polarized) laser light, a wave plate made of a dielectric crystal typified by crystal is usually used.

When the laser light emitted from the semiconductor laser is elliptically polarized (including circularly polarized) as described above, it is necessary to incorporate the wavelength plate 4 into the optical system as shown in FIG. 2. Description of the Related Art With the downsizing and thinning of optical disk devices, etc., there is a strong demand for downsizing of optical systems, and it has become difficult to secure a sufficient space for disposing the wave plate 4.

Further, the wave plate 4 made of crystal or the like is expensive in material itself, and the dielectric crystal such as crystal or the like has high hardness and is difficult to process, and the number of parts is increased, so that the assembling cost is increased. There are also problems such as.

Further, a compact disc, abbreviated as CD
(CD-ROM, CD-R, CD-RW) and digital versatile disk, abbreviated as DVD (DVD-ROM, DVD-
In an optical system such as RAM, DVD-R, DVD-RW) which uses different light sources in one drive, it is necessary to prepare a wave plate having a phase difference of λ / 4 with respect to each light source wavelength λ. is there.

The present invention has been made in view of the above-mentioned problems of the prior art, and is to reduce the size of an optical system such as an optical disk device, to improve optical performance such as to cope with a plurality of different light source wavelengths,
Another object of the present invention is to provide a semiconductor laser cap that can be manufactured at low cost.

[0009]

A semiconductor laser cap according to the present invention comprises a cap body made of a metal having a window for light transmission formed in a top plate and a light source due to optical anisotropy on a light transmitting surface. A window plate glass having a resin retardation film having a predetermined retardation with respect to the wavelength λ attached via a resin transparent adhesive, the window plate glass being made of resin in the window hole of the cap body. It is preferable that the retardation film has a retardation of approximately λ / 4 with respect to the light source wavelength λ.

A resin retardation film used in the present invention;
If it has the same optical anisotropy as a birefringent crystal such as quartz,
Can be used, for example, to apply stress in one direction of the film.
And the film is refracted by the photoelastic effect of the residual strain.
The optical anisotropy is set in the index to produce the specified phase difference.
Things are common. With such a retardation film
When converting linearly polarized light to elliptically polarized light, see Figure 1.
As shown in FIG.
Z-axis (direction of extraordinary ray refractive index n _eHave
Direction) and X axis (ordinary ray refractive index n_oWith direction)
Electric field vibration plane at an angle of 45 ° to the X axis in the XZ plane
A linearly polarized laser beam L1 having D is incident. Phase difference
In the film 13, the Z-axis of the linearly polarized laser beam L1
Component that vibrates in the direction (called extraordinary ray) and vibrates in the X-axis direction
There is a difference in optical path length between the moving component (called ordinary ray)
Therefore, after passing through the retardation film 13, extraordinary rays and ordinary rays
The laser beam L1 is elliptically polarized due to the phase difference between the line and
It is converted into laser light L2. In particular, the phase difference is the light source wavelength
Linearly polarized laser if exactly λ / 4 for λ
-Because the light L1 is converted into circularly polarized laser light L2
Become.

Generally, a semiconductor laser chip emits linearly polarized laser light. Therefore, by using the semiconductor laser cap of the present invention, a semiconductor laser light source for emitting elliptically polarized or circularly polarized laser light can be easily manufactured. It becomes possible to do. In this case, it is important to arrange the retardation film 13 so that the direction (stress direction) having the extraordinary ray refractive index n _e and the electric field vibration plane D of linearly polarized light form an angle of about 45 °.

As a transparent adhesive, the cured product has an epoxy resin which has a sufficient light-transmitting property with respect to the light source wavelength λ and cures in a temperature range that does not adversely affect or deteriorate the optical characteristics of the retardation film 13. Any acrylic resin or other transparent resin can be used, and an ultraviolet curable adhesive is preferable because the retardation film 13 can be attached in a short time.

