JP2013069371A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device suitable as a laser device to be contained in an optical pickup apparatus that performs read operation of a signal recorded in an optical disk.SOLUTION: A semiconductor laser device is assembled by welding and fixing a cap 17, in which an aperture 18 for emitting a laser beam to the outside is sealed by a cover glass 19, to a stem 13 on which a laser chip 16 for creating a laser beam is mounted. The cover glass 19 comprises a wavelength plate.

Description

  The present invention relates to a semiconductor laser device incorporated in an optical pickup device that performs reading operation of a signal recorded on an optical disc and recording operation of a signal on an optical disc by laser light.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reading operation and signal recording operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is generally widespread. Recently, an optical disk with improved recording density, that is, an apparatus using a Blu-ray standard optical disk has been developed.

  As a laser beam for performing an operation for reading a signal recorded on a CD standard optical disk, an infrared light having a wavelength of 780 nm is used, and a laser beam for performing an operation for reading a signal recorded on a DVD standard optical disk. In this case, red light having a wavelength of 650 nm is used.

  For such CD standard and DVD standard optical disks, the laser light for performing the read operation of the signals recorded on the Blu-ray standard optical disk is a laser light having a short wavelength, for example, a blue-violet light having a wavelength of 405 nm. It is used.

  In an optical pickup device, a laser diode, that is, a semiconductor laser device is generally employed as means for generating laser light (see Patent Document 1).

JP 2006-216817A

  FIG. 4 is an optical configuration diagram of an optical pickup device configured to read a signal recorded on a signal recording layer L provided in an optical disc D defined by the Blu-ray standard. The optical pickup device will be described with reference to FIG.

  In FIG. 4, 1 is a laser diode that emits laser light, for example, blue-violet light having a wavelength of 405 nm, and 2 is a half-wave plate on which the laser light emitted from the laser diode 1 is incident. For example, the laser beam is converted into linearly polarized light in the S direction. Reference numeral 3 denotes a diffraction grating on which the laser light transmitted through the half-wave plate 2 is incident, and separates the laser light into a main beam that is 0th order light, a + 1st order light, and two subbeams that are −1st order light. It works.

  Reference numeral 4 denotes a polarization beam splitter on which the laser light transmitted through the half-wave plate 2 and the diffraction grating 3 is incident. The laser beam reflects most of the laser light converted into S-polarized light and is polarized in the P direction. A control film 4a that transmits light is provided. Reference numeral 5 denotes a monitor photodetector provided at a position where the laser beam transmitted through the control film 4a of the polarization beam splitter 4 in the laser beam emitted from the laser diode 1 is irradiated, and its detection output The monitor signal is used to control the output of the laser light emitted from the laser diode 1.

  Reference numeral 6 denotes a quarter wavelength plate provided at a position where the laser beam reflected by the control film 4a of the polarization beam splitter 4 is incident. The incident laser beam is changed from linearly polarized light to circularly polarized light. On the other hand, it also functions to convert circularly polarized light into linearly polarized light. Reference numeral 7 denotes a collimating lens for converting the incident laser light into parallel light as the laser light transmitted through the quarter-wave plate 6 is incident thereon, and is displaced in the optical axis direction by the aberration correction motor 8. It is configured. That is, the spherical aberration generated based on the thickness of the protective layer provided between the signal recording layer L of the optical disc D and the disc surface can be corrected by the displacement operation of the collimating lens 7 in the optical axis direction. It is configured as follows.

  Reference numeral 9 denotes a rising mirror provided at a position where the laser beam transmitted through the collimating lens 7 is incident. The rising mirror 9 changes the emission direction of the incident laser beam by 90 degrees, and the laser beam is recorded on the optical disc D. The light is reflected in the direction of the objective lens 10 provided to be condensed on the layer L.

  In such a configuration, the laser light emitted from the laser diode 1 passes through the half-wave plate 2, the diffraction grating 3, the polarization beam splitter 4, the quarter-wave plate 6, the collimator lens 7, and the rising mirror 9. After being incident on the objective lens 10, the signal recording layer L of the optical disc D is irradiated as a laser spot by the focusing operation of the objective lens 10, but the laser light irradiated on the signal recording layer L is used as return light. The light is reflected toward the objective lens 10 side.

  The return light reflected from the signal recording layer L of the optical disc D enters the control film 4 a of the polarization beam splitter 4 through the objective lens 10, the raising mirror 9, the collimator lens 7, and the quarter wavelength plate 6. Thus, the return light incident on the control film 4 a of the polarization beam splitter 4 is changed to linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 6. Therefore, such return light is not reflected by the control film 4a of the polarizing beam splitter 4, but passes through the control film 4a as control laser light.

  Reference numeral 11 denotes a sensor lens into which the control laser light transmitted through the control film 4a of the polarizing beam splitter 4 is incident. Astigmatism is added to the control laser light in the light receiving portion provided in the photodetector 12 called PDIC. The effect of irradiating with the addition of. As is well known, the photodetector 12 is provided with a four-divided sensor or the like, and a signal generation operation associated with a read operation of a signal recorded on the signal recording layer L of the optical disc D by a main beam irradiation operation; A focus error signal generating operation for performing the focus control operation by the astigmatism method and a tracking error signal generating operation for performing the tracking control operation by the irradiation operation of the two sub beams are performed.

