JP2006059471A - Laser emitting apparatus and optical head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify constitution of an optical head, to reduce loss of light in the optical head, and to generate laser beams of different beam diameters. <P>SOLUTION: A three wavelength laser module 10 is provided with a laser emitting part 31 outputting laser beams of three wavelength of 785 nm (infrared), 660 nm (read color), 405 nm (blue-violet color). The laser emitting part 31 has a heat sink 41, a blue-violet color semiconductor laser element 42 adhered on the heat sink 41, a red color semiconductor laser element 43 adhered on the blue-violet color semiconductor laser element 42, an infrared semiconductor laser element 44, and a magnification correcting lens 45. The blue-violet color laser beam, the read color laser beam, and the infrared laser beam are emitted in the same direction. The light emitting point of the blue-violet color semiconductor laser element 42 is positioned at a more rear side than light emitting points of the read color and infrared semiconductor laser elements 43, 44, and the magnification correcting lens 45 of plus power is provided between them. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser emitting device that incorporates a plurality of types of semiconductor lasers and emits laser light having a plurality of wavelengths, and an optical head using the laser emitting device.

  Conventionally, a compact disc (hereinafter referred to as CD) using an infrared semiconductor laser with a wavelength of 785 nm as recording / reproducing light, and a digital video disc (hereinafter referred to as DVD) using a red semiconductor laser with a wavelength of 660 nm as recording / reproducing light. .) In recent years, the capacity of optical disks has been increased, and an optical disk called a Blu-ray disk (Blu-ray disk: hereinafter referred to as BD) using a blue-violet semiconductor laser having a wavelength of 405 nm as recording / reproducing light has been proposed.

  In addition, the present applicant has proposed a three-wavelength laser module in accordance with the development of an optical head for the third generation of CD, DVD, and BD (see Non-Patent Document 1). The three-wavelength laser module is a laser light emitting module that can emit laser light corresponding to three generations of CD, DVD, and BD from one exit window. That is, a device in which each element of an infrared semiconductor laser with a wavelength of 785 nm, a semiconductor laser with a wavelength of 660 nm, and a semiconductor laser with a wavelength of 405 nm is housed in one package.

  FIG. 5 shows a configuration example of a three-generation optical head using a three-wavelength laser module.

  As shown in FIG. 5, the optical head 100 includes a three-wavelength laser module 101, a collimator lens 102, a polarization beam splitter 103, a magnification conversion mechanism 104, a quarter-wave plate 105, an objective lens 106, a collecting lens, and the like. An optical lens 107 and a photodetector 108 are provided.

  The three-wavelength laser module 101 emits an infrared laser beam having a wavelength for CD of 785 nm, a red laser beam having a wavelength for DVD of 660 nm, and a blue-violet laser beam having a wavelength for BD of 405 nm. Laser light emitted from the three-wavelength laser module 101 enters the collimator lens 102. Three wavelengths of laser light emitted from the three-wavelength laser module 101 to the collimator lens 102 are emitted in a state of diverging light (diverging light) from approximately one point. The collimator lens 102 makes incident light parallel light.

  The laser light that has passed through the collimator lens 102 enters the polarization beam splitter 103 as P-polarized light. The polarization beam splitter 103 transmits P-polarized light and reflects S-polarized light, so that light (P-polarized light) incident from the collimator lens 102 side is transmitted. The light transmitted through the polarization beam splitter 103 passes through the magnification conversion storage 104 and the quarter wavelength plate 105 and enters the objective lens 106.

  The objective lens 106 condenses the laser beam incident through the quarter-wave plate 105 and irradiates the optical disc D. The return light reflected from the optical disk D is incident on the objective lens 106.

  The return light that has passed through the objective lens 106 passes through the quarter-wave plate 105 and enters the polarization beam splitter 103. This time, it passes through the quarter-wave plate 105 twice and enters the polarization beam splitter 103 as S-polarized light, and is reflected by the polarization beam splitter 103.

  The return light reflected by the polarization beam splitter 103 passes through the condenser lens 107 and is irradiated on the photodetector 108.

  The photodetector 108 converts the irradiated light into an electrical signal and outputs it to a matrix amplifier or the like.