As an adhesive made of resin for fixing the window glass to the window hole of the cap body, epoxy-based, acrylic-based or other transparent adhesives that cure in a temperature range that does not adversely affect or deteriorate the optical characteristics of the retardation film 13 are used. It can be used if it is made of a suitable resin, and an adhesive with a proven and reliable epoxy type is preferable for hermetic sealing, and if it is an ultraviolet curable adhesive, the window glass can be used for a short time. It is more preferable because it can be attached by.

Further, in the semiconductor laser cap of the present invention, the retardation film attached to the window glass forms a retardation layer having a retardation of approximately λ / 4 with respect to a predetermined range of the light source wavelength λ. It is characterized by

The retardation layer formed by the retardation film attached to the window glass in the present invention is, for example, approximately λa / 4 for light in the range from λa of 655 nm to λb of 785 nm as the light source wavelength λ. ~ Any material having a predetermined retardation of approximately λb / 4 and having optical anisotropy can be used. Further, the retardation film constituting the retardation layer can be used if it has the same optical anisotropy as that of a birefringent crystal such as a crystal, and, for example, stress in one direction of the film, and light of its residual strain can be used. It is common that the refractive index of the film is provided with optical anisotropy by the elastic effect to produce a predetermined retardation. With such a retardation film, the light source wavelength of linearly polarized light is 655 nm and λ is 785 nm.
When the light of b is converted into elliptically polarized light, as shown in FIG. 2, it is the direction having the extraordinary ray refractive index n _o and the Z axis which is the direction having the extraordinary ray refractive index n _e of the retardation layer 23. 45 from the semiconductor laser with respect to the X axis in the XZ plane created by the X axis
A laser beam L1 having a field oscillation plane D at an angle of ° and a light source wavelength of 655 nm λa and 785 nm λb of linear polarization.
A and L1b are incident. In the retardation layer 23, the optical path length between the linearly polarized laser beams L1a and L1b that vibrate in the Z-axis direction (referred to as extraordinary rays) and the component that vibrates in the X-axis direction (referred to as ordinary rays). Since there is a difference, the retardation layer 2
After passing 3, the extraordinary ray and the ordinary ray have a phase difference, and the laser beams L1a and L1b are elliptically polarized laser beams L2.
a and L2b, respectively. Particularly, when the phase difference is exactly λa / 4 and λb / 4 with respect to λa of the light source wavelength of 655 nm and λb of 785 nm, the linearly polarized laser beams L1a and L1b are circularly polarized laser beams L2a and L2b.
Will be converted to.

In the retardation film constituting the retardation layer, the shorter the wavelength of the light source, the larger the retardation, which is the wavelength dispersion. Therefore, the retardation layer, a plurality of types of retardation film, by devising the bonding angle,
The phase difference is increased as the light source wavelength is increased.
Further, the retardation film constituting the retardation layer has optical anisotropy, and it can be used if the plane of polarization of the laser light passing therethrough can be circularly polarized light rotated by 45 degrees. It is preferable that the plane of polarization is rotated by 90 degrees in a reciprocating manner, and the subsequent polarization prism can separate the reflected light. Furthermore, it is more preferable that a retardation plate having a retardation of λj / 4 can be prepared in accordance with an arbitrary light source wavelength λj by changing the stretching amount of the retardation film. Further, as the adhesive constituting the retardation layer,
The cured product is sufficiently transparent to transmitted light, and JIS-K-6
If the Shore-A hardness specified in 301 is about 70, it can be used, and in order to reduce the assembly cost, it is preferable to use an ultraviolet (hereinafter referred to as UV) curable resin.

Further, in the semiconductor laser cap of the present invention, the window glass has a Ra value of the surface roughness of the light transmitting surface of 0.5.
and the retardation film is characterized in that the Ra value of the surface roughness of the outer light-transmitting surface is 1.5 nm or less, and the laser light is transmitted through the φ1.5 mm region of the window glass. The rms value of the wavefront aberration that occurs when
It is preferably nm or less.

