WO2010140404A1 - 面発光半導体レーザ、光記録ヘッド及び光記録装置 - Google Patents
面発光半導体レーザ、光記録ヘッド及び光記録装置 Download PDFInfo
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- WO2010140404A1 WO2010140404A1 PCT/JP2010/053635 JP2010053635W WO2010140404A1 WO 2010140404 A1 WO2010140404 A1 WO 2010140404A1 JP 2010053635 W JP2010053635 W JP 2010053635W WO 2010140404 A1 WO2010140404 A1 WO 2010140404A1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1384—Fibre optics
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
- G11B5/3109—Details
- G11B5/313—Disposition of layers
- G11B5/3133—Disposition of layers including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure
- G11B5/314—Disposition of layers including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
- G11B5/6088—Optical waveguide in or on flying head
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1387—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector using the near-field effect
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B2005/0002—Special dispositions or recording techniques
- G11B2005/0005—Arrangements, methods or circuits
- G11B2005/0021—Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/1028—Coupling to elements in the cavity, e.g. coupling to waveguides adjacent the active region, e.g. forward coupled [DFC] structures
- H01S5/1032—Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/11—Comprising a photonic bandgap structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
- H01S5/185—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL]
- H01S5/187—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL] using Bragg reflection
Definitions
- the present invention relates to a surface emitting semiconductor laser, an optical recording head, and an optical recording apparatus.
- the recording medium is locally heated at the time of recording to cause magnetic softening, recording is performed in a state where the coercive force is reduced, and then the heating is stopped and natural cooling is performed. This is a method for guaranteeing bit stability.
- the heat-assisted magnetic recording method it is desirable to heat the recording medium instantaneously, and the heating mechanism and the recording medium are not allowed to contact each other. For this reason, heating is generally performed by utilizing absorption of light, and the method of using light for heating is called a light-assisted method.
- the light used is heated. A minute light spot below the wavelength is required.
- Patent Document 1 discloses the following as an optical recording head that uses near-field light (also referred to as near-field light) as a minute light spot.
- near-field light also referred to as near-field light
- the optical recording head disclosed in Patent Document 1 includes a waveguide having a write magnetic pole, a core layer adjacent to the write magnetic pole, and a cladding layer.
- the core layer is provided with a diffraction grating (referred to as a grating coupler) that introduces light into the core layer.
- a grating coupler irradiated with laser light
- the laser light is introduced into the core layer.
- the light introduced into the core layer converges on a focal point located near the tip of the core layer, the recording medium is heated by the light emitted from the tip, and writing is performed by the writing magnetic pole.
- the element having a waveguide with a condensing function is called a waveguide type solid immersion mirror (PSIM), and the PSIM of Patent Document 1 is provided with a grating coupler as described above. .
- PSIM waveguide type solid immersion mirror
- the recording head portion provided with the above-described PSIM may be called a HAMR (Heat Assisted Magnetic Recording) head.
- a surface emitting laser VCSEL: vertical cavity surface emitting laser
- VCSEL vertical cavity surface emitting laser
- a mechanically fixed slider is disclosed.
- Patent Documents 1 and 2 considers a method for efficiently introducing laser light from a grating coupler into a waveguide.
- the present invention has been made in view of the above problems, and an object of the present invention is to provide a surface emitting laser that generates laser light that is efficiently introduced into a waveguide from a grating coupler (diffraction grating) and a surface emitting laser that includes the surface emitting laser.
- An optical recording head and an optical recording apparatus are provided.
- a light source A waveguide for irradiating the recording medium with light from the light source coupled via a diffraction grating, and The light source is Having a two-dimensional photonic crystal structure on the surface facing the waveguide;
- An optical recording head characterized in that the two-dimensional photonic crystal structure is a surface emitting laser in which a region excluding a region facing the diffraction grating is covered and a region facing the diffraction grating is a surface emitting region.
- the surface-emitting laser is a surface-emitting semiconductor laser in which a member covering the two-dimensional photonic crystal structure is a first electrode, and a resonator region is formed by a second electrode facing the first electrode. 2.
- the surface-emitting laser is characterized in that a member that covers the two-dimensional photonic crystal structure is a light-shielding member, and the surface-emitting laser emits light by excitation light that is irradiated on the opposite side of the surface-emitting laser where the light-shielding member is present. 2.
- optical recording head according to any one of 1 to 3, wherein the light source is fixed to the waveguide.
- An optical excitation source that emits excitation light for emitting the surface-emitting laser; 4. The optical recording head according to item 3, wherein the excitation light does not irradiate the surface emitting region.
- the recording medium is a magnetic recording medium, 6.
- a surface-emitting semiconductor laser that is disposed opposite to a waveguide having a grating coupler and emits light introduced into the waveguide to the grating coupler,
- a semiconductor laminate having a first cladding layer, a second cladding layer, and an active layer sandwiched between the first cladding layer and the second cladding layer and generating light of a predetermined wavelength by carrier injection;
- a first electrode connected to the first cladding layer;
- the first cladding layer has a refractive index that changes in a direction corresponding to the predetermined wavelength in an in-plane direction, is optically coupled to the active layer, and light generated in the active layer is introduced and introduced.
- a diffraction grating configured to diffract the laser light of the predetermined wavelength and to oscillate, and to change the traveling direction of at least part of the light to a direction perpendicular to the in-plane direction;
- the diffraction grating is coated with a region excluding the region facing the grating coupler, facing the grating coupler, and a region emitting the light converted in the vertical direction is a surface emitting region,
- a surface-emitting semiconductor laser wherein a member that covers the diffraction grating is the first electrode, and a resonator region that performs laser oscillation is formed with the second electrode facing the first electrode.
- the surface emitting region is provided at an end of the diffraction grating,
- the light intensity distribution of the light emitted from the surface emitting region is maximum in the vicinity of the boundary between the resonator region and the surface emitting region in the first direction from the resonator region to the surface emitting region, 8.
- the concave portion disposed in the first clad layer with the period is filled with a material having a refractive index different from that of the material of the first clad layer.
- the concave portion is a hole-shaped concave portion, and the hole-shaped concave portions of the resonator region and the surface emitting region are arranged in a square lattice along the first direction and a direction perpendicular to the first direction.
- the surface emitting semiconductor laser as described in 10 above.
- the concave portion of the resonator region is a hole-shaped concave portion arranged in a square lattice along the first direction and a direction perpendicular to the first direction
- the concave portion of the surface light emitting region is a stripe groove-shaped concave portion along a direction perpendicular to the first direction, and the period of the first direction is arranged at the same period as the period of the square lattice. 11.
- the surface emitting semiconductor laser as described in 10 above.
- the concave portion is a hole-shaped concave portion, and the hole-shaped concave portion of the resonator region is disposed in a square lattice along the first direction and a direction perpendicular to the first direction,
- the hole-shaped recess in the surface light emitting region has a period in a direction perpendicular to the first direction that is the same as a period of the square lattice in the resonator region, and a period in the first direction is a period of the square lattice.
- the concave portion of the resonator region is a hole-shaped concave portion arranged in a square lattice along the first direction and a direction perpendicular to the first direction
- the concave portion of the surface light emitting region is a stripe groove-shaped concave portion along a direction perpendicular to the first direction, and the period of the first direction is arranged at a period different from the period of the square lattice. 11.
- the surface emitting semiconductor laser as described in 10 above.
- the recess of the surface light emitting region decreases or increases in width of the recess in the first direction and is perpendicular to the axis perpendicular to the main plane.
- the surface emitting semiconductor laser as described in 13 or 14 above, wherein the surface emitting semiconductor laser is asymmetric.
- the cross section in the depth direction of the concave portion from the main plane opposite to the surface of the first cladding layer with respect to the active layer is the same, and the cross sectional area of the concave portion in the resonator region and the surface emitting region are the same.
- an optical recording head that records information using light on a recording medium
- the surface emitting semiconductor laser according to any one of 7 to 19,
- the waveguide that propagates the introduced light toward the recording medium is introduced into the side surface of the slider that is substantially perpendicular to the recording surface of the recording medium.
- 21 The optical recording head as described in 20 above, wherein the surface emitting semiconductor laser is fixed to the waveguide.
- optical recording head according to 20 or 21, An optical recording apparatus comprising the recording medium.
- the laser light emitted from the surface emitting semiconductor laser and irradiating the grating coupler has an intensity distribution that can be efficiently introduced into the waveguide. .
- the surface emitting semiconductor laser of the present invention can generate laser light that is efficiently introduced into a waveguide including a grating coupler.
- the optical recording head of the present invention also includes a waveguide having a grating coupler (diffraction grating), and a surface emitting laser that irradiates the grating coupler with a light intensity distribution such that light is efficiently introduced into the waveguide. And.
- a grating coupler diffiffraction grating
- a surface emitting laser that irradiates the grating coupler with a light intensity distribution such that light is efficiently introduced into the waveguide.
- the optical recording head of the present invention can efficiently irradiate the recording medium with light from the light source.
