JPH1075015A - Semiconductor laser device, optical information recording/reproducing device using it, optical displacement gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide laser light of wavelength which is shorter than that of the fundamental wave by providing a semiconductor laser chip which outputs laser light of specified wavelength and non-linear optical crystal which can generate the second harmonic of the fundamental wave of the semiconductor laser. SOLUTION: As a semiconductor laser which emits fundamental wave (wavelength:λ), red visible light laser (λ:600nm-700nm), infrared light laser (750nm-), etc., is used. A non-linear optical crystal 4 which can generate second harmonic (wavelength:λ/2) of fundamental wave (wavelength:λ), outputted from a semiconductor laser chip 2 is used as a cover glass 1 of a semiconductor laser package 3. Since a part of the semiconductor laser package 3 is thus the non-linear optical crystal 4, the non-linear optical crystal 4 is not required to be set at other position, so the laser light of wavelength λ/2 is obtained without making the configuration of the entire device larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device,
And an optical information recording / reproducing apparatus and an optical displacement meter using the same.

[0002]

2. Description of the Related Art A semiconductor laser (LD) is used as a light emitting element for emitting a laser beam for recording and reproducing information in an optical information recording and reproducing apparatus such as an optical disk.

[0003] By the way, the density has been increasing to record more information on the optical disc. In this case, the pit width needs to be reduced with the miniaturization of the track pitch. The spot size to be focused must be smaller than before.

In general, a spot size r has a wavelength (λ) and
R = k · λ as a function of the numerical aperture (NA) of the objective lens
/ NA (k is a constant). Here, since the numerical aperture (NA) of the objective lens has a limit (determined by the aperture and the working distance), it is necessary to reduce the wavelength (λ) in order to reduce the spot size r.

Therefore, the SD (Super Density Disk, track pitch = 0.
In an optical disc device (optical information recording / reproducing device) for recording information at a higher density than 74 μm), a signal cannot be reproduced with a reproducing beam having a spot size focused by the current LD (λ: ６670 nm). . For this reason, the development of a blue light semiconductor laser (λ: up to 410 nm) using GaN (gallium nitride) or the like has been advanced.

[0006]

However, the above-mentioned blue light semiconductor laser device is not practical in terms of wavelength stability at room temperature, life, power of output light, etc., and the problem of pulse oscillation still remains. ing.

The semiconductor laser device of the present invention has been made in view of such a problem, and its purpose is to use a conventional semiconductor laser such as a red visible light laser or an infrared light laser. Another object of the present invention is to provide a semiconductor laser device capable of obtaining laser light having a wavelength smaller than the fundamental wave without increasing the configuration of the device.

[0008]

In order to achieve the above object, a semiconductor laser device according to a first aspect of the present invention has a semiconductor laser chip for outputting a laser beam having a predetermined wavelength, and houses the semiconductor laser chip. A semiconductor laser package, and a second harmonic (wavelength: λ / 2) of a fundamental wave (wavelength: λ) of a semiconductor laser provided either as a part of the semiconductor laser package or provided inside the semiconductor laser package. And a non-linear optical crystal capable of generating a).

Further, in the semiconductor laser device according to a second aspect of the present invention, in the semiconductor laser device according to the first aspect, the nonlinear optical crystal is used for extracting output light of the semiconductor laser to outside the semiconductor laser package. Used as cover glass.

The semiconductor laser device according to a third invention is the semiconductor laser device according to the second invention, wherein an optical lens is disposed in contact with a surface of the cover glass facing the semiconductor laser chip. Have been.

A semiconductor laser device according to a fourth invention is the semiconductor laser device according to the second invention, wherein the cover glass is made of an optical lens, and the optical lens is a laser light output of the semiconductor laser chip. It is arranged in contact with the part.

According to a fifth aspect of the present invention, there is provided a semiconductor laser device according to the first aspect, wherein one surface of the nonlinear optical crystal is disposed in contact with a laser light output section of the semiconductor chip. I have.

According to a sixth aspect of the present invention, in the semiconductor laser device according to the fifth aspect, one surface of the nonlinear optical crystal is disposed in contact with a laser light output section of the semiconductor chip. In addition, the other surface of the nonlinear optical crystal is arranged in contact with a cover glass for extracting output light of the semiconductor laser to the outside of the semiconductor laser package.