The glass plate used as the window glass in the present invention can be used if the light-transmitting surface has an Ra value of 0.5 nm or less, which is an arithmetic average surface roughness defined by JIS-B-0601. is there. When the Ra value of the surface roughness exceeds 0.5 nm, the transmitted light is scattered on the surface of the glass plate, so that there is a concern that the optical signal that arrives may decrease and the S / N ratio may decrease. Further, the plate thickness of the glass plate is preferably 0.2 mm or more in order to maintain its mechanical strength and flatness. As the glass used for the glass plate, when the absorption of the transmitted light is large, the optical signal that arrives is reduced and the S / N ratio is lowered. Therefore, the light transmittance in the emission wavelength range of the light source is preferably 91% or more. .

If the surface roughness of the outer light-transmitting surface of the retardation film attached to the light-transmitting surface of the window glass with a transparent resin adhesive is 1.5 nm or less in Ra value, it is used. It is possible. When the Ra value of the surface roughness exceeds 1.5 nm, the transmitted light is scattered on the surface of the glass plate to reduce the optical signal, and the S / N ratio may decrease.

Here, φ1.5 mm of the transparent surface of the window glass
The rms value of the transmitted wavefront aberration that occurs when the laser light passes through the region is 13 nm or less means that when the light source wavelength λ of the transmitted wavefront aberration measuring device is 632.8 nm, r
This means that the ms value is 0.02λ or less. The rms value of the transmitted wavefront aberration of the window glass is 13 nm, that is, 0.02.
When λ is exceeded, the coherence of the transmitted light is reduced and the spatial and temporal spread occurs, resulting in the S / N of the optical signal.
There is a problem that the ratio decreases, but the transmitted wavefront aberration r
If the ms value is 13 nm or less, such a problem does not occur, and it can be used for an optical system such as a high density optical recording medium that requires high coherence for transmitted light.

Further, the semiconductor laser cap of the present invention is characterized in that the window glass is substantially quadrangular, and the window glazing is adhered to the window hole of the cap body having the substantially quadrangular top plate portion. To do.

The cap main body having a substantially quadrangular top plate portion may be a substantially rectangular shape such as a substantially square shape or a substantially rectangular shape, and the cylindrical portion extending from the outer periphery of the top plate portion also has a substantially rectangular cross section. . Further, as the substantially quadrangular window glass, it can be used as long as it can be fitted into the cap body having the substantially quadrangular top plate portion, and one side thereof and the stress direction of the resin retardation film are parallel to each other, It is preferable that they are attached at a predetermined angle such as vertical or 45 °.

[0023]

The semiconductor laser cap of the present invention comprises a metal cap body having a window for light transmission formed in the top plate,
A window glass having a resin-made retardation film having a predetermined retardation with respect to a light source wavelength λ due to optical anisotropy on a light-transmitting surface, which is attached via a resin-made transparent adhesive. Of the linearly polarized light emitted from the semiconductor laser chip and the direction (stress direction) of the retardation film having the extraordinary ray refractive index n _e of the retardation film. By arranging so that the laser beam electric field vibration surface is at an angle of 45 °,
Elliptically polarized laser light can be easily obtained. In particular, the phase difference after passing through the phase difference film is the light source wavelength λ.
On the other hand, when λ / 4 is accurate, linearly polarized laser light can be converted into circularly polarized laser light.

Further, in the semiconductor laser cap of the present invention, the retardation film attached to the window glass forms a retardation layer having a retardation of approximately λ / 4 with respect to a predetermined range of the light source wavelength λ. Therefore, one window glass can be used for many optical systems such as an optical disc device having a plurality of light sources having different wavelengths, a low-pass filter for a video camera device, and the like.