“Nikkei Electronics, June 7, 2004 issue No. 875”, Nikkei BP, issued June 7, 2004, p. 24-25

  By the way, the numerical aperture NA of the CD objective lens is 0.45, the numerical aperture of the DVD objective lens is 0.6, and the numerical aperture of the BD objective lens is 0 and 85. The objective lens 106 realizes these differences with a single lens. Therefore, the numerical aperture is set to 0.45 and 0.6 when the central portion of the lens is used, and the peripheral portion of the lens is used when the peripheral portion of the lens is used. The numerical aperture is configured to be 0.85.

  When such an objective lens 106 is used, it is necessary to adjust so that the beam diameter of the laser beam for CD and DVD is reduced and the beam diameter of the laser beam for BD is increased.

  The adjustment of the beam diameter can be easily performed by adjusting the optical path length from the laser light emitting device to the collimator. However, when the three-wavelength laser module 101 is used, the emission position is the same at all wavelengths and is difficult. Further, at the time of recording and reproduction of CD and DVD using only the central portion of the lens, it can be realized by providing a diaphragm that cuts most of the peripheral portion of the beam, but the loss becomes very large.

  In view of this, the present applicant has provided a magnification conversion mechanism 104 that enlarges the beam diameter (see Non-Patent Document 1). The magnification conversion mechanism is inserted during BD recording / reproduction, and is removed from the optical path during CD / DVD recording / reproduction. For this reason, the magnification of the optical system at the time of recording / reproducing BD becomes larger than the magnification at the time of recording / reproducing of CD and DVD. By providing such a magnification conversion mechanism 104, laser light can be irradiated without loss.

  However, it is still desirable that the laser beam can be irradiated without loss without providing the magnification conversion mechanism 104.

  The present invention is a laser emitting apparatus that incorporates a plurality of types of semiconductor lasers and emits laser light of a plurality of wavelengths, and can simplify the configuration of the optical head and reduce light loss in the optical head. It is an object of the present invention to provide a laser emitting device that can be reduced, and an optical head using such a laser emitting device.

A laser emitting apparatus according to the present invention emits a first laser beam having a wavelength λ ₁ provided on a main surface of a support base having a planar main surface and parallel to the main surface of the support base. A wavelength λ _{1 in the} same direction as the laser beam emitted from the first semiconductor laser element and parallel to the main surface of the support base provided on the first semiconductor laser element and the first semiconductor laser element A laser light emitting section having a second semiconductor laser element emitting a second laser light having a wavelength λ ₂ different from the above, and an enlarging or reducing optical element, and the first laser light and the second laser light are incident thereon An emission optical system for emitting these laser beams to the outside, and the emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser light. The above-mentioned enlargement or reduction optics Child, characterized in that the exit position is provided in the spaced area in the optical path of the semiconductor laser element located in the traveling direction behind the laser beam.

A laser emitting apparatus according to the present invention emits a first laser beam having a wavelength λ ₁ provided on a main surface of a support base having a planar main surface and parallel to the main surface of the support base. A wavelength λ _{1 in the} same direction as the laser beam emitted from the first semiconductor laser element and parallel to the main surface of the support base provided on the first semiconductor laser element and the first semiconductor laser element A second semiconductor laser element that emits a second laser beam having a longer wavelength λ ₂ , and is provided on the first semiconductor laser element in the same direction as the second laser beam, with a wavelength λ ₂ A laser light emitting unit having a third semiconductor laser element that emits a third laser beam having a long wavelength λ ₃ , and the first laser beam, the second laser beam, and the third laser beam are incident thereon. And a synthetic optical system that emits laser light to the outside The emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam, and the emission position of the second semiconductor laser element and the third semiconductor The emission position of the laser element is the same position in the traveling direction of the laser beam, and the enlargement or reduction optical element is in the optical path of the semiconductor laser element whose emission position is located behind the traveling direction of the laser beam. It is provided in the said separation | spacing part, It is characterized by the above-mentioned.