Further, an optical information recording / reproducing apparatus according to a seventh aspect uses the semiconductor laser device according to any one of the first to sixth aspects. Further, an optical displacement meter according to an eighth aspect uses the semiconductor laser device according to any one of the first to sixth aspects.

That is, in the semiconductor laser device of the present invention, a semiconductor laser chip for outputting a laser beam of a predetermined wavelength is housed in a semiconductor laser package, and a second harmonic of a fundamental wave (wavelength: λ) of the semiconductor laser. A nonlinear optical crystal capable of generating a wave (wavelength: λ / 2) is provided as a part of the semiconductor laser package or provided inside the semiconductor laser package.

For example, the nonlinear optical crystal is used as a cover glass for extracting the output light of the semiconductor laser to the outside of the semiconductor laser package, or the cover glass is formed of an optical lens, and This optical lens is arranged in contact with the laser light output section of the semiconductor laser chip. Further, one surface of the nonlinear optical crystal is disposed in contact with a laser light output portion of the semiconductor chip, or the other surface of the nonlinear optical crystal further outputs the output light of the semiconductor laser to the semiconductor laser. It is arranged in contact with a cover glass to be taken out of the package. The above-described semiconductor laser device is used for an optical information recording / reproducing device or an optical displacement meter.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of an embodiment of the present invention will be described. In this embodiment, 1) without using a semiconductor laser (λ: ∼410 nm) using GaN (gallium nitride) or the like, which is currently in development, as a semiconductor laser that emits a fundamental wave (wavelength: λ). A red visible light laser (600 nm to 700 nm) or an infrared light laser (750 nm or more) currently available in the market is used. 2) Crystals capable of generating the second harmonic (wavelength: λ / 2) of the fundamental wave (wavelength: λ) of the semiconductor laser include BBO and K
A nonlinear optical crystal such as DP or KTP is used. 3) The nonlinear optical crystal is used as a cover glass as a part of a semiconductor laser package, or is arranged inside the semiconductor laser package, for example, in contact with a laser light output section of a semiconductor chip.

By using the above configuration,
Using a conventional visible or infrared semiconductor laser and without increasing the configuration of the device, continuous oscillation light having a half wavelength λ / 2 of the fundamental wavelength λ, for example, blue laser light can be generated. . Therefore, SD (Super Density
It can be used as a light source of an optical disk (optical information recording / reproducing device) having a higher density than that of the optical disk, or as an optical displacement meter.

FIG. 1 is a diagram showing a configuration of a semiconductor laser device according to a first embodiment of the present invention. In the first embodiment, the fundamental wave (wavelength: λ) output from the semiconductor laser chip 2
Characterized in that a nonlinear optical crystal 4 capable of generating the second harmonic (wavelength: λ / 2) is used as the cover glass 1 of the semiconductor laser package 3. Here, BBO (beta barium borate) or the like is used as the nonlinear optical crystal 4.

According to such a configuration, since a part of the semiconductor laser package 3 is formed as the nonlinear optical crystal 4, it is not necessary to provide the nonlinear optical crystal 4 at another position, thereby increasing the configuration of the entire device. Without this, a laser beam having a wavelength of λ / 2 can be obtained.

FIG. 2 is a diagram showing a configuration of a semiconductor laser device according to a second embodiment of the present invention. In this embodiment,
In addition to the configuration of FIG. 1, a collimating lens 5 is adhered to the cover glass 1 with an adhesive. Therefore, the laser light from the semiconductor laser chip 2 is converted into parallel light by the collimating lens 5 and then passes through the cover glass 1 (nonlinear optical crystal 4) to obtain a laser light having a wavelength of λ / 2.

According to such a configuration, since the collimating lens 5 is disposed inside the semiconductor laser package 3, parallel laser light having a wavelength of λ / 2 can be obtained without increasing the configuration of the entire device. it can.

FIG. 3 is a diagram showing a configuration of a semiconductor laser device according to a third embodiment of the present invention. In this embodiment,
The cover glass 1 ′ is constituted by the nonlinear optical crystal 4, and the cover glass 1 ′ is further used as a collimating lens 5 ′. The collimating lens 5 ′ is a laser light output of the semiconductor laser chip 2. It is arranged in contact with the part.