Further, in the semiconductor laser cap of the present invention, the window glass has a Ra value of the surface roughness of the transparent surface of 0.5.
Since the Ra value of the surface roughness of the outer light-transmitting surface of the retardation film is 1.5 nm or less, the thickness of the transparent adhesive for adhering the glass plate and the retardation film is substantially constant. Therefore, it is possible to reduce the transmitted wavefront aberration with a simpler structure than the conventional one.

Further, in the semiconductor laser cap of the present invention, since the rms value of the wavefront aberration generated when the laser light is transmitted through the φ1.5 mm region of the window glass is 13 nm or less, the S / of the transmitted optical signal is N ratio does not decrease, DV
It can be used in an optical system such as an apparatus using D (abbreviation of digital video disk) or other high density optical recording medium.

Further, in the semiconductor laser cap of the present invention, the window glass has a substantially quadrangular shape, and the window glass is adhered to the window hole of the cap body having a substantially quadrangular top plate portion. A window glass sheet having a shape in which the direction (stress direction) having the extraordinary ray refractive index n _e of the retardation film with respect to one side of the shape is set to a predetermined angle can be easily obtained, and the one side of the window glass sheet is substantially square. It is positioned parallel to one side of the top plate part of the shape, or the one side of the window glass is brought into contact with the inner wall surface of the cylindrical part whose cross section extending from the outer periphery of the top plate part has a substantially quadrangular shape, etc. With a substantially rectangular window glass positioned in place, it is adhered to the window hole of the top plate with a resin adhesive to give a predetermined optical anisotropy to one side of the substantially rectangular shape of the cap body. Keys for semiconductor lasers Tsu it is possible to obtain a flop.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a semiconductor laser cap of the present invention is shown in FIG. In the figure, a metal cap body 1
The top plate 1 is made of a metal having a thermal expansion coefficient of Kovar (Fe-Ni-Co alloy) similar to that of glass, and a circular window hole 11a with a diameter of 2 mm for light emission is formed in the center. 11b, a tubular portion 11c extending from the outer periphery of the top plate portion 11b, and an annular flange portion 11d extending outward from the open end of the tubular portion 11c. It is in the shape of a quadrangle having a side of 3.5 mm, a window hole 11a is formed therein, and the surface is plated with nickel having a thickness of about 2 μm to prevent oxidation. The top plate portion 11b of the cap body 11 has UV on the inner glass plate 10.
A retardation film 13 having a phase difference of λ / 4 with respect to a light source wavelength λ of 655 nm is attached via a transparent adhesive 12 made of (ultraviolet) curable resin, and a light source wavelength λ of 6
It is a quadrangle having a side of 3.4 mm and a thickness of 0.3, which has a light transmittance of 91% or more per thickness of 10 mm at 55 nm.
mm of window glass 14 made of borosilicate glass is UV
It is adhered via a curable resin adhesive 15. In addition, in order to increase the light transmittance, an antireflection film may be further formed on the outer surface of the window glass or the outer surface of the retardation film so as to match the light source wavelength λ.

Next, a method for producing the semiconductor laser cap of the present invention will be described.

First, the retardation film 13 is attached to the transparent adhesive 1
When the window glass 14 bonded with 2 is produced, for example,
As shown in FIG. 4, when the light source wavelength is 655 nm, the thickness 1
0.3m thickness with 91% or more transmittance per 0mm
m glass plate 10 made of borosilicate glass has a wavelength of 35
A transparent adhesive 12 made of UV curable resin having a low viscosity of 3000 mPas and having a sensitivity to 0 nm light is uniformly applied by a spin coater. This glass plate 10 has a light source wavelength of 655
The phase difference film 13 having a phase difference of 164 nm, which is ¼ of nm, is superposed on the coated surface of the transparent adhesive 12,
It is pasted by passing it between the rubber rollers arranged opposite to each other with a predetermined pressing pressure, and irradiating with 350 nm ultraviolet light,
A resin-made transparent adhesive 12 is cured to cure a retardation film 13
Glue.