- FIG. 2 is a diagram conceptually showing a cross section of an optical recording head and its peripheral portion. It is a figure which shows the front view of a waveguide. It is a figure which shows the cross section in the axis
- FIG. 1 It is a figure which shows an example of schematic structure of a light source typically, (a) is a top view, (b) is sectional drawing. (A) And (b) is a figure which shows the example of the combination of a light source and a waveguide. It is a figure which shows an example of schematic structure of a light source typically, (a) is a top view, (b) is sectional drawing. It is a figure which shows the example of the combination of a light source and a waveguide. It is a figure which shows the example of a plasmon antenna. It is a figure which shows notionally the optical recording head of another example, and its peripheral part in a cross section.
- FIG. 1 It is a figure which shows the cross section of the waveguide in the optical recording head of another example, and the cross section of a light source.
- FIG. 1 It is a figure which shows the schematic structure of an example of a light source typically, (a) is a top view, (b) is sectional drawing. It is a figure which shows the schematic structure of an example of a light source typically, (a) is a top view, (b) is sectional drawing. (A) And (b) is sectional drawing which shows typically schematic structure of an example of a light source. It is a top view which shows typically schematic structure of an example of a light source. It is a figure which shows typically an example schematic structure of a light source, (a) is a top view, (b) is sectional drawing.
- (A) And (b) is a figure which shows the example of the combination of a light source and a waveguide. It is a figure which shows the schematic structure of an example of a light source typically, (a) is a top view, (b) is sectional drawing. It is a figure which shows the example of the combination of a light source and a waveguide.
- the present invention relates to a surface emitting semiconductor laser that emits laser light (also referred to as light) that can be efficiently introduced into a waveguide having a grating coupler, and an optical recording head including the surface emitting semiconductor laser.
- This optical recording head can be used in, for example, an optical recording apparatus that performs recording on a magneto-optical recording medium or an optical recording medium.
- FIG. 1 shows a schematic configuration example of an optical recording apparatus (for example, a hard disk apparatus) equipped with an optically assisted magnetic recording head including a surface emitting semiconductor laser according to an embodiment of the present invention.
- the optical recording apparatus 100 includes the following (1) to (6) in the housing 101.
- Recording disk (recording medium) 102 (2) Suspension 104 supported by arm 105 that is rotatably provided in the direction of arrow A (tracking direction) with support shaft 106 as a fulcrum.
- Tracking actuator 107 attached to arm 105 and rotationally driving arm 105 (4)
- An optically assisted magnetic recording head (hereinafter referred to as an optical recording head 103) including the suspension 104 and the slider 30 attached to the tip of the suspension 104 via a coupling member 104a.
- the optical recording apparatus 100 is configured such that the slider 30 can move relatively while floating on the disk 102.
- FIG. 2 conceptually shows, in section, the optical recording head 103 and its peripheral part as an example of the optical recording head 103 according to the present invention.
- the optical recording head 103 is an optical recording head that uses light for information recording on the disk 102, and includes a slider 30, a waveguide 20, a surface emitting semiconductor laser (hereinafter, a light source 70) that is a light source, a magnetic recording unit 35, and a magnetic recording head.
- a light source 70 that is a light source
- a magnetic recording unit 35 a magnetic recording unit 35
- An information reproducing unit 36 and the like are provided.
- the waveguide 20 is also referred to as a waveguide type solid immersion mirror (PSIM), and has a diffraction grating (also referred to as a grating coupler) for introducing light into the waveguide.
- PSD waveguide type solid immersion mirror
- the light source 70 irradiates the grating coupler with light introduced into the waveguide 20 and is a two-dimensional photonic crystal structure (a structure in which the refractive index in the in-plane direction of the structure periodically changes). Is a surface emitting semiconductor laser.
- the slider 30 moves relative to the disk 102, which is a magnetic recording medium, while flying, and it is desirable to use a hard material with high wear resistance as the material of the slider 30, for example, Al A ceramic material containing 2 O 3 , AlTiC, zirconia, TiN, or the like may be used. Further, as a wear prevention treatment, a surface treatment such as a DLC (Diamond Like Carbon) coating may be performed on the surface of the slider 30 on the disk 102 side in order to increase wear resistance.
- a surface treatment such as a DLC (Diamond Like Carbon) coating may be performed on the surface of the slider 30 on the disk 102 side in order to increase wear resistance.
- the surface of the slider 30 facing the disk 102 has an air bearing surface 32 (also referred to as an ABS (Air Bearing Surface) surface) for improving the flying characteristics.
- ABS Air Bearing Surface
- the flying of the slider 30 needs to be stabilized in the state of being close to the disk 102, and it is necessary to appropriately apply a pressure for suppressing the flying force to the slider 30.
- the suspension 104 fixed on the slider 30 has a function of appropriately applying a pressure for suppressing the floating force of the slider 30 in addition to a function of tracking the slider 30.
- the slider 30 is provided with a waveguide 20 and a light source 70 on a side surface on the inflow side of the disk 102 that is substantially perpendicular to the recording surface of the disk 102.
- the light source 70 is fixed close to the waveguide 20 so that light emitted from the light source 70 irradiates a grating coupler (hereinafter referred to as a coupler) which is a diffraction grating provided in the waveguide 20.
- a coupler grating coupler
- the fact that the waveguide 20 and the light source 70 are integrated and fixed to the slider 30 means that light emitted from the light source 70 is stably introduced into the waveguide 20 without depending on the movement of the slider 30. It is preferable because magneto-optical recording can be performed stably.
- the light emitted from the light source 70 is introduced into the waveguide 20, and the light introduced into the waveguide 20 travels to the lower end surface 24 of the waveguide 20 and is applied to the disk 102 as irradiation light for heating the disk 102. It is injected towards.
- a plasmon antenna 24d which will be described later, provided at or near the position where the light on the lower end surface 24 is emitted is omitted.
- the temperature of the irradiated portion of the disk 102 temporarily rises, and the disk 102 is maintained. Magnetic force decreases. Magnetic information is written by the magnetic recording unit 35 to the portion where the light is irradiated and the coercive force is lowered.
- the magnetic recording unit 35 is preferably provided adjacent to the waveguide 20 as close as possible to efficiently perform magnetic recording on the recording surface of the disk 102 heated by light. Recording by rotating the disk 102 is also preferable. It is preferable to be disposed on the downstream side of the waveguide 20 from the moving direction of the surface (the direction of the arrow 102a). Further, a magnetic information reproducing unit 36 for reading magnetic recording information written on the disk 102 may be provided on the disk exit side of the magnetic recording unit 35 or the disk entry side of the waveguide 20.
- the waveguide 20 will be described.
- a front view (transmission diagram) of the waveguide 20A is schematically shown in FIG. 3, and a cross-sectional view along the axis C in FIG. 3 is schematically shown in FIG. FIG. 4 also shows a light source 70A that emits light introduced into the waveguide 20A.
- the waveguide 20A has a core layer 21, a lower cladding layer 22, and an upper cladding layer 23 that constitute the waveguide, and a grating coupler (hereinafter referred to as coupler 29) that introduces light 50a emitted from the light source 70A into the core layer 21. Is formed.
- the waveguide 20A can be composed of a plurality of layers made of materials having different refractive indexes, and the refractive index of the core layer 21 is larger than the refractive indexes of the lower cladding layer 22 and the upper cladding layer 23.
- the waveguide 20A is configured by this refractive index difference, and the light in the core layer 21 is confined in the core layer 21, efficiently travels in the direction of the arrow 25, and reaches the lower end surface 24.
- the refractive index of the core layer 21 is preferably about 1.45 to 4.0, and the refractive indexes of the lower cladding layer 22 and the upper cladding layer 23 are preferably about 1.0 to 2.0. It is not limited.
- the core layer 21 is formed of Ta 2 O 5 , TiO 2 , ZnSe or the like, and the thickness is preferably in the range of about 20 nm to 500 nm, but is not limited to this range.
- the lower cladding layer 22 and the upper cladding layer 23 are formed of SiO 2 , air, Al 2 O 3, etc., and the thickness is preferably in the range of about 200 nm to 2000 nm, but is not limited to this range. Absent.
- the core layer 21 has side surfaces 26 and 27 formed so as to substantially form a parabolic contour so as to reflect the light combined by the coupler 29 to the focal point F so as to be reflected toward the focal point F.
- the center axis whose contour is symmetrical to the parabola is indicated by an axis C (a line perpendicular to the quasi-line (not shown) and passing through the focal point F), and the focal point of the parabola is indicated as the focal point F.
- the side surfaces 26 and 27 may be provided with a reflective material such as gold, silver, and aluminum to help reduce light reflection loss.
- the thickness of the side surfaces 26, 27 is very thin compared to other dimensions of the core layer 21, so that the outline of the core layer 21 is substantially defined.
- the lower end surface 24 of the core layer 21 of the waveguide 20A has a planar shape in which the tip of the parabola is cut in a direction substantially perpendicular to the axis C. Since the light 50c radiated from the focal point F diverges rapidly, setting the shape of the lower end surface 24 to a plane allows the focal point F to be placed closer to the disk 102, and the collected light diverges greatly. This is preferable because it is incident on the disk 102 before the recording.