  As described above, the optical system of the optical pickup device is configured, and the half-wave plate 2 and the quarter-wave plate 6 are bonded and fixed to a base called a housing constituting the optical pickup device by an ultraviolet curable adhesive. It is configured to be.

  When a half-wave plate or the like is bonded and fixed to the housing, it is necessary to perform a positioning operation to a fixing position formed in the housing of the wave plate, an adhesive application operation, an ultraviolet irradiation operation, or the like. There is a problem that the number of work processes increases. In addition, since the wavelength plate is inserted and disposed in the optical path of the laser beam, there is a problem that the opportunity for dust such as dust to adhere to the surface of the wavelength plate increases.

  The present invention seeks to provide a semiconductor laser device capable of solving such problems.

  The present invention relates to a semiconductor that is assembled by welding and fixing a cap configured such that an opening for emitting laser light to the outside is sealed by a cover glass to a stem on which a laser chip for generating laser light is mounted. In the laser apparatus, the cover glass is constituted by a wave plate.

  In the semiconductor laser device of the present invention, the cover glass that seals the opening of the cap that is welded and fixed to the stem on which the laser chip is mounted is configured by the wavelength plate. There is no need to bond and fix the wave plate to a certain housing. Therefore, since the number of assembly steps of the optical pickup device can be reduced, the present invention has an effect that the productivity of the optical pickup device can be improved.

  Further, according to the present invention, since the number of optical components constituting the optical system of the optical pickup device can be reduced, not only the manufacturing cost of the optical pickup device can be reduced but also the reliability can be improved.

1 is a side sectional view of a semiconductor laser device according to the present invention. 1 is a perspective view of a semiconductor laser device according to the present invention. 1 is an exploded perspective view of a semiconductor laser device according to the present invention. It is an optical block diagram of the optical pick-up apparatus which concerns on this invention.

  Provided is a semiconductor laser device incorporated in an optical pickup device that performs an operation of reading a signal recorded on a signal recording layer provided in an optical disc.

  FIG. 2 is a perspective view showing a semiconductor laser device according to the present invention, which is generally called a can type. FIG. 3 is an exploded perspective view of the can type semiconductor laser device shown in FIG.

  In the figure, reference numeral 13 denotes a base called a stem, which is made of a metal such as iron or copper and to which a lead terminal 14 for supplying power is fixed. Reference numeral 15 denotes a sub-base fixed to the stem 13, and a laser chip 16 that emits laser light is fixed thereto. In such a configuration, both are connected by a lead wire or the like so that a drive signal is supplied to the laser chip 16 via the lead terminal 14.

  Reference numeral 17 denotes a cylindrical cap fixed to the stem 13 by welding, and a circular opening 18 is formed on the upper surface. That is, the opening 18 is provided for emitting laser light emitted from the laser chip 16.

  Reference numeral 19 denotes a cover glass that seals the opening 18 formed in the cap 17, and is bonded and fixed to the inside of the cap 17 by a low-melting glass 20 as shown in a sectional view in FIG. 1. The opening 18 formed in the cap 17 can be sealed by bonding and fixing the cover glass 19 to the inner surface of the cap 17 with a low melting point glass 20.

  2 is assembled by welding and fixing the cap 17 whose opening 18 is sealed by the cover glass 19 to the stem 13. In the can type semiconductor laser device shown in FIG. In addition, the welding fixing operation of the cap 17 to the stem 13 is performed in a state where the space inside the cap 17 is filled with an inert gas.

  By performing the assembly operation described above, a can-type semiconductor laser device as shown in FIG. 2 is assembled and manufactured. In this configuration, the present invention is characterized in that the cover glass 19 for sealing the opening 18 formed in the cap 17 is configured by a half-wave plate.

  If the cover glass 19 provided in the can-type semiconductor laser device is configured with a half-wave plate, the half-wave plate 2 can be eliminated from the optical configuration diagram shown in FIG. That is, since it is not necessary to perform the adhesive fixing work of the half-wave plate 2 to the housing, the assembly work of the optical pickup device can be easily performed. In addition, since the half-wave plate 2 can be eliminated, the chance that dust such as dust adheres to the half-wave plate 2 can be reduced, and as a result, the characteristics of the optical pickup device can be improved. .

  Further, a slight shift of the mounting angle of the half-wave plate, for example, a shift of several degrees does not have a great influence on the optical characteristics, so that it is easy to fix the cover glass 19 to the inside of the cap 18. Can be done.

  In this embodiment, the cover glass 19 is composed of a half-wave plate, but can be composed of a quarter-wave plate.

DESCRIPTION OF SYMBOLS 1 Laser diode 2 1/2 wavelength plate 13 Stem 15 Sub base 16 Laser chip 17 Cap 18 Opening part 19 Cover glass

Claims (3)

It is a semiconductor laser device that is assembled by welding and fixing a cap configured so that an opening for emitting laser light to the outside is sealed by a cover glass to a stem on which a laser chip for generating laser light is mounted A semiconductor laser device, wherein the cover glass is composed of a wave plate. 2. The semiconductor laser device according to claim 1, wherein the wave plate is a half wave plate. 2. The semiconductor laser device according to claim 1, wherein the wave plate is a quarter wave plate.

Images