Thereafter, the glass plate 10 with the retardation film 13 is cut so that the stress direction P of the retardation film 13 is at an angle of 45 ° with respect to the side 14a, so that one side is 3.4 mm. Square retardation film 1
The window glass 14 with 3 is manufactured.

Next, as shown in FIG. 5, a cap body 11 having a nickel-plated surface, which is produced by press-molding a thin Kovar metal plate, is provided with a flange portion 11.
It is installed so that d is on the upper side, and is sensitive to light with a wavelength of about 350 nm inside the top plate portion 11b, and about 2
An adhesive 15 made of a UV curable resin having a high viscosity of 0000 mPas is applied with a dispenser. A rectangular window plate glass 14 having a side of 3.4 mm is placed thereon with the retardation film 13 facing upward, and ultraviolet rays U of about 350 nm are irradiated from the side of the window plate glass 14 to cure and bond the adhesive 15. To do.

The semiconductor laser cap having a phase plate manufactured in this manner is then resistance-welded with the substantially rectangular stem to which the semiconductor laser chip is bonded and one side of the substantially square of the cap body 11 aligned. It is welded. At this time, if the electric field oscillating surface of the linearly polarized laser light emitted from the semiconductor laser chip is assembled so as to be parallel to the side of the substantially quadrangular stem, the assembled semiconductor laser is a linearly polarized light emitted from the semiconductor chip. Since the electric field vibration surface of the laser light and the stress direction P of the retardation film 13 are at an angle of 45 °, and the retardation film 13 has a retardation of λ / 4 with respect to the light source wavelength λ, The linearly polarized laser light emitted from the semiconductor laser chip is converted into circularly polarized laser light by the window glass 14 with the retardation film 13 and emitted from the window hole 11a of the semiconductor laser cap.

In the above embodiment, the cap body 11
Although the glass plate 10 is adhered to the side, the functional film does not change even if the retardation film 13 is adhered to the cap body 11 side.

In the above embodiment, the stress direction P of the retardation film 13 is 45 with respect to the side 14a of the quadrangle.
Although attached to the window glass 14 so as to have an angle of °, the stress direction P of the retardation film 13 is parallel to the side 14a of the quadrangle due to the positional relationship with the semiconductor laser chip bonded to the stem. It is also possible to attach at another angle.

Further, in the above embodiment, the cap main body 11 is manufactured with a rectangular cross section, but it can be manufactured with a round or rectangular cross section. It is easier to judge the stress direction of the retardation film 13 from the shape when the cross-section has a quadrangle, but a cross-section that is generally popular by devising such that the stress direction of the retardation film 13 can be distinguished by marking or the like. A round shape can also be manufactured. If necessary, the window glass 14
An antireflection film matched to the wavelength of the light source may be formed on the outer surface of the glass plate 10 or the outer surface of the retardation film 13.

Next, another example of the semiconductor laser cap according to the present invention will be shown.

FIG. 6 is an explanatory view of the window glass 20 of the semiconductor laser cap according to the present invention, in which 21 is a window glass.
Is a glass plate, 22 is a transparent adhesive made of UV curable resin,
Reference numeral 23 denotes a retardation layer, and 24 and 25 denote two types of retardation films having optical anisotropy which constitute the retardation layer 23.

The window glass 20 has a length of 5 mm, a width of 5 mm, and a thickness of 0.4 mm, as shown in FIG.
A glass plate 21 having a surface roughness Ra value of 0.4 nm of a and 21b and one light-transmissive surface 21a of the glass plate 21 has U
A retardation film 24 attached with a transparent adhesive 22 made of a V-curing resin and having a phase difference of 164 nm, which is ¼ of a light source wavelength of 655 nm, and a light source wavelength of 655 nm of 1
R of the surface roughness of the outer light-transmitting surface 23a, which is provided with the retardation film 25 having a retardation of 328 nm of ½.
The retardation layer 23 having an optical anisotropy having an a value of 1.4 nm and a thickness of 80 to 110 μm is provided. The retardation plate of the present invention uses the retardation layer 23 as the light source wavelength λ of 655n.
1 of λa / 4 for λa of m and λb of 785 nm
It has a phase difference of 64 nm and a phase difference of 196 nm of λb / 4.