- the focal point F may be formed on the lower end surface 24, or the focal point F may be formed outside the lower end surface 24.
- the lower end surface 24 is a flat surface, but it is not necessarily a flat surface.
- a plasmon antenna 24d for generating near-field light may be disposed at or near the focal point F of the core layer 21.
- a specific example of the plasmon antenna 24d is shown in FIG.
- (a) is a plasmon antenna 24d made of a triangular flat metal thin film
- (b) is a plasmon antenna 24d made of a bow-tie flat metal thin film, both having a vertex P with a radius of curvature of 20 nm or less. It consists of an antenna.
- (c) is a plasmon antenna 24d made of a flat metal thin film having an opening, and is made of an antenna having a vertex P with a curvature radius of 20 nm or less.
- Examples of the material for the metal thin film of any plasmon antenna 24d include aluminum, gold, and silver.
- the light incident on the coupler 29 and introduced into the waveguide 20 ⁇ / b> A is determined from the effective refractive index of the waveguide mode of the core layer 21 and the period of the coupler 29 to determine an appropriate incident angle to the coupler 29 with the highest introduction efficiency. .
- the appropriate incident angle also depends on the wavelength of the incident light. This incident angle may be substantially perpendicular to the waveguide 20A as necessary (incident angle is 0 °), or may have an appropriate angle.
- FIG. 4 shows an example in which the incident angle is 0 °.
- the light 50a has the strongest light intensity at the leading position in the direction in which the light introduced into the waveguide 20A travels (the direction of the + y direction, the direction of the arrow 25), and the direction in which the light introduced into the core layer of the waveguide 20A travels.
- the intensity distribution has a shape having an inclination that decreases exponentially as it goes in the opposite direction ( ⁇ y direction) to the column shape having a thickness in the width direction (x direction) of the coupler 29.
- the light intensity distribution 50a having an exponential shape with such an inclination has a general circular shape in the irradiation region irradiated with the coupler 29, and the light intensity distribution in the diameter direction passing through the center of the circular shape is the center of the circle. Compared with the Gaussian light having the highest intensity, the light is efficiently introduced from the coupler 29 into the core layer 21.
- the efficient introduction from the coupler 29 to the core layer 21 means that the core layer 21 is moved to the arrow 25 due to the backward property of light. It can be estimated from the case where light traveling in the opposite direction is emitted from the coupler 29. In other words, the light traveling in the opposite direction through the core layer 21 is diffracted to the outside from the vicinity of the boundary with the coupler 29 where the loss due to the coupler 29 is small, and the loss due to the coupler 29 proceeds toward the coupler 29 side. The intensity of light diffracted to the outside increases and decreases.
- the width of the oscillation region whose inclination corresponds to the thickness of the exponential shape is about several ⁇ m, which is narrower than the width of the coupler 29, for example, about 50 ⁇ m.
- the width of the oscillation region of about several ⁇ m
- the width of the oscillation region is increased to match the width of the coupler 29
- the light intensity distribution in the wavelength and width direction becomes multimode, and the coupler 29
- the optimum shape and wavelength cannot be obtained.
- the semiconductor laser including a two-dimensional diffraction grating (two-dimensional photonic band structure) disclosed in Japanese Patent No. 398933 and enabling surface emission.
- a beam emitted from this semiconductor laser a very narrow emission angle (1.8 °) is obtained in a far-field image, but the beam shape (light intensity distribution) is not disclosed.
- the inventors have energetically studied a surface emitting semiconductor laser that generates light having a light intensity distribution such that the slope with the above-described thickness is such that light is introduced into the core layer 21 more efficiently than the coupler 29 and has an exponential function shape.
- the surface emitting semiconductor laser (light source) according to the present invention will be described below.
- FIG. 5 schematically shows an example of a schematic configuration of a two-dimensional photonic crystal surface emitting semiconductor laser which is a light source 70A according to the present invention.
- FIG. 5A is a top view of the light source 70A
- FIG. 5B is a cross-sectional view taken along the line G-G ′ of FIG.
- the light source 70 ⁇ / b> A is formed on the substrate 1, the second cladding layer 2 formed on one main surface of the substrate 1, the active layer 3 formed on the second cladding layer 2, and the active layer 3.
- the semiconductor laminated portion having the first cladding layer 5 and the contact layer 6, the first electrode 7 formed on the contact layer 6, and the other main surface of the substrate 1 facing the one main surface.
- the second electrode 8 is provided.
- the first electrode 7 is provided so as to cover a part of a recess 10 having a two-dimensional photonic crystal structure, which will be described later, and the second electrode 8 is provided on the entire surface of the other main surface.
- the two-dimensional photonic crystal structure has a portion between the first electrode 7 and the second electrode 8 and a portion in a state where there is no first electrode and is open, Laser light is selectively emitted from the surface on which the first electrode 7 is formed.
- the first electrode 7 and the second electrode do not transmit the light emitted from the light source 70A.
- the substrate 1 is, for example, an n-type GaAs substrate.
- the second cladding layer 2 is, for example, an n-type semiconductor layer using electrons as carriers, and is formed of, for example, n-type Al 0.4 Ga 0.6 As.
- the first cladding layer 5 is a p-type semiconductor layer using holes (holes) as carriers, for example, and is formed of p-type Al x Ga (1-x) As, for example.
- the contact layer 6 is a p-type semiconductor layer having, for example, holes (holes) as carriers, and is made of, for example, p + -type GaAs.
- each semiconductor layer in the first cladding layer 5 and the second cladding layer 2 is not limited to the above.
- a structure having p-type and n-type semiconductor layers having different conductivity types on the upper layer (on the first cladding layer 5 side) of the active layer 3 may be used, such as a buried tunnel junction (BTJ) type. .
- BTJ buried tunnel junction
- the active layer 3 is sandwiched between the second cladding layer 2 and the semiconductor layer composed of the contact layer 6 and the first cladding layer 5, and generates (emits) light by carrier injection.
- the active layer 3 can employ known general materials and structures, and the materials, structures, and the like are selected so as to emit light having a predetermined wavelength according to the intended use.
- the active layer 3 may have a strained quantum well structure including, for example, a three-period InGaAs well layer, a GaAs barrier layer, and a separation confinement layer (SCH (Separate Confinement Heterostructure) layer).
- SCH Separatate Confinement Heterostructure
- the first cladding layer 5 and the second cladding layer 2 are made of a material having a refractive index lower than that of the active layer 3 and have a function of confining light in the active layer 3.
- the refractive index of the first cladding layer 5 is preferably higher than the refractive index of the second cladding layer 2. Even if a two-dimensional photonic crystal structure is formed by increasing the refractive index of the first cladding layer 5, the average refractive index of the first cladding layer 5 does not decrease too much. This prevents a decrease in the proportion of light distributed in the layer in which the photonic crystal structure is formed, and thus a decrease in the proportion of light coupled to the diffraction grating (photonic crystal structure) (referred to as an optical coupling coefficient). Can be prevented.
- the first cladding layer 5 and the second cladding layer 2 form a double heterojunction with the active layer 3 interposed therebetween, confine carriers, and concentrate carriers contributing to light emission in the active layer 3.
- the contact layer 6 is disposed between the first electrode 7 and the first clad layer 5 and electrically connects them.
- Other layers such as a carrier stop layer functioning as a potential barrier against electrons traveling from the active layer 3 to the first cladding layer 5 due to carrier overflow may be interposed between the first cladding layer 5 and the active layer 3. .
- the first clad layer 5 and the contact layer 6 have a plurality of hole-shaped recesses 10 having a period along the x direction and the y direction perpendicular to the x direction.
- the two-dimensional photonic crystal structure has a two-dimensional refractive index period, and substances having refractive indexes different from those of the substances forming the first cladding layer 5 and the contact layer 6 are orthogonal to each other as lattice points. It is formed by arranging in two directions x and y with a predetermined period (lattice interval, lattice constant).
- the lattice point is a square lattice composed of cylindrical recesses 10 formed in the first cladding layer 5 and the contact layer 6.
- the shape of the recess 10 is a cylindrical shape, but is not limited to this shape, and may be a quadrangular prism, a triangular prism, a conical shape, or the like.
- the inside of the recess of the recess 10 may be filled with a material having a refractive index different from that of the material forming the first cladding layer 5.
- the material of the first cladding layer 5 may be Al 0.4 Ga 0.6.
- the material filling the recess 10 may be SiO 2 (refractive index 1.5), SiN (refractive index 2.0), or the like.
- SiO 2 which is a material filling the recess 10 may be provided on the entire surface of the contact layer 6 as a protective film.
- the recess 10 depends on the manufacturing method, when it is formed by etching from the contact layer 6 side, it is formed at least on the surface side of the contact layer 6 in contact with the first electrode 7, and this two-dimensional photonic crystal structure is active
- the wavelength of light that oscillates in the layer 3 is selected.