An optical head according to the present invention includes a laser emitting device that outputs laser light having a different wavelength from one exit window according to the type of the optical disc, and the laser emitting device in an optical head that emits laser light to an optical disc. The collimator lens that makes the laser beam output from the collimated beam parallel to the collimator lens and the numerical aperture of the central portion are low, the collimated laser beam that has passed through the collimator lens is incident, and the incident light is incident on the optical disc. The laser emitting device includes a support base having a planar main surface, and a first substrate having a wavelength λ ₁ provided on the main surface of the support base and parallel to the main surface. A first semiconductor laser element that emits one laser beam; and the first semiconductor laser that is provided on the first semiconductor laser element and is parallel to a main surface of the support base. Laser emitting unit is housed with the second semiconductor laser element for emitting a second laser beam emitted wavelength lambda ₂ of the laser beam in the same direction different from the wavelength lambda ₁ from the child, the enlargement or reduction optical element In addition, the emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam. The semiconductor laser device is provided in the separated portion in the optical path of the semiconductor laser element located on the rear side in the light traveling direction.

The optical head according to the present invention includes a laser emitting device that outputs laser beams of three different wavelengths from one exit window according to the type of the optical disc, and the laser that emits laser light to the optical disc. A collimator lens that collimates the laser beam output from the emitting device, and the numerical aperture of the central portion is low, the collimated laser beam that has passed through the collimator lens is incident, and the incident light is And an objective lens that irradiates an optical disk. The laser emitting device includes a support base having a planar main surface and a wavelength λ ₁ provided on the main surface of the support base and parallel to the main surface. A first semiconductor laser element that emits the first laser beam; and a first semiconductor laser element provided on the first semiconductor laser element and parallel to a main surface of the support base. A second semiconductor laser element for emitting a second laser beam of longer wavelength lambda ₂ than the wavelength lambda ₁ in a direction different from the laser light emitted from over laser device, provided on the first semiconductor laser element is the which is the laser emitting unit is housed with a third semiconductor laser device in a second same direction as the laser beam to emit a third laser beam of longer wavelength lambda ₃ than the wavelength lambda _2, the first semiconductor The emission position of the laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser light, and the emission position of the second semiconductor laser element and the emission position of the third semiconductor laser element. The position is the same position in the traveling direction of the laser beam, and the enlargement or reduction optical element is located in the separated portion in the optical path of the semiconductor laser element whose emission position is located behind the traveling direction of the laser beam. Provided And said that you are.

A laser emitting apparatus according to the present invention includes a first semiconductor laser element that emits a first laser beam and a second semiconductor laser element that emits a second laser beam having a wavelength λ ₂ in the same direction. The laser emitting unit is integrally formed with the light emitting unit, and the emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam. In addition, an enlargement or reduction optical element is provided in the above-mentioned separated portion in the optical path of the semiconductor laser element whose emission position is located behind the traveling direction of the laser light.

  Thus, in the laser emission device according to the present invention, two laser beams having different divergence angles are output from one emission window. Therefore, in the laser emitting apparatus according to the present invention, the beam diameters of the first laser light and the second laser light can be made different from each other with a simple configuration and no light loss.

An optical head according to the present invention includes a laser emitting device, a collimator lens that uses laser light output from the laser emitting device as parallel light, and an objective lens having a low numerical aperture at the center. The laser emitting device includes: a laser emitting unit having a first semiconductor laser element that emits a first laser beam; and a second semiconductor laser element that emits a second laser beam having a wavelength λ ₂ in the same direction; Are integrally formed, and the emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam. An enlarging or reducing optical element is provided in the above-mentioned separated portion in the optical path of the semiconductor laser element whose position is located behind the traveling direction of the laser beam.

  Thus, in the optical head according to the present invention, two laser beams having different divergence angles are output from one emission window from the laser emission device. Therefore, in the optical head according to the present invention, the beam diameters of the first laser beam and the second laser beam can be made different from each other with a simple configuration and no light loss.

  An optical head to which the present invention is applied will be described.

  FIG. 1 is a schematic configuration diagram of an optical head 1 to which the present invention is applied.

  The optical head 1 collects and irradiates a recording / reproducing laser beam onto the optical disc D, detects the reflected light, and converts it into an electrical signal.

  There are three types of optical disks D that use the optical head 1: CD, DVD, and BD. In other words, the optical head 1 emits laser light having three wavelengths: a laser beam having a wavelength of 785 nm for CD, a laser beam having a wavelength of 660 nm for DVD, and a laser beam having a wavelength of 405 nm for BD. While irradiating the optical disk D with laser light, the reflected light is detected.