In the window glass 20 having the above-mentioned structure, the rms value of the transmitted wavefront aberration is 9.8 nm (the light source wavelength λ is 655).
In nm, the rms value is 0.015λ, which is excellent.

The glass plate 21 of the retardation plate of the present invention is, for example, a light source wavelength 65 of a DVD device for a sample having a thickness of 1 mm.
It is made of borosilicate glass having a light transmittance of 5 nm of 91% or more.

The transparent adhesive 22 has, for example, a viscosity of 100 mPas which is sensitive to light having a wavelength of about 350 nm before curing.
Made of UV curable resin with low viscosity of ~ 4000 mPas,
The cured product has a refractive index of 1.50 to 1.53 and a thickness of 1 mm, and has a light transmittance of 98% or more at a wavelength of 655 nm.

The retardation films 24 and 25 are, for example, J
It has optical anisotropy such that it can be circularly polarized light in which the plane of polarization of the transmitted laser light such as "ARTON FILM" manufactured by SR Co., Ltd. is rotated by 45 degrees, or linearly polarized light is rotated by 90 degrees.

Next, an example of manufacturing the semiconductor laser cap of the present invention used in an optical system for an optical pickup of a DVD device will be described.

In advance, as the light source wavelength λ, λa of 655 nm
And the retardation film 24 having an arbitrary retardation is prepared by calculating a retardation for λb of 785 nm, and the wavelength dispersion of the retardation possessed by each retardation film is measured. I'll do it. Then, in consideration of the characteristics of wavelength dispersion, the bonding angle between the retardation films 24 and 25, the angle between the retardation film 24 and the polarization axis, 6
The above-mentioned combination is obtained in which the required phase difference is obtained for the light source wavelength in the range of 55 nm to 785 nm.

Next, the Ra value of the surface roughness of the transparent surface is 0.
Viscosity sensitive to light having a wavelength of about 350 nm has a viscosity of 100 mPas to 4000 mPa on the transparent surface of a large glass plate having a thickness of 4 nm.
s and a transparent adhesive 22 made of a low viscosity UV curable resin are applied using a spin coater or the like.

Next, as shown in FIG. 7 (A), 3 which is half of λa of 655 nm which is the light source wavelength of the DVD device.
A 90 μm ± 15 μm-thick retardation film 25 having a retardation of 28 nm is overlaid on a translucent surface of a large plate glass coated with a transparent adhesive 22 made of a UV curable resin, and rubbers arranged to face each other with a predetermined pressing force. Laminate them by passing them between rollers. At that time, when the glass plate 21 is cut out from the large glass plate in advance, the glass plate 21 and the retardation film 25 are laminated so that the angle formed with the stretching direction (delay axis direction) of the retardation film 25 is 76 °. This is preferable because waste can be minimized. After that, by irradiating the large plate glass to which the retardation film 25 is bonded with UV light to cure the resin adhesive layer having a thickness of 1 μm or more,
It becomes a large glass plate with a retardation film 25. further,
The stretching direction of the retardation film 14 having a thickness of 90 ± 15 μm having a retardation of 164 nm, which is ¼ of λa of the wavelength of 655 nm, becomes 58 ° counterclockwise with respect to the stretching direction of the retardation film 25. , Is superposed on the translucent surface of the large glass plate with the retardation film 25 on which the transparent adhesive 2 made of UV curable resin is applied on the film surface side, and is passed between the rubber rollers arranged facing each other with a predetermined pressing force. Stick together by doing.

After that, the large glass plate to which the retardation films 24 and 25 are bonded is irradiated with UV light to cure the resin adhesive layer having a thickness of 5 μm or more, as shown in FIG.
The large plate glass 26 with the retardation layer 23 as shown in FIG.

Next, as shown in FIG. 7B, the large glass plate 26 with the retardation layer 23 is diced to obtain the window glass 20 of a predetermined size. When the window glass 20 is a quadrangle, the angle formed by the cutting line 26a and the stretching direction of the retardation film 25 during stretching is counterclockwise.
Precisely dicing to be °. When using a commercially available dicing cutting device, a linear portion 28a is provided on a ring-shaped metal jig 28 on which the adhesive sheet 27 is stretched, and the linear portion 28a and the stretching direction of the retardation film 25 (delay axis). The large plate glass 26 is fixed to the dicing cutting device so that the angle formed by the (direction) and the direction (direction) becomes 76 °. Then, the large glass plate 26 is diced in parallel with the straight line portion 28a of the metal jig 28 to obtain the window glass plate 2 having a predetermined size.
Get 0. By making the polarization direction of the light source parallel and incident on one side 20a that forms 76 ° counterclockwise with the stretching direction (delay axis direction) of the retardation film 25, λa of 655 nm and 785 nm of the light source wavelength λ λb
, And functions as the window glass 20 having a phase difference of λa / 4 and λb / 4.

Thereafter, the cap for the semiconductor laser of the present invention used in the optical system for the optical pickup of the DVD apparatus is manufactured in the same manner as in FIG. 5 described above.

As described above, the retardation films 24 and 25 having optical anisotropy are attached to the glass plate 21 to form the retardation layer 23.
With such a structure, it is possible to obtain the window glass 20 that not only maintains the flatness of the light-transmitting surface but also has improved thermal stability of optical characteristics and high-temperature strength.

Further, since the retardation films 24 and 25 having optical anisotropy are adhered to the surface of the large glass plate 26 to form the retardation layer 23, dicing is performed, so that the window glass 20 having a small deviation of the polarization axis is formed. It can be manufactured.

If necessary, a broad band antireflection film adapted to a plurality of light source wavelengths may be applied to the outer transparent surface 21b of the glass plate 21 or the outer transparent surface 23a of the retardation layer 23 shown in FIG. It is possible.

The Ra value of the surface roughness of the light-transmitting surface of the window glass of the semiconductor laser cap of the present invention is a stylus type surface roughness measuring instrument manufactured by Rank Taylor Hobson Co., Ltd. under the trade name "Taristep". It was measured by. Also, the rms value of the transmitted wavefront aberration is the Fizeau interferometer model W manufactured by WYKO.
With the YKO400, the transmitted wavefront aberration generated when the laser light having the wavelength of 632.8 nm was transmitted through the region of φ1.5 mm of the light transmitting surface of the window glass was measured. The viscosity of the transparent adhesive 2 made of a UV curable resin is 25 ° C. with a trade name “SOLIDOMETER” model MR-300 made by Rheology Co., Ltd.
It was measured by a rotational viscometer method using a shear rate of 0.56 s ⁻¹ .

[0055]

According to the semiconductor laser cap of the present invention, elliptically polarized laser light (including circularly polarized light) can be used without inserting a separate optical element such as a wave plate into the optical system. Since the optical system can be downsized and the number of parts can be reduced, the optical system can be easily designed and the assembling cost can be reduced.

In the semiconductor laser cap of the present invention, since the window glass has the above-mentioned structure, it is possible to provide a predetermined phase difference with respect to a predetermined light source wavelength range, and an optical disk device having a plurality of light sources and a video. It is possible to significantly reduce the number of parts and simplify the optical system for an optical system such as a low-pass filter of a camera device.

Further, in the cap for semiconductor laser of the present invention, by changing the retardation film having optical anisotropy, a high-quality retardation plate matched to an arbitrary light source wavelength can be easily manufactured.