- FIG. 5A when viewed from the contact layer 6 side, the region where the recess 10 is formed has a strip shape. Of the light leaked from the active layer 3 and introduced into the two-dimensional photonic crystal structure, the light whose wavelength matches the periodic interval of the recesses 10 in the strip shape resonates.
- the two-dimensional photonic crystal surface emitting semiconductor laser which is the light source 70A described above, is one of grating-coupled surface emitting lasers and includes a two-dimensional photonic crystal structure in a preferable form as a grating (diffraction grating). Yes.
- the surface emitting laser laser light is emitted perpendicularly to the main surface of the element.
- the active layer 3 is parallel to the main surface and includes a diffraction grating. This diffraction grating simultaneously changes the traveling direction of light to approximately 180 ° and approximately 90 °.
- a laser resonator is formed by the approximately 180 ° conversion, and the light is vertically directed by the approximately 90 ° conversion. Is emitted.
- the two-dimensional photonic quasicrystal structure is a crystal structure having rotational symmetry without having the translational symmetry parallel to, for example, the x direction and the y direction described above.
- the first electrode 7 is made of a material that does not transmit light that resonates in a two-dimensional photonic crystal structure, and, as shown in FIG. It is formed so as to cover other parts except the end.
- the area of the recess 10 covered by the first electrode 7 is an area between the first electrode 7 and the second electrode 8 where laser oscillation occurs, and is referred to as a resonator area 51.
- carriers are injected into the active layer 3 by applying a voltage between the first electrode 7 and the second electrode 8, and the active layer 3 emits light at a voltage value equal to or higher than a predetermined value.
- the light generated in the active layer 3 leaks and is introduced into the two-dimensional photonic crystal structure and oscillates.
- the width Wp is preferably equal to or greater than the width of the coupler 29 so that the width (x direction) of the coupler 29 can be irradiated without shortage, and the length Lp stabilizes the laser oscillation and the oscillation wavelength. It is preferable to set the length or more.
- the light oscillated in the resonator region 51 can travel in the ⁇ y direction (first direction) in the two-dimensional photonic crystal structure and is not covered with the first electrode 7 (the two-dimensional photonic crystal structure is open).
- the light that has reached the region is emitted from the light emitting surface 53 to the outside as a coherent laser beam, and the light emitted in FIG.
- the region of the recess 10 that is not covered by the first electrode 7 and is open so that laser light can be emitted to the outside is called a surface emitting region 52, and the surface that is not covered by the first electrode 7 emits light.
- Surface 53 The region of the recess 10 that is not covered by the first electrode 7 and is open so that laser light can be emitted to the outside.
- the light traveling in the ⁇ y direction through the surface light emitting region 52 generates little light in the active layer 3 because there is almost no carrier injection into the active layer 3, and monotonous because diffraction in the + y direction occurs along with external diffraction. Decrease. For this reason, as the distance from the boundary between the first electrode 7 and the light emitting surface 53 (the boundary between the resonator region 51 and the surface light emitting region 52) moves in the direction of the light emitting surface 53 ( ⁇ y direction, direction of the surface light emitting region 52), The light intensity emitted to the outside decreases exponentially.
- the light intensity I emitted from the light emitting surface 53 has a maximum inclination near the boundary between the first electrode 7 and the light emitting surface 53, and a gradient that decreases toward the -y direction. It has an exponential function shape and has a thickness of width Wp in the x direction.
- This light intensity distribution is a suitable intensity distribution of light irradiated to the coupler 29 that is efficiently introduced into the waveguide 20A.
- the boundary between the light emitting surface 53 and the first electrode 7 is along a direction substantially perpendicular to the long side direction of the strip shape because the arrangement of the waveguide 20A and the light source 70A is easy.
- the light intensity distribution of the laser light emitted from the light source 70A is substantially similar to the light intensity distribution so that light is efficiently introduced into the waveguide 20A, and the light intensity distribution to the waveguide determined by the product of the overlapping portions of the two is obtained.
- the light introduction efficiency can be increased.
- a transparent electrode such as ITO (Indium Tin Oxide) may be provided on the light emitting surface 53 to increase the light intensity distribution of the laser light emitted from the light emitting surface 53 described above.
- ITO Indium Tin Oxide
- the surface light emitting region 52 becomes an absorption region because no current is injected, and the laser emission threshold increases. Therefore, in order to shorten the band gap of the surface light emitting region 52 and eliminate absorption loss, it is preferable to use quantum well disordering (QWI).
- QWI quantum well disordering
- the depths of the recesses 10 in the resonator region 51 and the surface light emitting region 52 may be different.
- the depth of the recess 10 in the resonator region 51 is as much as possible in the active layer so as to increase the optical coupling between the active layer 3 and the two-dimensional photonic crystal structure. 3 so that the bottom of the concave portion 10 approaches, and the depth of the concave portion 10 a of the surface light emitting region 52 is shallower than the concave portion 10 of the resonator region 51 and has a constant depth.
- the depth of the concave portion 10 b of the surface light emitting region 52 starts from the boundary between the first electrode 7 and the light emitting surface 53 and is closer to the light emitting surface 53 side from the boundary. You may make it shallow as it leaves
- the optical coupling efficiency is changed to adjust the reduction state from the maximum value of the light intensity I emitted from the light emitting surface 53, and the intensity distribution shape of the light emitted from the light emitting surface 53 irradiates the coupler 29. It can be adapted to the optimum shape of the light intensity distribution.
- the recess 10 shown in FIGS. 4 and 5B has a bottom immediately before reaching the active layer 3, and the depth of the recess 10 in the resonator region 51 and the surface emitting region 52 is the same.
- the position of the bottom of the concave portion 10 is not necessarily set immediately before reaching the active layer 3, and adverse effects such as damage to the active layer 3 when the concave portion 10 is formed, or optical coupling between the active layer 3 and the two-dimensional photonic crystal structure. What is necessary is just to determine suitably considering efficiency etc.
- the depth of the recess 10 is made different.
- the cross section in the depth direction may be constant such that 10 is cylindrical, and the cross sectional area may be changed.
- the refractive index of the material filling the recess 10 is smaller than the refractive index of the surrounding first cladding layer 5, the coupling efficiency can be increased by reducing the cross-sectional area.
- the depth and the cross-sectional area of the recess 10 are mentioned, but these may be used separately or in combination. .
- the photonic crystal structure of the surface light emitting region 52 may be arranged in parallel with the stripe groove-like recesses 10c as in the light source 70D shown in FIG. Since the photonic crystal structure of the resonator region 51 is two-dimensional, the laser light oscillates in a single mode, the width Wp is secured, and the laser light oscillated and amplified with this width Wp enters the surface emitting region 52.
- the laser light having the light intensity distribution as described above is emitted from the light emitting surface 53. 7 shows only the top view of the light source 70D, and the cross-sectional views thereof are the same as those in FIGS. 5B, 6A, and 6B, and are omitted, but the concave portion 10c of the surface light emitting region 52 is omitted.
- the depth may be the same as that of the resonator region 51 or may be shallow.
- the laser light incident on the coupler 29 of the waveguide 20 described so far is substantially perpendicular to the surface of the coupler 29, it may be required to be incident at a predetermined incident angle.
- the laser beam is tilted from a direction (normal line) perpendicular to the light emitting surface 53 to have an emission angle. Can be dealt with by injecting.
- the period of the surface emitting region 52 is made different from the period of the resonator region 51 in the two-dimensional photonic crystal structure.
- This example is shown in the light source 70E of FIGS. 8 (a) and 8 (b).
- 8A is a top view of the light source 70E
- FIG. 8B is a cross-sectional view taken along the line G-G ′ of FIG. 8A.
- the period of the recess 10 d in the x direction is the same as the period of the resonator region 51, and the period of the y direction is longer than the period of the resonator region 51.
- the cycle in the y direction in this manner, as shown in FIG. 8B, the laser light emitted from the light emitting surface 53 is changed to ⁇ 1st order diffracted light, and the emission angle in the yz plane is changed to + y. It can be deflected in two directions: the direction (light 50a-1) and the -y direction (light 50a-2).
- the period in the y direction may be appropriately changed so as to match the incident angle with respect to the coupler 29 of the waveguide 20.
- the period in the y direction of the recess 10d is longer than the period of the resonator region 51. It may be different and may be shortened. If the period of the recess 10d in the x direction is further changed, the emission angle in the zx plane can be changed, and the light emitted from the light emitting surface 53 is in the ⁇ x direction in addition to the ⁇ y direction described above. 4 directions.
- the arrangement of the concave portions 10d of the surface light emitting region 52 is a lattice point.
- the concave portions 10d of the surface light emitting region 52 are formed as stripe groove-shaped concave portions in the y direction.
- the period may be different from the period of the resonator region 51, and may be longer or shorter.
- FIG. 9A and 9B show an example in which a light source 70E that emits laser light inclined from a direction perpendicular to the light emitting surface 53 and the waveguide 20 are combined.
- FIG. 9A shows a combination of the waveguide 20B and the light source 70E that can efficiently introduce the laser light 50a-1 emitted downward ( ⁇ y direction) out of the two directions of laser light emitted from the light source 70E. Is shown. In this case, the laser beam 50a-2 is hardly introduced into the waveguide 20B.
- FIG. 9B shows a combination of the waveguide 20C and the light source 70E that can efficiently introduce the laser light 50a-2 emitted upward (+ y direction) out of the two directions of laser light emitted from the light source 70E. Show. In this case, the laser beam 50a-1 is hardly introduced into the waveguide 20B.
- the period in the y direction of the concave portion 10d of the surface light emitting region 52 is made different from that of the resonator region 51, so that the light emitting surface 53 can be viewed from the vertical direction.
- the tilted laser beams are emitted in two directions with almost equal intensities.
- one of the two laser beams emitted in two directions is not incident on the coupler 29 so as to be introduced into the waveguide 20, so that a loss occurs.
- the emission angle of the laser beam is tilted from the vertical direction with respect to the light emitting surface 53 so as to reduce this loss, the light intensity of one of the two directions emitted from the light source 70 is made stronger than the other.
- FIGS. 10 (a) and 10 (b) The specific example is shown in the light source 70F of FIGS. 10 (a) and 10 (b).
- 10A is a top view of the light source 70F
- FIG. 10B is a cross-sectional view taken along the line G-G ′ of FIG. 10A.
- FIG. 10B in the cross-sectional shape of the recess 10e on the yz plane (cross-sectional view taken along line GG ′), the y-direction of the recess 10e on the light emitting surface 53 side and the active layer 3 side is shown. So that the wedges have different widths and are asymmetrical with respect to the z-axis.
- the left side (+ y direction) boundary is substantially perpendicular to the main surface, but the right side ( ⁇ y direction) boundary is inclined clockwise toward the paper surface.
- the intensity of the ⁇ first-order diffracted light emitted from the light emitting surface 53 is inclined so that one is stronger than the other.
- the waveguide 20 to which the laser light is incident such as the waveguides 20B and 20C shown in FIG. Good.
- the light source 70F can introduce laser light into the waveguide 20B more efficiently than the light source 70E.
- any of the diffracted light in the upward direction (+ z direction) or the downward direction ( ⁇ z direction) One of them can be made larger than the other, and in the example of FIG. 10B, the light intensity in the + z direction becomes smaller than that in the ⁇ z direction.
- the cross-sectional shape (opening cross-sectional shape) perpendicular to the depth direction of the recess 10e is a triangle as shown in FIG. 10 (a), but is not limited to this, and is not limited to this. But you can.
- the photonic crystal structure of the surface light emitting region 52 has the depth of the concave portion 10 described so far, the stripe groove-shaped concave portion, y so that the laser light is efficiently introduced into the waveguide 20 to be irradiated with the laser light.
- Each of the change in direction period and the wedge shape of the cross-sectional shape of the recess may be used alone, or a plurality of them may be combined.
- the waveguide 20 and the light source 70 described so far are arranged and fixed so that the coupler 29 of the waveguide 20A and the light emitting surface 53 of the light source 70A face each other.
- the light 50 a emitted from the lower end portion of the light emitting surface 53 is preferably disposed so as to enter the lower end portion of the coupler 29. More specifically, the portion with the largest intensity distribution of the laser light emitted from the light emitting surface 53 is the light irradiation region of the coupler 29 where the light is introduced into the core layer 21, and the direction in which the light introduced into the core layer 21 travels. It is preferable to irradiate the front end of each of them.
- the waveguide 20 and the light source 70 can be fixed by, for example, an adhesive.
- an adhesive polyimide, UV curable resin, thermosetting resin, or the like that transmits light from the light source 70 can be used. It is not limited.
- the refractive index of the resin is preferably the same as or close to the refractive index of the material constituting the coupler 29 and the light emitting surface 53 from the viewpoint of reducing optical loss. Further, while the light from the light source 70 is introduced into the waveguide 20 through the adhesive, the refractive index and thickness of the adhesive may be adjusted so that the reflection of light is suppressed.
- the upper surface of the first cladding layer 5 is an emission surface (light emission surface 53) for emitting laser light, but the second electrode 8 side can also be an emission surface, A specific example is shown in the light source 70G of FIG.
- the substrate 1 is made of a material transparent to the wavelength band of the light to be extracted
- the first electrode 71 is formed on the contact layer 6 so as to cover the entire two-dimensional photonic crystal structure
- the second electrode 81 is opened. May be formed.
- an InGaAsP-based active layer (wavelength 1.3 ⁇ m to 1.5 ⁇ m) is an InP substrate
- an InGaAs active layer (wavelength 0.9 ⁇ m to 1.1 ⁇ m) is a GaAs substrate
- an InGaN active layer (wavelength 0.4 ⁇ m to 0.5 ⁇ m) is a GaN or sapphire substrate.
- the first electrode 71 and the second electrode 81 are made of a material such as gold that does not transmit the extracted light.
- the light source 70G can be described in the same manner as the light source 70A described with reference to FIGS.
- the second electrode 81 is a material that does not transmit light that resonates in the two-dimensional photonic crystal structure, and is formed so as to cover other portions except for the end portion on the short side of the strip shape of the two-dimensional photonic crystal structure. ing. Therefore, the region between the first electrode 71 and the second electrode 81 having a two-dimensional photonic crystal structure is the resonator region 51, which is not covered with the second electrode 81 and can emit laser light to the outside. Thus, the area
- a region that is not covered by the second electrode 81 at the end of the short side of the strip shape having a two-dimensional photonic crystal structure when viewed from the direction in which the laser light is emitted is a light emitting surface.
- a transparent electrode may be provided on the light emitting surface in the same manner as described for the light source 70A.
- the photonic crystal structure of the surface light emitting region 52 of the light source 70G has been described in the above-described modification of the depth of the recesses and the stripe grooves so that the laser light can be efficiently introduced into the waveguide to which the laser light is emitted.
- the concave portion, the change in the y-direction period, and the wedge shape of the cross-sectional shape of the concave portion may be introduced singly or in combination.
- the light source 70 described so far is a surface emitting semiconductor laser that includes the first electrode 7 and the second electrode 8 and emits laser light by current injection using these electrodes, but is a surface emitting semiconductor that emits laser light by light excitation instead of current injection. It can also be a laser.
- a surface-emitting semiconductor laser by optical excitation and an optical recording head equipped with this laser will be described.
- symbol is attached
- FIG. 13 conceptually shows, in section, the optical recording head 103 according to the present invention and its peripheral portion.
- the optical recording head 103 is an optical recording head that uses light for information recording on the disk 102, and includes a slider 30, a waveguide 20, a light source 80, a magnetic recording unit 35, a magnetic information reproducing unit 36, and the like.
- the light source 80 for introducing laser light into the waveguide 20 will be described below as a surface emitting semiconductor laser.
- a surface emitting semiconductor laser In addition to the semiconductor laser, an organic dye laser or a solid laser may be used. it can.
- a waveguide 20 and a light source 80 are provided on the side surface on the inflow side of the disk 102 that is substantially perpendicular to the recording surface of the disk 102.
- the light source 80 is a surface emitting semiconductor laser having a two-dimensional photonic crystal structure, similar to the light source 70, and irradiates the grating coupler with light so that the light is introduced into the waveguide 20.
- the light source 80 is a light excitation type that generates laser light when the light source 80 is irradiated with excitation light 110a from a light excitation source 110 that is another light source.
- the excitation light 110a is applied to the two-dimensional photonic crystal structure of the light source 80.
- the optical recording head 103 can be made small and thin.
- the light excitation source 110 emits light for irradiating the light source 80 to be optically excited.
- Examples of the light excitation source 110 include a semiconductor laser different from the light source 80 and an optical fiber emitting end.
- the optical excitation source 110 is a semiconductor laser, and substantially parallel light or convergent light so as to sufficiently irradiate the two-dimensional photonic crystal structure provided in the light source 80 with light emitted from the semiconductor laser.
- the optical excitation source 110 are fixed to the arm 105 together with a lens 112 having a plurality of lenses.
- Light emitted from the light source 80 is introduced into the waveguide 20, and the light introduced into the waveguide 20 travels to the lower end surface 24 of the waveguide 20 and is applied to the disk 102 as irradiation light for heating the disk 102. It is injected towards.
- the plasmon antenna 24d provided at or near the position where the light on the lower end surface 24 is emitted is omitted.
- the waveguide 20 of FIG. 13 shows the waveguides 20A to 20C of the specific examples described so far, and the light source 80 shows the light sources 80A to 80H of the specific examples described below, which are appropriately combined with these waveguides.
- FIG. 14 also shows the waveguide 20A and a light source 80A that emits light introduced into the waveguide 20A.
- the light 50a emitted from the light source 80A irradiates the coupler 29 of the waveguide 20A.
- the incident angle of the light that irradiates the coupler 29 may be substantially perpendicular to the waveguide 20 (incident angle is 0 °) or may have an incident angle as necessary.
- FIG. 14 shows an example in which the incident angle is 0 °.
- FIG. 15A is a top view of the light source 80A
- FIG. 15B is a cross-sectional view taken along the line G-G ′ of FIG.
- the light source 80A is formed on the substrate 1, the second cladding layer 2 formed on one main surface of the substrate 1, the active layer 3 formed on the second cladding layer 2, and the active layer 3.
- a semiconductor laminated portion having a first cladding layer 5 and a contact layer 6 and a two-dimensional photonic crystal structure that regulates the wavelength of laser light that is optically coupled to the active layer 3 to emit light are provided.
- a light source 80A provided on the slider 30 of the optical recording head 103 shown in FIG. 13 is irradiated with excitation light 110a emitted from the optical excitation source 110 arranged on the arm 105 from the substrate 1 side.
- the irradiated excitation light 110a passes through the substrate 1, is absorbed by the active layer 3 of the light source 80A, and electrons / hole pairs (carriers) are injected to generate light in the active layer 3, and light generated in the active layer 3 Is leaked into the two-dimensional photonic crystal structure and laser oscillation occurs, and the oscillated laser beam is emitted in the vertical direction from the light emitting surface 53 like light 50a.
- the light source 80A does not require external wiring for current injection, and Joule heat due to the resistance component of the semiconductor laser does not occur. Accordingly, the movement of the optical recording head 103 is not restricted by the wiring, and the optical recording head 103 is unlikely to be thermally deformed. Therefore, the optical recording head 103 can perform stable optical recording.
- the light emitting surface 53 shown in FIG. 15 is wide with respect to the coupler 29 as shown in FIG. 14, and the light 50a that does not irradiate the coupler 29 is lost, and there is also a possibility of affecting the outside. For this reason, it is preferable to cover a part of the light emitting surface 53 so as to shield the light that does not irradiate the coupler 29.
- the wavelength of the excitation light 110a emitted from the optical excitation source 110 may be any wavelength that the active layer 3 absorbs.
- the wavelength of the excitation light 110a is a laser of 780 nm or the like. Any wavelength shorter than the oscillation wavelength of 980 nm may be used.
- the substrate 1 since the excitation light 110a is irradiated from the substrate 1, the substrate 1 needs to be transparent to the excitation light 110a.
- the excitation light 110a needs to have a wavelength that is longer than 870 nm and shorter than 980 nm as described above because the wavelength needs to be transmitted through the GaAs substrate. It is.
- the configuration of the light source 80 is substantially the same as that of the light source 70, but the main points that are different from the light source 70 in relation to the light excitation will be described below.
- the active layer 3 needs to consider the following in addition to the description of the light source 70.
- a material system having a wavelength longer than that of the substrate 1 for example, an InGaAsP active layer on an InP substrate: wavelength 1.3 ⁇ m to 1.5 ⁇ m, an InGaAs active layer on a GaAs substrate: wavelength 0.9 ⁇ m to 1.1 ⁇ m
- the substrate 1 is transparent to the emission wavelength (also an absorption wavelength) of the active layer 3.
- the light source 80A shown in FIGS. 14 and 15 can make the excitation light 110a incident from the substrate 1 side.
- the contact layer 6 is provided, but it is not necessary to provide it because it is photoexcited.
- the region where the recess 10 is formed is a strip shape having a width Wp and a length Lp1.
- the width Wp the light emitting region can have a width.
- the width Wp is the width of the coupler 29 (x direction).
- the length Lp1 is preferably equal to or longer than the length at which the laser oscillation and the oscillation wavelength are stable.
- light that leaks from the active layer 3 and is introduced into the two-dimensional photonic crystal structure resonates and is amplified by light whose wavelength matches the period interval of the recesses 10 in the strip shape. Oscillated and emitted as a coherent laser beam in the vertical direction from the light emitting surface 53 of the strip-shaped region.
- laser light generated by light excitation is emitted in a substantially vertical direction from the strip-shaped light emitting surface 53 by the two-dimensional photonic crystal structure provided by forming the recess 10 in the first cladding layer 5. Then, the light is introduced into the waveguide 20A through the irradiating coupler 29.
- the excitation light 110a irradiates a region excluding a region where the light that irradiates the coupler 29 is emitted in the region of the two-dimensional photonic crystal structure.
- the excitation light 110a is irradiated on the region where the light that irradiates the coupler 29 is emitted, a part of the excitation light 110a enters the coupler 29, which may cause noise.
- FIG. 14 shows a region where the excitation light 110 a irradiates the two-dimensional photonic crystal structure as a resonator region 51 and a region where the light emitted from the coupler 29 is emitted as a surface emitting region 52.
- the light source 80A satisfactorily oscillates a laser beam having a constant wavelength without being affected even if the wavelength of the excitation light 110a fluctuates due to a change in operating environment temperature such as a mode hop phenomenon that occurs in a Fabry-Perot laser. be able to. Further, the light source 80A can satisfactorily oscillate when an approximate region where the photonic crystal is formed is irradiated with the excitation light 110a. For this reason, even if the positional deviation or the incident angle of the excitation light 110a that irradiates the light source 80A changes, the light source 80A can oscillate well with almost no influence.
- the irradiation position, the incident angle, and the wavelength when the excitation light 110a irradiates the light source 80A have a wider error tolerance range than the case where the light source 80A irradiates the coupler 29 provided in the waveguide 20.
- the optical recording head 103 of FIG. 13 when the slider 30 is provided with the waveguide 20A and the light source 80A and integrated, the positional relationship between the optical excitation source 110 and the optical recording head 103 can be easily adjusted. Can do. Further, in the actual optical recording operation, it is possible to prevent the positional deviation exceeding the allowable error from easily occurring in the above-described positional relationship. Therefore, the optical recording head 103 can perform stable optical recording.
- a lens 112 is disposed as a condensing lens in the optical path to condense the excitation light 110a.
- a curved surface or a diffraction grating is formed on the substrate 1 of FIG. It may be.
- the light source 80B in which the light intensity distribution of the laser light emitted from the light source 80 is introduced into the core layer 21 from the coupler 29 efficiently in the same manner as the light source 70 will be described below.
- FIG. 16 (a) is a top view of the light source 80B
- FIG. 16 (b) is a cross-sectional view taken along line G-G ′ of FIG. 5 (a).
- the light source 80B is formed on the substrate 1, the second cladding layer 2 formed on one main surface of the substrate 1, the active layer 3 formed on the second cladding layer 2, and the active layer 3.
- a semiconductor laminate having a first cladding layer 5 and a contact layer 6 and a light shielding member 9 formed on the contact layer 6 are provided.
- the light shielding member 9 is provided so as to cover a part of the concave portion 10 forming a two-dimensional photonic crystal structure.
- the light shielding member 9 is made of a material that does not transmit light that resonates in a two-dimensional photonic crystal structure. As shown in FIG. 16A, one of the short sides of the strip-shaped side of the region where the recess 10 is formed. It is formed so as to cover other parts except the end.
- the region of the recess 10 covered by the light shielding member 9 is a resonator region 51 that is preferably irradiated with excitation light 110a and oscillates.
- the position where the excitation light 110 a irradiates the resonator region 51 is the surface on the opposite side of the light shielding member 9 of the substrate 1, but is not limited to this, and the side surface side (x direction side) However, as long as the excitation light 110a can be transmitted, the light shielding member 9 may be used. That is, the position irradiated with the excitation light 110 a may be anywhere around the resonator region 51.
- electron / hole pairs (carriers) generated by the excitation light 110 a incident through the substrate 1 are injected into the active layer 3, and light is generated in the active layer 3, and is generated in the active layer 3.
- the leaked light is leaked and introduced into the two-dimensional photonic crystal structure and oscillates.
- the width Wp is preferably equal to or greater than the width of the coupler 29 so that the width (x direction) of the coupler 29 can be irradiated without shortage, and the length Lp stabilizes the laser oscillation and the oscillation wavelength. It is preferable to set the length or more.
- the light oscillated in the resonator region 51 can travel in the ⁇ y direction (first direction) in the two-dimensional photonic crystal structure and is not covered with the light shielding member 9 (the two-dimensional photonic crystal structure is released).
- the light reaching the region is emitted from the light emitting surface 53 to the outside as coherent laser light.
- FIG. 16B shows laser light emitted from the light emitting surface 53 to the outside as light 50a.
- the region of the recess 10 that is not covered by the light shielding member 9 and is open so that laser light can be emitted to the outside is a surface light emitting region 52, and the surface not covered by the light shielding member 9 is a light emitting surface 53. It is.
- the light traveling in the ⁇ y direction through the surface light emitting region 52 is not irradiated with the excitation light 110a and does not generate photoexcitation, so that the light generated in the active layer 3 is small, and the diffraction in the + y direction is generated together with the outward diffraction. Decrease. For this reason, as the distance from the boundary between the light shielding member 9 and the light emitting surface 53 (the boundary between the resonator region 51 and the surface light emitting region 52) moves in the direction of the light emitting surface 53 ( ⁇ y direction, direction of the surface light emitting region 52), The intensity of the light emitted to the power decreases exponentially.
- the light intensity I emitted from the light emitting surface 53 is maximum near the boundary between the light shielding member 9 and the light emitting surface 53, and the slope that decreases toward the ⁇ y direction is an exponential value. It has a function shape and has a thickness of width Wp in the x direction. Similar to the light source 70, this light intensity distribution is a suitable intensity distribution of light irradiated on the coupler 29 that is efficiently introduced into the waveguide 20.
- the depths of the recesses 10 in the resonator region 51 and the surface light emitting region 52 may be different. This is the same as the light sources 70B and 70C in FIGS.
- the photonic crystal structure of the surface light emitting region 52 may be arranged in parallel with stripe groove-like recesses 10c as in the light source 80E shown in FIG. This is the same as the light source 70D of FIG.
- the laser beam is emitted with an emission angle inclined from a direction (normal line) perpendicular to the light emitting surface 53. In this way, it can respond.
- the period of the surface emitting region 52 is made different from the period of the resonator region 51 in the two-dimensional photonic crystal structure.
- This example is shown in the light source 80F of FIGS. 19 (a) and 19 (b).
- 19A is a top view of the light source 80F
- FIG. 19B is a cross-sectional view taken along the line G-G ′ of FIG. 19A. This is the same as the light source 70E shown in FIGS.
- 20A and 20B show an example of a combination of a light source 80F that emits laser light inclined from the normal line of the light emitting surface 53 and the waveguide 20. Since this is the same as the content described in combination with the light source 70E and the waveguides 20B and 20C in FIG. 9, the description is omitted.
- FIGS. 20A and 20B one of the laser beams emitted in two directions is not incident on the coupler 29 so as to be introduced into the waveguide 20, resulting in a loss.
- the emission angle of the laser beam is tilted from the direction perpendicular to the light emitting surface 53 so as to reduce this loss, the light intensity of one of the two directions emitted from the light source 80 is made stronger than the other.
- FIG. 21A is a top view of the light source 80G
- FIG. 21B is a cross-sectional view taken along line G-G ′ of FIG. This is the same as the light source 70F in FIGS. 10A and 10B, and a description thereof will be omitted.
- the photonic crystal structure of the surface light emitting region 52 in the light source 80 has a depth of the recess 10 so that the laser light can be efficiently introduced into the waveguide 20 to be irradiated with the laser light.
- Each of the stripe groove-shaped concave portion, the period change in the y direction, and the wedge shape of the cross-sectional shape of the concave portion may be used alone, or a plurality of them may be combined.
- the excitation light 110a cannot pass through the substrate 1
- the emission wavelength of the active layer 3 is, for example, 980 nm and the wavelength of the excitation light 110a is 780 nm
- the GaAs substrate is opaque and cannot be excited by light irradiation from the substrate 1 side as described above.
- the light source 80H shown in FIG. 22 is configured.
- the light source 80H shown in FIG. 22 can be described in the same manner as the light source 80B described with reference to FIGS.
- the light shielding member 9 forms a two-dimensional photonic crystal structure on the surface of the substrate 1 opposite to the side on which the second cladding layer 2 is formed as viewed from the direction in which the laser light 50a-5 of the substrate 1 is emitted. It forms so that the other part except the edge part of the short side of the strip shape of the area
- the region of the recess 10 covered by the light shielding member 9 is preferably a region irradiated with the excitation light 110a, and is a resonator region 51 that oscillates.
- a region of the recess 10 that is not covered by the light shielding member 9 and is open so that laser light can be emitted to the outside is a surface light emitting region 52, and the substrate 1 is a light emitting surface 53.
- the light source 80H is optically excited by being irradiated with excitation light 110a having a wavelength of 780 nm from the first cladding layer 5 side, and the oscillated laser light having a wavelength of 980 nm passes through the GaAs substrate 1 that can transmit at the wavelength of 980 nm to the waveguide 20A. Irradiated and introduced.
- the photonic crystal structure of the surface light emitting region 52 has a recess depth change, stripe groove shape, and so on so that the laser light is efficiently introduced into the waveguide to which the laser light is emitted.
- Each of the recesses, the period change in the y direction and the wedge shape of the cross-sectional shape of the recesses may be introduced independently, or a plurality may be introduced in combination.
- a semiconductor laser using a group III-V semiconductor is taken as an example of the material of the semiconductor stacked portion, but it is also possible to use an organic light emitting material and a solid dye material instead.
- a laser (organic dye laser) having a two-dimensional photonic crystal structure by forming a two-dimensional photonic crystal structure on a quartz substrate surface and depositing an organic light emitting material thereon by spin coating or vapor deposition can do.
- a two-dimensional photonic crystal structure is formed on the surface of the quartz substrate, and upper and lower cladding layers are formed by forming a film thereon by sputtering, and a two-dimensional photonic is formed by forming a solid dye between the upper and lower cladding layers.
- a laser (organic dye laser) having a crystal structure can be obtained.
- the embodiment described above relates to an optically assisted magnetic recording head and an optically assisted magnetic recording apparatus.