  As shown in FIG. 1, the optical head 1 includes a three-wavelength laser module 10, a collimator lens 11, a polarizing beam splitter 12, a quarter-wave plate 13, an objective lens 14, a condenser lens 15, and a photodetector. 16.

  The three-wavelength laser module 10 includes an infrared semiconductor laser element for CD that emits infrared laser light having a wavelength of 785 nm, a red semiconductor laser element for DVD that emits red laser light having a wavelength of 660 nm, and a blue semiconductor laser element having a wavelength of 405 nm. A blue-violet semiconductor laser element for BD that emits violet laser light is built in the same package 20, and three-wavelength laser light emitted from these is emitted from one exit window 21 to the outside in the same direction. Exit. The three-wavelength laser module 10 emits one of these three wavelengths of laser light in accordance with external control. That is, control is performed so that laser light of any one wavelength is emitted depending on whether the optical disk D loaded is a CD, a DVD, or a BD.

  Light emitted from the three-wavelength laser module 10 enters the collimator lens 11. The collimator lens 11 turns incident light into parallel light fluxes.

Here, the laser beams of three wavelengths emitted from the three-wavelength laser module 10 are emitted to the outside from the same emission window 21 in a state of light (diverged light) diverging from substantially one point. The three-wavelength laser light passes through substantially the same optical axis and enters the collimator lens 11. However, among the three wavelengths of laser light, the spread angle of the divergent light of the laser beam for BD (wavelength 405 nm) is θ ₁ and the spread angle of the divergent light of the laser light for CD and DVD (wavelength 785 nm and 660 nm) When θ ₂ , θ ₁ > θ ₂ is satisfied. In other words, the divergence angle θ ₁ of the BD laser light is wider than the divergence angle θ ₂ of the laser light for CD and DVD.

Therefore, the laser beam L1 for BD which is a parallel light flux after passing through the collimator lens 11 and the beam diameter phi _1, CD, which is a parallel light flux after passing through the collimator lens 11, the laser beam L2 for DVD When compared with the beam diameter φ ₂ , φ ₁ > φ ₂ is satisfied. That, CD, than the beam diameter phi ₂ after having been converged into a parallel light of the laser beam L2 for DVD, the direction of beam diameter phi ₁ after having been converged into a parallel light of the laser beam L1 for BD, large.

  The laser light that has passed through the collimator lens 11 enters the polarization beam splitter 12 as P-polarized light. Since the polarization beam splitter 12 transmits P-polarized light and reflects S-polarized light, light (P-polarized light) incident from the collimator lens 11 side is transmitted. The light transmitted through the polarization beam splitter 12 passes through the quarter wavelength plate 13 and enters the objective lens 14.

  The objective lens 14 collects the laser beam incident through the quarter-wave plate 13 and irradiates the optical disc D with it. Further, the return light reflected from the optical disk D is incident on the objective lens 14.

Here, the objective lens 14 is configured such that the numerical aperture of the central portion of the lens is 0.45 and 0.6, and the numerical aperture of the peripheral portion of the lens is 0.85. That is, when condensed with numerical aperture of 0.85 when it is incident at a wide beam diameter phi ₁ to the objective lens 14, which is incident at a narrow beam diameter phi ₂ to the objective lens 14 0 Condensate with numerical apertures of .45 and 0.6. Therefore, the objective lens 14, when the laser light L1 for BD beam diameter phi ₁ is incident to achieve a numerical aperture of 0.85, the beam diameter phi ₂ of the CD, the laser beam L2 for DVD incident If so, a numerical aperture of 0.45 or 0.6 is achieved.

  The return light that has passed through the objective lens 14 passes through the quarter-wave plate 13 and enters the polarization beam splitter 12. This time, it passes through the quarter-wave plate 13 twice and enters the polarization beam splitter 12 as S-polarized light, and is reflected by the polarization beam splitter 12.

  The return light reflected by the polarization beam splitter 12 passes through the condenser lens 15 and is irradiated on the photodetector 16.

  The photodetector 16 converts the irradiated light into an electrical signal and outputs it to a matrix amplifier or the like.

  As described above, in the optical head 1, the three-wavelength laser module 10 in which the divergence angle of the laser beam is adjusted so as to reduce the beam diameter of the laser beam of CD and DVD and increase the beam diameter of the laser beam of BD. Used. For this reason, the optical head 1 has a simple configuration that does not require a magnification conversion mechanism or the like that expands the beam diameter, eliminates light loss due to a diaphragm or the like, and realizes a difference in numerical aperture due to the objective lens 14. Can do.

  Next, the three-wavelength laser module 10 will be described in more detail.

  As shown in FIG. 2, the three-wavelength laser module 10 includes, for example, a metal package 20 having a hollow inside, and a laser element and the like housed in the package 20. The metal package 20 is provided with a transparent exit window 21. In the three-wavelength laser module 10, the laser light emitted inside is emitted to the outside through the emission window 21.

  FIG. 3 is a diagram schematically showing the internal configuration of the package 20 of the three-wavelength laser module 10.

  As shown in FIG. 3, the three-wavelength laser module 10 includes a laser light emitting unit 31 and a reflection mirror 32 inside the package 20.

  The laser light emitting unit 31 emits laser light having three wavelengths, that is, laser light having a wavelength for CD of 785 nm, laser light having a wavelength for DVD of 660 nm, and laser light having a wavelength for BD of 405 nm in the same direction. The laser light emitted from the laser light emitting unit 31 is reflected by the reflection mirror 32, enters the emission window 21, passes through the emission window 21, and is output to the outside.

  A specific configuration of the laser emitting unit 31 is shown in FIG.

  4A is a schematic rear side view of the laser emission unit 31, and FIG. 4B is a schematic lateral side view of the laser emission unit 31, and FIG. ) Is a schematic front view of the laser light emitting unit 31. FIG.

  The laser emission unit 31 has a configuration in which a heat sink 41, a BD semiconductor laser element 42, a DVD semiconductor laser element 43, a CD semiconductor laser element 44, and a magnification correction lens 45 are integrally bonded. Yes.

  The heat sink 41 has a function as a support base for supporting the laser elements 42 to 44 and also has a function of dissipating heat generated in the laser elements 42 to 44 to the outside. The heat sink 41 is made of a material having high thermal conductivity and good conductivity, such as copper. Further, the heat sink 41 has a planar main surface 41a on which the laser elements 42 to 44 are placed.

  The BD semiconductor laser element 42 is bonded onto the main surface 41 a of the heat sink 41.

  The BD semiconductor laser element 42 is a so-called GaN-based semiconductor laser element having a semiconductor layer in which a laser structure is formed on an n-type GaN substrate. Specifically, the BD semiconductor laser element 42 includes an n-type AlGaN cladding layer, a GaInN optical waveguide layer, an active layer having a multiple quantum well (MQW) structure, a GaInN optical waveguide layer, and a p-type AlGaN on an n-type GaN substrate. The electron barrier layer, the p-type AlGaN / GaN superlattice cladding layer, and the p-type GaN contact layer are sequentially stacked.

  In such a BD semiconductor laser element 42, the n-side electrode of the n-type GaN substrate is bonded to the main surface 41 a of the heat sink 41. The BD semiconductor laser element 42 emits blue-violet laser light having an oscillation wavelength of about 405 nm in a direction parallel to the main surface 41a of the heat sink 41 from the light emitting point 42a.

  The DVD semiconductor laser element 43 is bonded onto the semiconductor layer of the BD semiconductor laser element 42. In other words, the DVD semiconductor laser element 43 is provided on the surface opposite to the surface to which the heat sink 41 of the BD semiconductor laser element 42 is bonded.

  The DVD semiconductor laser element 43 is a so-called AlGaInP semiconductor laser element having an AlGaInP semiconductor layer in which a laser structure is formed on an n-type GaAs substrate. Specifically, the semiconductor laser device 43 for DVD includes an n-type AlGaInP cladding layer, an AlGaInP optical waveguide layer, an active layer having a single quantum well (SQW) structure or an MQW structure, an AlGaInP optical waveguide layer on an n-type GaAs substrate. The p-type AlGaInP cladding layer and the p-type GaAs contact layer are sequentially stacked.

  Such a semiconductor laser element 43 for DVD is bonded to the semiconductor laser element 42 for BD on the semiconductor layer side. The DVD semiconductor laser element 43 emits red laser light having an oscillation wavelength of about 660 nm in a direction parallel to the main surface 41a of the heat sink 41 from the light emitting point 43a.

  The CD semiconductor laser element 44 is bonded onto the semiconductor layer of the BD semiconductor laser element 42. That is, the CD semiconductor laser element 44 is provided on the opposite side of the surface to which the heat sink 41 of the BD semiconductor laser element 42 is bonded.

  The CD semiconductor laser element 44 is a so-called AlGaAs semiconductor laser element having an AlGaAs semiconductor layer having a laser structure formed on an n-type GaAs substrate. Specifically, the semiconductor laser device for CD 44 includes an n-type AlGaAs cladding layer, an AlGaAs optical waveguide layer, an active layer having an SQW structure or an MQW structure, an AlGaAs optical waveguide layer, and a p-type AlGaAs cladding layer on an n-type GaAs substrate. And a p-type GaAs contact layer are sequentially stacked.

  Such a semiconductor laser element for CD 44 is bonded to the semiconductor laser element for BD on the semiconductor layer side. The CD semiconductor laser element 44 emits red laser light having an oscillation wavelength of about 785 nm in a direction parallel to the main surface 41a of the heat sink 41 from the light emitting point 43a.

  The n-type GaAs substrates of the DVD semiconductor laser element 43 and the CD semiconductor laser element 44 may be shared.

  As described above, the laser emission unit 31 includes the BD semiconductor laser element 42, the DVD semiconductor laser element 43, and the CD semiconductor laser element 44 which are integrally formed.

  Further, in the laser emission unit 31, the laser emission direction of the BD semiconductor laser element 42 is the same as the laser emission direction of the DVD semiconductor laser element 43 and the CD semiconductor laser element 44.

  Here, the position of the light emitting point 42a of the BD semiconductor laser element 42 is greater than the position of the light emitting points 43a and 44a of the DVD semiconductor laser element 43 and the CD semiconductor laser element 44 with respect to the traveling direction of the laser light. Located on the back side. Therefore, the optical path of the laser light emitted from the BD semiconductor laser element 42 is longer by the difference than the optical path of the laser light emitted from the DVD semiconductor laser element 43 and the CD semiconductor laser element 44. Yes.

  A magnification correction lens 45 is provided on the optical path of the laser light emitted from the BD semiconductor laser element 42 and in the portion of the optical path difference (that is, in the vicinity of the light emitting point 42a). That is, a portion between the light emitting point 42a of the BD semiconductor laser element 42 and the light emitting point 43a of the DVD semiconductor laser element 43 (or the light emitting point 44a of the CD semiconductor laser element 44) in the laser traveling direction, A magnification correction lens 45 is provided on the optical path of the laser light emitted from the semiconductor laser element 42 for use. The light emitting point 43a of the DVD semiconductor laser element 43 and the light emitting point 44a of the CD semiconductor laser element 44a have the same position in the laser traveling direction.

  The magnification correction lens 45 is a spherical lens, for example, and is held so as to be sandwiched between the semiconductor laser element 43 for DVD and the main surface 41 a of the heat sink 41.

  Such a magnification correction lens 45 is a positive power lens and has a function of enlarging the laser light emitted from the BD semiconductor laser element 42.

  Therefore, the magnification of the optical system constituting the optical path of the laser light emitted from the BD semiconductor laser element 42 constitutes the optical path of the laser light emitted from the DVD semiconductor laser element 43 and the CD semiconductor laser element 44. It becomes higher than the magnification of the optical system.

As a result, the laser beams having the three wavelengths are output as divergent light from the emission window 21. At the time of output, the laser beams emitted from the DVD semiconductor laser element 43 and the CD semiconductor laser element 44 are output. than the divergence angle theta _2, the direction of the divergence angle theta ₁ of the laser beam emitted from the BD semiconductor laser element 42 is increased. In other words, the divergence angle θ ₁ of the BD laser beam is wider than the divergence angle θ ₂ of the laser beam for CD and DVD.

In this way, by making the divergence angle θ ₁ of the BD laser light wider than the divergence angle θ ₂ of the CD and DVD laser light, the beam of the CD and DVD laser light on the objective lens 14 is increased. The diameter can be reduced and the beam diameter of the BD laser light on the objective lens 14 can be increased.

  Therefore, in the three-wavelength laser module 10, the configuration of the optical head can be greatly simplified except for the magnification conversion mechanism and the diaphragm mechanism that have been conventionally required.

  In this example, the positive power lens is provided in the optical path of the laser light emitted from the BD semiconductor laser element 42. However, in the present invention, the negative power lens is provided for the laser light for CD and DVD. You may provide in an optical path. In this case, the positions of the light emitting points 43a and 44a of the DVD semiconductor laser element 43 and the CD semiconductor laser element 44 are located behind the light emitting point 42a of the BD semiconductor laser element 42 in the traveling direction of the laser beam. There is a need to.

It is a block diagram of an optical head to which the present invention is applied. It is an external view of a three-wavelength laser device. It is a typical block diagram inside a 3 wavelength laser device. It is a typical side view of the laser light emission part inside a 3 wavelength laser device. It is a block diagram of the conventional optical head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical head, 10 3 wavelength laser module, 11 Collimator lens, 12 Polarization beam splitter, 13 1/4 wavelength plate, 14 Objective lens, 15 Condensing lens, 16 Photo detector, 21 Laser light emission part, 32 Reflection mirror, 41 Heat sink, 42 BD semiconductor laser device, 43 DVD semiconductor laser device, 44 CD semiconductor laser device, 45 magnification correction lens

Claims (18)

A support base having a planar main surface; a first semiconductor laser element which is provided on the main surface of the support base and emits a first laser beam having a wavelength λ ₁ parallel to the main surface; A second laser beam having a wavelength λ ₂ different from the wavelength λ _{1 in the} same direction as the laser beam emitted from the first semiconductor laser device, which is provided on the first semiconductor laser device and is parallel to the main surface of the support base. A laser emitting section having a second semiconductor laser element that emits laser light, and an enlargement or reduction optical element;
The first laser beam and the second laser beam are incident, and an emission optical system that emits these laser beams to the outside, and
The emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam. A laser emitting device, characterized in that the laser emitting device is provided in the separated portion in the optical path of the semiconductor laser element located on the rear side in the traveling direction. The laser emission unit is stored in one storage unit,
The laser emitting apparatus according to claim 1, wherein the emission optical system is an emission window formed of a transparent member provided in a storage portion. The laser emitting apparatus according to claim 1, wherein the first semiconductor laser element is a laser element using a GaN substrate. The laser emitting apparatus according to claim 1, wherein the second semiconductor laser element is a laser element using a GaAs substrate. The first semiconductor laser element is a laser element using a GaN substrate,
The second semiconductor laser element is a laser element using a GaAs substrate,
The expansion or reduction optical element is a positive power lens when inserted into the optical path of the first semiconductor laser element, and is negative when inserted into the optical path of the second semiconductor laser element. The laser emitting device according to claim 1, wherein the laser emitting device is a power lens. A support base having a planar main surface; a first semiconductor laser element which is provided on the main surface of the support base and emits a first laser beam having a wavelength λ ₁ parallel to the main surface; A _second wavelength λ ₂ longer than wavelength λ _{1 in the} same direction as the laser beam provided on the first semiconductor laser element and parallel to the main surface of the support base and emitted from the first semiconductor laser element. And a third laser having a wavelength λ ₃ longer than the wavelength λ _{2 in the} same direction as the second laser light provided on the first semiconductor laser element. A laser light emitting unit having a third semiconductor laser element that emits light;
The first laser beam, the second laser beam, and the third laser beam are incident, and a synthesis optical system that emits these laser beams to the outside, and
The emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are separated from each other by a predetermined distance in the traveling direction of the laser beam, and the emission position of the second semiconductor laser element and the third semiconductor The emission position of the laser element is the same position in the traveling direction of the laser beam, and the enlargement or reduction optical element is in the optical path of the semiconductor laser element whose emission position is located behind the traveling direction of the laser beam. A laser emitting device, characterized in that the laser emitting device is provided in the separated portion. The laser emission unit is stored in one storage unit,
The laser emitting apparatus according to claim 6, wherein the emission optical system is an emission window configured by a transparent member provided in a storage portion. The laser emitting apparatus according to claim 6, wherein the first semiconductor laser element is a laser element using a GaN substrate. The laser emitting apparatus according to claim 6, wherein the second semiconductor laser element and the third semiconductor laser element are laser elements using a GaAs substrate. The first semiconductor laser element is a laser element using a GaN substrate,
The second semiconductor laser element and the third semiconductor laser element are laser elements using a GaAs substrate,
The enlarging or reducing optical element is a positive power lens when inserted in the optical path of the first semiconductor laser element, and is in the optical path of the second semiconductor laser element and the third semiconductor laser element. The laser emitting device according to claim 6, wherein when the lens is inserted, the lens has a negative power. In an optical head that emits laser light to an optical disc,
A laser emitting device that outputs laser light of different wavelengths from one exit window according to the type of the optical disc;
A collimator lens that collimates the laser beam output from the laser emitting device;
The numerical aperture of the central portion is low, the laser light is made into parallel light that has passed through the collimator lens, and includes an objective lens that irradiates the optical disk with the incident light,
The laser emitting device is
A support base having a planar main surface; a first semiconductor laser element which is provided on the main surface of the support base and emits a first laser beam having a wavelength λ ₁ parallel to the main surface; A second laser beam having a wavelength λ ₂ different from the wavelength λ _{1 in the} same direction as the laser beam emitted from the first semiconductor laser device, which is provided on the first semiconductor laser device and is parallel to the main surface of the support base. A laser light emitting unit having a second semiconductor laser element that emits laser light and a magnifying or reducing optical element is housed. The emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are The enlargement or reduction optical element is provided in the separation part in the optical path of the semiconductor laser element whose emission position is located behind the laser beam in the traveling direction. To be A featured optical head. The optical head according to claim 11, wherein the first semiconductor laser element is a laser element using a GaN substrate. The optical head according to claim 11, wherein the second semiconductor laser element is a laser element using a GaAs substrate. The first semiconductor laser element is a laser element using a GaN substrate,
The second semiconductor laser element is a laser element using a GaAs substrate,
The expansion or reduction optical element is a positive power lens when inserted into the optical path of the first semiconductor laser element, and is negative when inserted into the optical path of the second semiconductor laser element. The laser emitting device according to claim 11, wherein the laser emitting device is a power lens. In an optical head that emits laser light to an optical disc,
A laser emission device that outputs laser beams of three different wavelengths from one emission window according to the type of the optical disc;
A collimator lens that collimates the laser beam output from the laser emitting device;
The numerical aperture of the central portion is low, the laser light is made into parallel light that has passed through the collimator lens, and includes an objective lens that irradiates the optical disk with the incident light,
The laser emitting device is
A support base having a planar main surface; a first semiconductor laser element which is provided on the main surface of the support base and emits a first laser beam having a wavelength λ ₁ parallel to the main surface; A first wavelength λ ₂ longer than the wavelength λ _{1 in a} direction different from the laser beam provided on the first semiconductor laser element and parallel to the main surface of the support base and emitted from the first semiconductor laser element. A second semiconductor laser element that emits two laser beams, and a third semiconductor laser element that is provided on the first semiconductor laser element and has a wavelength λ ₃ longer than the wavelength λ _{2 in the} same direction as the second laser beam A laser emitting unit having a third semiconductor laser element that emits laser light is housed, and the emission position of the first semiconductor laser element and the emission position of the second semiconductor laser element are predetermined in the traveling direction of the laser light. Separated by a distance, the second semiconductor The emission position of the laser element and the emission position of the third semiconductor laser element are the same position in the traveling direction of the laser beam, and the enlargement or reduction optical element has an emission position behind the traveling direction of the laser beam. An optical head characterized in that the optical head is provided in the separated portion in the optical path of the semiconductor laser element positioned in the position. The optical head according to claim 15, wherein the first semiconductor laser element is a laser element using a GaN substrate. 16. The optical head according to claim 15, wherein the second semiconductor laser element and the third semiconductor laser element are laser elements using a GaAs substrate. The first semiconductor laser element is a laser element using a GaN substrate,
The second semiconductor laser element and the third semiconductor laser element are laser elements using a GaAs substrate,
The enlarging or reducing optical element is a positive power lens when inserted in the optical path of the first semiconductor laser element, and is in the optical path of the second semiconductor laser element and the third semiconductor laser element. The optical head according to claim 15, wherein the optical head is a lens having a negative power when inserted.

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