Further, in the cap for semiconductor laser of the present invention, the window glass has a structure in which a retardation film and a glass plate are bonded together with a transparent adhesive, so that the thermal stability of optical characteristics and the thermal stability of optical properties are improved as compared with the conventional one. A retardation plate having improved high temperature strength and excellent transmission wavefront aberration can be obtained, and can be manufactured more efficiently than conventional ones.

According to the semiconductor laser cap of the present invention, the window glass is substantially rectangular and the window glass is adhered to the window hole of the cap body having the substantially square top plate. Since it has a predetermined optical anisotropy with respect to one side of the substantially quadrangular shape, it is possible to efficiently manufacture a semiconductor laser that emits elliptically polarized laser light, particularly circularly polarized laser light. It plays.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of laser light that passes through a retardation film.

FIG. 2 is an explanatory diagram of laser light that passes through a retardation layer.

FIG. 3 is an explanatory view of a semiconductor laser cap with a retardation film of the present invention.

FIG. 4 is an explanatory view of a window glass with a retardation film, in which (A) is a sectional view and (B) is a plan view.

5A and 5B are explanatory views of a method of assembling the semiconductor laser cap of the present invention, where FIG. 5A is an explanatory view of applying a resin adhesive to the inside of the top plate portion of the cap body, and FIG. Explanatory drawing which mounts the window glass with a phase difference film on a top plate part, (C) is explanatory drawing which irradiates an ultraviolet-ray and hardens an adhesive agent and adheres a window glass to a cap main body.

FIG. 6 is an explanatory view of a window glass with a retardation layer which constitutes another semiconductor laser cap of the present invention.

FIG. 7 is an explanatory view showing a method for producing a window glass constituting a cap for another semiconductor laser of the present invention,
(A) is an explanatory view in which a retardation film is attached to a glass plate to form a retardation layer, and (B) is an illustration for obtaining a window glass from a large glass with a retardation layer.

FIG. 8 is an explanatory view of a conventional semiconductor laser cap.

[Explanation of symbols]

1, 11 Cap body 1a, 11a windows 1b, 11b Top plate part 1c, 11c tubular part 1d, 11d Flange part 2, 14, 20 Window glass 3 Low melting point glass 4 wavelength plate 10, 21 glass plate 12,22 Transparent adhesive 13, 24, 25 Retardation film 14a side 15 Adhesive 23 Phase difference layer 26 large glass 27 Adhesive sheet 28 Metal jig P stress direction U UV

Claims (6)

[Claims] 1. A cap body made of metal, in which a window for light transmission is formed in a top plate, and made of resin having a predetermined phase difference with respect to a light source wavelength λ due to optical anisotropy on a light transmitting surface. The retardation film comprises a window glass attached via a transparent resin adhesive, and the window glass is adhered to the window hole of the cap body via a resin adhesive. Caps for semiconductor lasers. 2. The cap for a semiconductor laser according to claim 1, wherein the retardation film attached to the window glass has a retardation of approximately λ / 4 with respect to the light source wavelength λ. 3. The retardation film attached to the window glass forms a retardation layer having a retardation of approximately λ / 4 with respect to a predetermined range of the light source wavelength λ. The semiconductor laser cap described in. 4. The window glass has a surface roughness Ra of a light transmitting surface.
4. The semiconductor laser according to claim 1, wherein the value of the retardation film is 0.5 nm or less, and the Ra value of the surface roughness of the outer transparent surface of the retardation film is 1.5 nm or less. For cap. 5. The rms value of the wavefront aberration generated when a laser beam passes through a φ1.5 mm region of a window glass is 13
The semiconductor laser cap according to any one of claims 1 to 4, wherein the cap is less than or equal to nm. 6. The window plate glass has a substantially quadrangular shape, and the window plate glass is adhered to a window hole of a cap body having a substantially quadrangular top plate portion. The semiconductor laser cap described in.