- the main configuration of the embodiment is an optical recording head in which a recording medium is an optical recording disk, It can also be used for an optical recording apparatus. In this case, the magnetic recording unit 35 and the magnetic information reproducing unit 36 provided on the slider 30 are unnecessary.
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Abstract
Description
回折格子を介して結合された前記光源からの光を記録媒体に照射する導波路と、を少なくとも有し、
前記光源は、
前記導波路と対向する側の面に2次元フォトニック結晶構造を有し、
前記2次元フォトニック結晶構造は、前記回折格子と対向する領域を除く領域が被覆されて、前記回折格子と対向する領域を面発光領域とする面発光レーザであることを特徴とする光記録ヘッド。
前記励起光は、前記面発光領域を照射しないことを特徴とする前記3に記載の光記録ヘッド。
少なくとも前記光源、前記導波路及び磁気記録部を備え、前記磁気記録媒体に対して相対移動するスライダを有することを特徴とする前記1から5の何れか一項に記載の光記録ヘッド。
第1クラッド層と、第2クラッド層と、前記第1クラッド層と前記第2クラッド層とにより挟まれキャリア注入により所定の波長の光を発生する活性層と、を有する半導体積層部と、
前記第1クラッド層に接続される第1電極と、
前記第2クラッド層に接続される第2電極と、を備え、
前記第1クラッド層は、屈折率が面内方向に前記所定の波長に対応する周期で変化し、前記活性層と光学的に結合して該活性層で発生した光が導入され、導入された前記所定の波長の光が回折されてレーザ発振し、少なくとも一部の光の進行方向を前記面内方向に対し垂直方向に転換するように構成されている回折格子を有し、
前記回折格子は、前記グレーティングカプラと対向する領域を除く領域が被覆されて、前記グレーティングカプラと対向し、前記垂直方向に転換された光を射出する領域を面発光領域とし、
前記回折格子を被覆する部材が前記第1電極であり、該第1電極に対向する前記第2電極とでレーザ発振する共振器領域が形成されていることを特徴とする面発光半導体レーザ。
前記面発光領域から射出される光の光強度分布は、前記共振器領域から前記面発光領域へ向かう第1方向において、前記共振器領域と前記面発光領域との境界の近傍で最大であり、前記境界から前記面発光領域の方向へ離れるに従って減少することを特徴とする前記7に記載の面発光半導体レーザ。
前記面発光領域の前記凹部は、前記第1方向に垂直な方向に沿ったストライプ溝状の凹部であって、前記第1方向の周期が前記正方格子の周期と同じ周期で配置されていることを特徴とする前記10に記載の面発光半導体レーザ。
前記面発光領域の前記穴状の凹部は、前記第1方向に垂直な方向の周期が前記共振器領域の前記正方格子の周期と同じで、前記第1方向の周期が前記正方格子の周期と異なる周期で配置されていることを特徴とする前記10に記載の面発光半導体レーザ。
前記面発光領域の前記凹部は、前記第1方向に垂直な方向に沿ったストライプ溝状の凹部であって、前記第1方向の周期が前記正方格子の周期と異なる周期で配置されていることを特徴とする前記10に記載の面発光半導体レーザ。
前記面発光領域の前記凹部は、前記主平面からの深さが深くなるに従って、前記第1方向の前記凹部の幅が小さくなる又は大きくなり、且つ、前記主平面に対して垂直な軸に対して非対称であることを特徴とする前記13又は14に記載の面発光半導体レーザ。
前記7から19の何れか一項に記載の面発光半導体レーザと、
前記記録媒体に対して相対移動するスライダと、
前記記録媒体の記録面に略垂直な前記スライダの側面に、前記面発光半導体レーザにより照射される光が導入され、導入された光を前記記録媒体に向けて伝搬する前記導波路と、を備えていることを特徴とする光記録ヘッド。
前記記録媒体と、を備えていることを特徴とする光記録装置。
(1)記録用のディスク(記録媒体)102
(2)支軸106を支点として矢印Aの方向(トラッキング方向)に回転可能に設けられたアーム105に支持されたサスペンション104
(3)アーム105に取り付けられ、アーム105を回転駆動するトラッキング用アクチュエータ107
(4)サスペンション104及びその先端部に結合部材104aを介して取り付けられているスライダ30を含む光アシスト式磁気記録ヘッド(以下、光記録ヘッド103と称する。)
(5)ディスク102を矢印Bの方向に回転させるモータ(図示しない)
(6)トラッキング用アクチュエータ107、モータ及びディスク102に記録するために書き込み情報に応じて照射する光、磁界の発生等の光記録ヘッド103を用いてディスク102に光記録を行う制御を行う制御部108
光記録装置100おいては、スライダ30がディスク102上で浮上しながら相対的に移動しうるように構成されている。
2 第2クラッド層
3 活性層
5 第1クラッド層
6 コンタクト層
7、71 第1電極
8、81 第2電極
9 遮光部材
10、10a、10b、10c、10d、10e 凹部
20、20A、20B、20C 導波路
21 コア層
22 下クラッド層
23 上クラッド層
24 下端面
24d プラズモンアンテナ
26、27 側面
29 カプラ
30 スライダ
50a、50a-1、50a-2、50a-3、50a-4、50a-5 光
51 共振器領域
52 面発光領域
53 発光面
70、70A~70G、80、80A~80H 光源
100 光記録装置
101 筐体
102 ディスク
103 光記録ヘッド
104 サスペンション
105 アーム
110 光励起源
110a 励起光
Wp 幅
Lp、Lp1 長さ
Claims (22)
- 光源と、
回折格子を介して結合された前記光源からの光を記録媒体に照射する導波路と、を少なくとも有し、
前記光源は、
前記導波路と対向する側の面に2次元フォトニック結晶構造を有し、
前記2次元フォトニック結晶構造は、前記回折格子と対向する領域を除く領域が被覆されて、前記回折格子と対向する領域を面発光領域とする面発光レーザであることを特徴とする光記録ヘッド。 - 前記面発光レーザは、前記2次元フォトニック結晶構造を被覆する部材が第1の電極であり、該第1の電極に対向する第2の電極とで共振器領域を形成する面発光半導体レーザであることを特徴とする請求項1に記載の光記録ヘッド。
- 前記面発光レーザは、前記2次元フォトニック結晶構造を被覆する部材が遮光部材であり、前記面発光レーザの遮光部材がある側の反対側に照射される励起光にて発光することを特徴とする請求項1に記載の光記録ヘッド。
- 前記光源は、前記導波路に固定されていることを特徴とする請求項1から3の何れか一項に記載の光記録ヘッド。
- 前記面発光レーザを発光させる励起光を発する光励起源を有し、
前記励起光は、前記面発光領域を照射しないことを特徴とする請求項3に記載の光記録ヘッド。 - 前記記録媒体は、磁気記録媒体であり、
少なくとも前記光源、前記導波路及び磁気記録部を備え、前記磁気記録媒体に対して相対移動するスライダを有することを特徴とする請求項1から5の何れか一項に記載の光記録ヘッド。 - グレーティングカプラを有する導波路に対向して配置され、該導波路に導入する光を前記グレーティングカプラに対して射出する面発光半導体レーザであって、
第1クラッド層と、第2クラッド層と、前記第1クラッド層と前記第2クラッド層とにより挟まれキャリア注入により所定の波長の光を発生する活性層と、を有する半導体積層部と、
前記第1クラッド層に接続される第1電極と、
前記第2クラッド層に接続される第2電極と、を備え、
前記第1クラッド層は、屈折率が面内方向に前記所定の波長に対応する周期で変化し、前記活性層と光学的に結合して該活性層で発生した光が導入され、導入された前記所定の波長の光が回折されてレーザ発振し、少なくとも一部の光の進行方向を前記面内方向に対し垂直方向に転換するように構成されている回折格子を有し、
前記回折格子は、前記グレーティングカプラと対向する領域を除く領域が被覆されて、前記グレーティングカプラと対向し、前記垂直方向に転換された光を射出する領域を面発光領域とし、
前記回折格子を被覆する部材が前記第1電極であり、該第1電極に対向する前記第2電極とでレーザ発振する共振器領域が形成されていることを特徴とする面発光半導体レーザ。 - 前記面発光領域は、前記回折格子の端部に設けられ、
前記面発光領域から射出される光の光強度分布は、前記共振器領域から前記面発光領域へ向かう第1方向において、前記共振器領域と前記面発光領域との境界の近傍で最大であり、前記境界から前記面発光領域の方向へ離れるに従って減少することを特徴とする請求項7に記載の面発光半導体レーザ。 - 前記面発光領域から光が射出される側から見た前記回折格子が設けられている領域は、前記第1方向を長辺とする短冊形状であることを特徴とする請求項8に記載の面発光半導体レーザ。
- 前記回折格子は、前記第1クラッド層に前記周期を持って配置された凹部に、前記第1クラッド層の物質の屈折率と異なる屈折率の物質が充填されていることを特徴とする請求項8又は9に記載の面発光半導体レーザ。
- 前記凹部は穴状の凹部であって、前記共振器領域及び前記面発光領域の前記穴状の凹部は、前記第1方向及び該第1方向に垂直な方向に沿って正方格子に配置されていることを特徴とする請求項10に記載の面発光半導体レーザ。
- 前記共振器領域の前記凹部は、前記第1方向及び該第1方向に垂直な方向に沿って正方格子に配置された穴状の凹部であり、
前記面発光領域の前記凹部は、前記第1方向に垂直な方向に沿ったストライプ溝状の凹部であって、前記第1方向の周期が前記正方格子の周期と同じ周期で配置されていることを特徴とする請求項10に記載の面発光半導体レーザ。 - 前記凹部は穴状の凹部であって、前記共振器領域の前記穴状の凹部は、前記第1方向及び該第1方向に垂直な方向に沿って正方格子に配置され、
前記面発光領域の前記穴状の凹部は、前記第1方向に垂直な方向の周期が前記共振器領域の前記正方格子の周期と同じで、前記第1方向の周期が前記正方格子の周期と異なる周期で配置されていることを特徴とする請求項10に記載の面発光半導体レーザ。 - 前記共振器領域の前記凹部は、前記第1方向及び該第1方向に垂直な方向に沿って正方格子に配置された穴状の凹部であり、
前記面発光領域の前記凹部は、前記第1方向に垂直な方向に沿ったストライプ溝状の凹部であって、前記第1方向の周期が前記正方格子の周期と異なる周期で配置されていることを特徴とする請求項10に面発光半導体レーザ。 - 前記第1方向で、且つ、前記第1クラッド層の前記活性層に対する面と反対側の主平面に垂直方向の前記凹部の断面において、
前記面発光領域の前記凹部は、前記主平面からの深さが深くなるに従って、前記第1方向の前記凹部の幅が小さくなる又は大きくなり、且つ、前記主平面に対して垂直な軸に対して非対称であることを特徴とする請求項13又は14に記載の面発光半導体レーザ。 - 前記第1クラッド層の前記活性層に対する面と反対側の主平面からの前記凹部の深さ方向の断面が同じであって、前記共振器領域での前記凹部の断面積と前記面発光領域での前記凹部の断面積とは異なることを特徴とする請求項11又は13に記載の面発光半導体レーザ。
- 前記第1クラッド層の前記活性層に対する面と反対側の主平面からの前記凹部の深さは、前記共振器領域と前記面発光領域とで異なることを特徴とする請求項10から16の何れか一項に記載の面発光半導体レーザ。
- 前記面発光領域における前記凹部の深さは、前記境界の近傍より前記境界より離れる方向の前記面発光領域の端部の方が浅いことを特徴とする請求項17に記載の面発光半導体レーザ。
- 前記第1方向に垂直な方向の前記回折格子がある領域の幅は、光が照射される前記グレーティングカプラの幅以上であることを特徴とする請求項8から18の何れか一項に記載の面発光半導体レーザ。
- 記録媒体に光を用いて情報記録を行う光記録ヘッドにおいて、
請求項7から19の何れか一項に記載の面発光半導体レーザと、
前記記録媒体に対して相対移動するスライダと、
前記記録媒体の記録面に略垂直な前記スライダの側面に、前記面発光半導体レーザにより照射される光が導入され、導入された光を前記記録媒体に向けて伝搬する前記導波路と、を備えていることを特徴とする光記録ヘッド。 - 前記面発光半導体レーザは、前記導波路に固定されていることを特徴とする請求項20に記載の光記録ヘッド。
- 請求項20又は21に記載の光記録ヘッドと、
前記記録媒体と、を備えていることを特徴とする光記録装置。
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US13/375,407 US20120072931A1 (en) | 2009-06-05 | 2010-03-05 | Surface emitting semiconductor laser, optical recording head, and optical recording apparatus |
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