According to such a configuration, the laser beam from the semiconductor laser chip 2 is incident on the collimating lens 5 'forming the cover glass 1' in a substantially focused state, and
Since a parallel laser beam having a wavelength of / 2 is output, a parallel laser beam having a wavelength of λ / 2 can be obtained without increasing the configuration of the entire device, and the output laser beam from the semiconductor laser chip 2 can be obtained. Power efficiency can be increased. Also,
Unlike the configuration of FIG. 2, it is not necessary to bond the collimating lens to the cover glass.

FIG. 4 is a diagram showing a configuration of a semiconductor laser device according to a fourth embodiment of the present invention. In this embodiment,
The fundamental wave (wavelength:
A nonlinear optical crystal 4 capable of generating the second harmonic (wavelength: λ / 2) of λ) is bonded to a laser light output portion of the semiconductor laser chip 2 in the semiconductor laser package 3 with an adhesive. . Here, BBO (beta barium borate) or the like is used as the nonlinear optical crystal 4.

According to such a configuration, since the laser light from the semiconductor laser chip 2 is incident on the nonlinear optical crystal 4 in a substantially focused state, the power efficiency of the output light from the semiconductor laser chip 2 can be increased. it can.

FIG. 5 is a diagram showing a configuration of a semiconductor laser device according to a fifth embodiment of the present invention. In this embodiment,
The fundamental wave (wavelength:
One surface of the non-linear optical crystal 4 capable of generating the second harmonic (wavelength: λ / 2) of (λ) is placed in contact with the laser light output portion of the semiconductor laser chip 2 in the semiconductor laser package 3 and The other surface of the optical crystal 4, that is, the surface that is not in contact with the semiconductor laser chip 2 is arranged in contact with the cover glass 1.

According to such a configuration, a parallel laser beam having a wavelength of λ / 2 can be obtained without increasing the overall configuration of the device, and the power efficiency of the output light from the semiconductor laser chip 2 can be reduced. Can increase. FIG.
It is not necessary to bond the non-linear optical crystal to the semiconductor laser chip as in the configuration described above.

In the first, second, fourth, and fifth embodiments, the nonlinear optical crystal 4 has a flat plate shape. However, the present invention is not limited to this. As long as it has a curvature, a shape as shown in FIG. 6 can be used. As described above, KTP (barium phosphotitanate) or the like can be used as the nonlinear optical crystal 4 in addition to BBO.

[0030]

According to the present invention, laser light having a wavelength smaller than the fundamental wave can be obtained using a conventional semiconductor laser such as a red visible light laser or an infrared light laser without increasing the configuration of the apparatus. Can be obtained. In addition, this makes it possible to use the optical disk as a light source for a high-density optical disk.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 6 is a diagram showing another shape of the nonlinear optical crystal.

[Explanation of symbols]

1, 1 ': cover glass, 2: semiconductor laser chip, 3
... semiconductor laser package, 4 ... nonlinear optical crystal, 5,
5 ': Collimating lens.

Claims (8)

[Claims] A semiconductor laser chip for outputting a laser beam of a predetermined wavelength; a semiconductor laser package for accommodating the semiconductor laser chip; and a semiconductor laser package provided as a part of the semiconductor laser package. And a non-linear optical crystal provided inside and capable of generating a second harmonic (wavelength: λ / 2) of a fundamental wave (wavelength: λ) of the semiconductor laser. 2. The semiconductor laser device according to claim 1, wherein said nonlinear optical crystal is used as a cover glass for extracting output light of said semiconductor laser to outside of said semiconductor laser package. 3. The semiconductor laser device according to claim 2, wherein an optical lens is disposed in contact with a surface of said cover glass facing said semiconductor laser chip. 4. The semiconductor laser device according to claim 2, wherein said cover glass is formed of an optical lens, and said optical lens is disposed in contact with a laser light output section of said semiconductor laser chip. . 5. The semiconductor laser device according to claim 1, wherein one surface of said nonlinear optical crystal is arranged in contact with a laser light output section of said semiconductor chip. 6. One surface of the nonlinear optical crystal is disposed in contact with a laser light output portion of the semiconductor chip, and the other surface of the nonlinear optical crystal transmits output light of the semiconductor laser to the semiconductor laser. 6. The semiconductor laser device according to claim 5, wherein the semiconductor laser device is arranged in contact with a cover glass for taking out the package. 7. An optical information recording / reproducing apparatus using the semiconductor laser device according to claim 1. Description: 8. An optical displacement meter using the semiconductor laser device according to claim 1. Description: