WO2004073125A1 - 半導体レーザ素子、光学ヘッド、及び情報記録装置 - Google Patents
半導体レーザ素子、光学ヘッド、及び情報記録装置 Download PDFInfo
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- WO2004073125A1 WO2004073125A1 PCT/JP2004/001037 JP2004001037W WO2004073125A1 WO 2004073125 A1 WO2004073125 A1 WO 2004073125A1 JP 2004001037 W JP2004001037 W JP 2004001037W WO 2004073125 A1 WO2004073125 A1 WO 2004073125A1
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- laser device
- refractive index
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
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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
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
- H01S5/227—Buried mesa structure ; Striped active layer
-
- 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
- H01S5/30—Structure or shape of the active region; Materials used for the active region
- H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
- H01S5/341—Structures having reduced dimensionality, e.g. quantum wires
Definitions
- the present invention relates to a semiconductor laser device. Further, the present invention relates to an optical head and an information recording device equipped with a semiconductor laser element.
- an A1GaAs-based infrared semiconductor laser device which is used as a pickup light source for an optical head for a compact disk (CD), has a horizontal transverse mode stability.
- those having a buried hetero type waveguide structure are known (for example, KAZUTOSHI SAIT0 et al., “Buried-Heterostructure AlGaAs Lasers) J, (USA), I ⁇ Trifino Rei-Janano Reservoir 'Electronitas (IEEE Journal of
- this semiconductor laser device generated laser oscillation at a wavelength of 0.812 ⁇ m.
- the full width at half maximum of the light intensity distribution of the near-field image of the laser element 900 during laser oscillation is 0.78 / im in the parallel direction, 0.25 m in the vertical direction, and The shape is elliptical.
- the spread angle of the far-field image is 24 degrees in the parallel direction and 37 degrees in the vertical direction.
- the laser light emitted from the semiconductor laser element spreads in space at a certain angle (far-field image), so that in a normal pickup, the laser light emitted from the semiconductor laser element is transmitted to a recording medium via a lens system. It is focused.
- blue semiconductor laser devices that can reduce the spot size compared to infrared semiconductor laser devices are being developed, and a blue semiconductor laser device with a wavelength of 405 nm and NA (numerical aperture) are being developed.
- technology for mass production of GaN-based materials for blue semiconductor laser devices has not been established, and the reliability of blue semiconductor laser devices cannot be said to be sufficient. .
- the distance between the light source and the recording medium is set to a very small distance (several tens to several hundreds of nm), and the near-field is not passed through the lens system.
- An optical memory that performs recording using light has been proposed (for example, Fumio Koyama et al., "Near-field light generation by surface emitting laser", Japan Society of Applied Physics, Japan Society of Applied Physics, Vol. 68, No. 12) No., 1989, pp. 138 0—1383. In this way, the distance between the light source and the recording medium is less than 1 am, not through the lens system.
- the method is called “proximity recording method.”)
- a surface emitting laser having a metal aperture having a small aperture of about several tens to several hundreds of nm at an emission end is used.
- Such a proximity recording method can obtain a light spot of a minute size exceeding the diffraction limit of light, and can obtain a light spot smaller than a high-density optical disk using a blue semiconductor laser device. It has the potential to realize higher density optical memory. However, there is a problem that the light output is very weak because the light use efficiency is extremely low. Disclosure of the invention
- an object of the present invention is to obtain a light spot smaller than that of a blue semiconductor laser device while using an existing compound semiconductor material, and to provide a light spot smaller than a semiconductor laser device having a metal aperture used for a proximity recording method.
- Another object of the present invention is to provide a semiconductor laser device which can obtain a minute light spot (near-field image) with a light output sufficient for practical use and is easily configured.
- a semiconductor laser device has a resonator having a high refractive index portion extending in one direction with a cross section of a certain shape, and a low refractive index portion surrounding the high refractive index portion.
- the dimension of the cross section of the high refractive index portion is set to a value such that the area of the near-field image of the laser beam emitted from the resonator is minimized or is set to a value close to the value. I do.
- One direction in which the high refractive index portion extends means the direction of the cavity length of the semiconductor laser device.
- the dimension of the cross section of the high refractive index portion is set to a value such that the area of the near-field image of the laser light emitted from the resonator is minimized, or to a value close to the value.
- the semiconductor laser device of the present invention is preferably applied to an optical system using a small spot, for example, an optical system of a proximity recording system. Further, the semiconductor laser device of the present invention can be easily configured simply by appropriately setting the cross-sectional dimensions of the high refractive index portion with respect to the conventional semiconductor laser device.
- Each of the high refractive index portion and the low refractive index portion may be made of a plurality of types of materials.
- the cross-sectional shape of the high refractive index portion is desirably triangular, rectangular, trapezoidal, regular polygonal, or circular. If the cross section of the high refractive index portion has a triangular, rectangular, or trapezoidal shape, it can be easily manufactured using a known manufacturing process.
- the area of the near-field image is smaller if it is a regular polygon, and the area of the near-field image is smallest if it is circular.
- the thickness D and the lateral width W of the cross section of the high refractive index portion are such that the dimensions of the myopic field image of the laser light emitted from the resonator in the thickness direction and the lateral direction are respectively It is desirable that the value be set to a value at which the minimum value is obtained or in the vicinity of the value.
- this semiconductor laser device has a resonator having a high refractive index portion extending in one direction with a cross section of a certain shape, and a low refractive index portion surrounding the high refractive index portion.
- the thickness D and the width W of the cross section of the high refractive index portion are such that the dimensions of the near-field image of the laser beam emitted from the resonator are minimized in the thickness direction and the lateral direction, respectively. It is characterized in that it is set at or near the value.
- the “thickness” D of the cross section of the high refractive index portion refers to the dimension in the laminating (deposition) direction of the semiconductor layer constituting the high refractive index portion within the cross section.
- the “width” W of the cross section of the high refractive index portion indicates a dimension in a direction perpendicular to the laminating direction in the cross section.
- the “thickness direction” and “lateral direction” refer to directions along the “thickness” D and the “width” W of the high refractive index portion, respectively.
- the thickness D and the lateral width W of the cross section of the high refractive index portion are such that the dimensions of the near-field image of the laser light emitted from the resonator are minimized in the thickness direction and the lateral direction. Is set at or near such a value.
- a minute light spot can be obtained with a light output sufficient for practical use as compared with a conventional semiconductor laser device having a metal aperture used for the proximity recording method (described later).
- the semiconductor laser device of the present invention is preferably applied to an optical system using a minute spot, for example, an optical system of a proximity recording system. Further, the semiconductor laser device of the present invention can be easily configured simply by appropriately setting the cross-sectional dimensions of the high refractive index portion with respect to the conventional semiconductor laser device.
- the high refractive index portion respectively the refractive index of the low refractive index portion n a, represents a n c, the difference delta n r of their refractive index
- the thickness D and width W of the cross section of the high refractive index portion are respectively
- the unit of D and IW is ⁇ , and the unit of ⁇ is nm. It is desirable to satisfy the following relationship.
- An r is a representation of a percentage ratio against the n c of the (n a -n c), it is dimensionless.
- a resonator having a high refractive index portion extending in one direction with a cross section of a certain shape, and a low refractive index portion surrounding the high refractive index portion;
- the thickness D and width W of the cross section of the high refractive index portion are respectively
- the thickness D and the width W of the high refractive index portion have the same value. It is desirable that the high refractive index portion is a light emitting layer.
- the “quantum well structure” may be made of parc, or may have quantum wires or quantum boxes.
- the low refractive index portion be made of Al x Ga 1 -x As (where 0 ⁇ x ⁇ 1).
- the high refractive index portion contains nitrogen and a group V element other than nitrogen in its composition.
- a semiconductor laser device of the present invention includes a resonator that extends in one direction parallel to a surface of a substrate and emits laser light from an end face, on the substrate, and a laser light near the laser light.
- the full width at half maximum of the light intensity distribution of the visual field image in the vertical direction and the parallel direction to the substrate surface is 0.28 / im or less.
- the full width at half maximum of the light intensity distribution in the vertical direction and the full width at half maximum of the light intensity distribution in the parallel direction of the near-field image have the same value.
- the low-refractive-index portion includes a p-type region and an n-type region separated from each other by a boundary surface extending along the one direction, and the high-refractive-index portion includes the low-refractive-index portion. It is desirable that it is sandwiched between the above-mentioned!) Type region and the n-type region.
- Type region means a region showing a p-type conductivity type
- n-type region means a region showing an n-type conductivity type.
- the semiconductor laser device of this embodiment by applying a positive potential and a negative potential to the p-type region and the n-type region, respectively, a current can easily flow through the high refractive index portion. Therefore, laser oscillation can be performed with the high refractive index portion functioning as an active layer.
- an insulator layer is interposed along the boundary between the p-type region and the n-type region of the low refractive index portion around the high refractive index portion. Is desirable.
- an insulator layer is provided along a boundary surface between the p-type region and the n-type region of the low refractive index portion, which corresponds to both sides of the high refractive index portion. Since it is inserted, the current flow is interrupted by the insulator layer. Therefore, the current flows intensively through the high refractive index portion, and the efficiency of current injection into the high refractive index portion is improved. Therefore, the electrical characteristics of the semiconductor laser device are improved.
- the insulator layer is made of aluminum oxide.
- the resistance of the aluminum oxide is high, current injection into the high refractive index portion can be performed very efficiently.
- oxide Arumyeu beam includes not only A l 2 ⁇ 3, A 1 0 x (X is O composition ratio of for A 1) widely includes those represented by.
- the aluminum oxide It is desirable that the aluminum be formed by thermally oxidizing aluminum. In such a case, aluminum oxide aluminum is easily manufactured.
- "hidani aluminum” is represented by A1As.
- An optical head according to the present invention is an optical head for recording or reproducing information on or from a recording medium by using the laser light emitted from the semiconductor laser element, in cooperation with the above-described semiconductor laser element.
- an optical spot (near-field image) smaller than that obtained by a conventional blue semiconductor laser element can be obtained on a recording medium by the laser light emitted from the semiconductor laser element. it can.
- information can be recorded or reproduced with a light output larger than that of a semiconductor laser device having a metal aperture used in the proximity recording method.
- the distance between the light emitting end face of the semiconductor laser device and the recording medium is close to less than 1.am.
- the semiconductor laser element and the recording medium are arranged such that a distance between the light emitting end face of the semiconductor laser element and the recording medium is close to less than 1 ⁇ m. It is characterized by having a control mechanism for controlling the distance between.
- An information recording device is an information recording device including the above-described semiconductor laser device.
- the above-described semiconductor laser device is used not only for recording or reproducing information on a magneto-optical disk, a phase change type disk, or the like, but also for various information recording such as a magnetic recording device for recording or reproducing information by a heat assist method. It is preferably used for equipment.
- FIG. 1 is a cross-sectional view of a semiconductor laser device according to the first to sixth embodiments as viewed from a laser emitting end face direction.
- FIGS. 2A, 2B, and 2C are diagrams schematically showing a near-field image of the semiconductor laser device according to the first embodiment.
- Figure 3 shows the relationship between the spot size in the horizontal direction and the width W of the high refractive index part. is there.
- FIG. 4 is a diagram showing the relationship between the spot size in the thickness direction and the thickness D of the high refractive index portion.
- FIG. 6 is a diagram showing a relationship with W.
- 6A to 6E are diagrams showing the steps of manufacturing the semiconductor laser device according to the first embodiment.
- FIG. 7A to 7C are cross-sectional views of the semiconductor laser devices according to the ninth and tenth embodiments, as viewed from the laser emitting end face direction.
- FIG. 8 is a cross-sectional view of the semiconductor laser device according to the eleventh embodiment as viewed from a laser emitting end face direction.
- FIG. 9 is a cross-sectional view of the semiconductor laser device according to the 12th embodiment as viewed from a laser emission end face direction.
- FIG. 10 is a cross-sectional view of the semiconductor laser device according to the thirteenth embodiment as viewed from a laser emission end face direction.
- FIG. 11 is a cross-sectional view of the semiconductor laser device according to the fourteenth embodiment as viewed from a laser emission end face direction.
- FIG. 6 is a diagram showing a relationship between D and width W.
- FIG. 6 is a diagram showing a relationship between D and width W.
- FIG. 14 is a diagram showing a range of structural parameters in which the spot size is smaller than 0.28 ⁇ m in the first to fifth embodiments.
- FIG. 15 is a diagram showing a range of structural parameters in which the spot size becomes smaller than 0.28 ⁇ in the sixth embodiment.
- FIG. 16 shows that the spot size is smaller than 0.28 / zm in the seventh embodiment. It is a figure which shows the range of the structural parameter which becomes.
- FIG. 17 is a diagram showing a semiconductor laser element mounting portion in an optical head of a magneto-optical disk recording / reproducing apparatus.
- Fig. 18 is a cross-sectional view of a conventional semiconductor laser device viewed from the direction of a laser emitting end face.
- FIG. 1 shows a cross section of the semiconductor laser device of the first embodiment of the present invention (entirely denoted by the reference numeral 100), which is perpendicular to the direction of the cavity length, that is, a cross section viewed from the laser emitting end face direction.
- the semiconductor laser device 100 includes an n-type substrate 101, a flat surface 101a, an 11-type cladding layer 102, a current blocking layer 103 as an insulator layer, an active layer 104 as a high refractive index portion, and a p-type A cladding layer 105, a contact layer 106 and a p-type electrode 107 are provided, and an n-type electrode 108 is provided on the back surface 101 b of the substrate 101.
- the active layer 104 has a rectangular cross section in this example, and extends in a stripe shape in one direction perpendicular to the paper surface.
- the n-type cladding layer 102 and the p-type cladding layer 105 surround the active layer 104 as a low refractive index portion.
- the crystal growth of each layer is performed in a direction away from the substrate surface 501a from “below” to “above” in FIG.
- the conductivity type, material, and thickness of each part of the semiconductor laser device 100 are shown in Table 1 below.
- Substrate 101 n-type GaAs, thickness 100 ⁇
- ⁇ -type cladding layer 102 ⁇ -type Al. 8 Ga. . 2 As,
- Thickness (thickest part) 0.8 / zm
- the current confinement layer 103 A1 2 0 3, 20 nm thick
- Electrode for n-type 108 AuG e
- the width W of the active layer 104 was 0.25 ⁇ m.
- the region from the substrate 101 to the n-type cladding layer 102 corresponds to the n-type region
- the region from the p-type cladding layer 105 to the contact layer 106 corresponds to the p-type region.
- FIG. 2A schematically shows a near-field image 190 of a laser beam emitted from the end face of the semiconductor laser element 100
- FIGS. 2B and 2C show the thickness direction (perpendicular to the substrate surface) and the horizontal direction, respectively.
- the light intensity distribution of the near-field image 190 in the direction (parallel to the substrate surface) is shown.
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image 190 in both the thickness direction and the lateral direction was 0.23 / m. In this way, a light distribution of a perfect circle with a very small spot size 1 was obtained.
- the A1 mixed crystal ratio of the n-type cladding layer 102, the thickness of the active layer 104, and the A1 mixed crystal ratio of the p-type cladding layer 105 was configured by changing the width of the active layer 104 as follows (these changed items are the same from the third embodiment to the fifth embodiment described later).
- the crystal ratio X was 1.0, and the width W of the active layer 104 was 0.2 m.
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction was 0.2.
- spot size spot size
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction was 0.28 im.
- spot size spot size
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction was 0.28 / im.
- spot size spot size
- the A1 mixed crystal ratio x of the n-type cladding layer 102 0.5
- the thickness of the active layer 104 0 0.28 m
- the A1 mixed crystal ratio x of the p-type cladding layer 105 0.5
- the width W of the active layer 104 was set to 0.28 ⁇ m.
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction is 0.
- spot size spot size
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in the thickness direction and the lateral direction is 0.78, respectively. / m, 0.25 / m.
- the near-field image has such an elliptical shape and a large spot area, it cannot be used as a light source mounted on an optical system of the proximity recording system, which is the object of the present application.
- the conventional semiconductor laser device has no intention to obtain a minute spot which is the object of the present invention, and does not devise a configuration and a device therefor.
- the semiconductor laser device of the present invention is obtained as a result of reviewing the configuration of the semiconductor laser device from a new viewpoint of obtaining a minute spot, and the width W and thickness D of the active layer are usually By setting it to be much smaller and optimally than the semiconductor laser device of the above (manufacturing process is strictly controlled in accordance with it), a minute spot is realized. Therefore, it can be suitably used as a light source for an optical system using a minute spot. This will be described more specifically with reference to FIGS.
- the graph also shows the dependence of the spot size in the lateral direction on the width W of the active layer 104 in a semiconductor laser device in which the active layer 104 is GaAs. It was found that the spot size in the horizontal direction became extremely small near the width W of the active layer of about 0.2 m.
- FIG. 4 shows the dependence of the spot size in the thickness direction on the thickness D of the active layer 104. It was found that the spot size in the thickness direction became extremely small when the thickness D of the active layer was about 0.2 m. From these results, it is suggested that the semiconductor laser device is configured using W and D that give the minimum spot size in both the thickness direction and the lateral direction.
- Fig. 5 shows the spot size in the thickness and lateral directions (full width at half maximum of the light intensity distribution of the near-field image) when the width W and the thickness D of the active layer 104 are simultaneously changed with the same value. Is shown.
- the range in which the width W is varied is characterized in that the value is significantly smaller than the width (about 1 ⁇ m) of the conventional semiconductor laser device.
- the n-type A 1 x G ai x As clad layer 102 and the p-type Al x G a to X As clad layer 10 as low refractive index portions are used.
- the A1 mixed crystal ratio X of 5 was set to 0.8, 1.0, and 0.5, in FIG.
- this X was changed as a parameter in the range of 0.3 to 1.0 in steps of 0.1. ing.
- Arrow A in FIG. 5 is drawn on a line connecting the points where the spot size becomes minimum for each value of X. From FIG. 5, it can be seen that as the A 1 mixed crystal ratio X in the low refractive index portion increases (this corresponds to increasing the refractive index difference ⁇ n between the low refractive index portion and the high refractive index portion). It is found that the minimum spot size ⁇ S becomes significantly smaller.
- the present invention It is created from the results, and assuming that there is a refractive index difference ⁇ n between the high refractive index part and the low refractive index part forming the waveguide of the resonator, W and D are used as conventional semiconductor lasers.
- W and D are used as conventional semiconductor lasers.
- the difference in the refractive index between the active layer 104 as the high refractive index portion and the cladding layers 102 and 105 as the low refractive index portions is sufficiently large, and The width W and thickness D of the high refractive index portion are both narrow and optimally set to 0.25 im.
- a small-spot semiconductor laser device that oscillates with a very small spot size of 0.23 zm in both the thickness direction and the lateral direction was obtained.
- the obtained light spot is half the light intensity distribution.
- the total width is 0.28 ⁇ m and the l / e 2 diameter is 0.48 im.
- the semiconductor laser device of the present invention emits light with a smaller spot size while using a material having a long wavelength of 900 nm and a material whose mass production technology has been established. Therefore, by performing proximity recording using the semiconductor laser device of the present invention as a light source, it is possible to obtain an optical memory having a higher density than that of the B1 u-ray Disccj standard. Then, a well-known document (Fumio Koyama et al., "Near-field light generation by surface emitting laser", Applied Physics, Japan Society of Applied Physics, Vol. 68, No. 12, 1999, pp. 1380-1383) Since the kind of metal varnish as shown is not required, high output of several mW class is possible.
- This A 1 mixed crystal ratio X 0.5 means that the refractive index of the active layer 104 which is a high refractive index portion is n a , and the refractive index of the cladding layers 102 and 105 which are low refractive index portions is n c ,
- the thickness D and the width W of the high refractive index portion have the same value
- D and W need not necessarily be the same value. If W satisfies the conditions described above, the spot size in the horizontal direction will be sufficiently small, and if D satisfies the conditions described so far, the spot size in the thickness direction will be sufficiently small. However, it is more desirable that D and W have the same value or a value close to the value, since a spot shape that is a perfect circle or a shape close thereto can be obtained.
- FIG. 6A to 6E show a process of manufacturing the semiconductor laser device 100 according to the first embodiment.
- an n-type cladding layer 102a made of n-type A 1 GaAs and a current confinement layer made of A 1 As are first formed on a surface 101a of an n-type GaAs substrate 101 by a reduced pressure MO-CVD method.
- a p-type cladding layer 105a made of p-type A1GaAs is crystal-grown in this order.
- a mask 109 made of SiO 2 is vapor-deposited thereon, and electron beam exposure and jet etching are performed thereon.
- a stripe-shaped groove 110 having a width of 0.25 m is formed.
- an n-type cladding layer 102 b of n-type A 1 GaAs, an active layer 104 of non-doped GaAs, a p-type A p-type cladding layer 105 b of 1 GaAs is selectively grown in the trench 110.
- the shape of the laminated structure including the selectively grown layers 102b, 104, and 105b is drawn in a rectangular shape for simplicity, but is not necessarily required to be rectangular. Inclined facets may appear on the sides of the selectively grown layer.
- the mask 109 is removed and is made of p-type AlGaAs! )
- a crystal cladding layer 105c and a contact layer 106 made of p-type GaAs are crystal-grown on the entire surface.
- a 1 As which is the current confinement layer 103 is oxidized by thermal oxidation to be transformed into high-resistance A 1 O x .
- electrode 107 on contact layer 106 and electrode on back surface 101b of substrate 101 108 were each deposited to complete the device.
- the width of the active layer 104 is very narrow, but along the boundary between the p-type cladding layer 105 and the n-type cladding layer 102 around the active layer 104, the high-resistance A 1 O x (since a 1 O x is a generic term including a 1 2 0 3. consists of) current confinement layer 103 is Kai ⁇ , energizing current is interrupted by the current confinement layer 103. Therefore, current injection into the active layer 104 can be performed very efficiently.
- the active layer 104 having a narrow lateral width be p-type as shown with reference to FIGS. 6A to 6E.
- the insulating layer Sandwiched between the p-type cladding layer 105 and the n-type cladding layer 102, and along the interface between the p-type cladding layer 105 and the n-type cladding layer 102 corresponding to both sides of the active layer 104, the insulating layer (current constriction) It has been found that a configuration in which the layer 103) is interposed is desirable. Also, examples of the insulating layer, a high-resistance aluminum oxide (A10J is desirable. Part A 1 O x is your previously placed in the boundary portion minutes between the p-type cladding layer 105 and the n-type cladding layer 102 By thermally oxidizing the A 1 As layer that has been used, it can be easily manufactured.
- a semiconductor that emits light at a wavelength of 900 nm, using GaAs as the active layer (high-refractive-index portion) and using A 1 GaAs as the cladding layer (low-refractive-index portion) The case where the present invention was implemented with a laser is shown.
- the sixth embodiment a case will be described in which the present invention is implemented in a material system that emits light at a shorter wavelength of 650 nm.
- the conductivity type, material, and thickness of each part were set as shown in Table 2 below (for simplicity, FIG. The same reference numerals are used for the components corresponding to the components.)
- Substrate 101 n-type G a As, thickness 100 / im
- n-type cladding layer 102 (A 1 x Ga 5 I n 0 5 P,
- Thickness (thickest part) 0.
- the current confinement layer 103 A1 2 0 3, the thickness of 20nm Active layer 104: a non-doped G a 0. 5 I n 0. 5 P p -type cladding layer 105:.. P-type (A 1 x G ai _ x ) 0 5 I n 0 5 P,
- Contact layer 106 ⁇ -type GaAs, thickness 0.5 ⁇ m
- Electrode for p-type 107 Au Zn
- Electrode for n-type 108 AuG e
- the thickness of the active layer 104 is D, and the width is W.
- FIG. 12 shows a spot size in the thickness direction and the lateral direction when the lateral width W and the thickness D of the active layer 104 are simultaneously changed with the same value for this semiconductor laser device.
- 0.3, 0.6, and 1.0 are selected as the A1 mixed crystal ratio x of the cladding layers 102 and 105.
- the arrow A in FIG. 12 is drawn on a line connecting the points where the spot size becomes minimum for each value of X.
- the spot size is minimized by setting W and D significantly smaller and optimally than the conventional semiconductor laser device. I have. With such a configuration, the area of the near-field image can actually be minimized, and a semiconductor laser device suitable for use in an optical recording system of the proximity recording system was obtained.
- the present invention is implemented using a material system that emits light in the 405 nm band having a shorter wavelength.
- the conductivity type, material, and thickness of each part were set as summarized in Table 3 below (for simplicity, FIG. The same reference numerals are used for components corresponding to the components in the figure.)
- Substrate 101 n-type G a N, thickness 100 / im
- n-type cladding layer 102 A 1 X G X N , the thickness (thickest portion) 0. 8 ⁇ m current constricting layer 103: A 1 2 0 3, 20 nm thick
- Active layer 104 non-doped G a N
- ⁇ -type cladding layer 105 p-type A 1 X G a ⁇ N, thickness 0.8 ⁇ m
- Contact layer 106 p-type GaN, thickness 0.5 m
- the thickness of the active layer 104 is D, and the width is W.
- emission in the 405 nm wavelength band is obtained by using GaN as the material of the active layer (high refractive index portion) 104. Also, by using the A 1 X G a as the material of the cladding layer (low refractive Oriritsu unit) 102, 105. Thus, a semiconductor laser device is configured.
- FIG. 13 shows the spot size in the thickness direction and the lateral direction (near field) when the width W and the thickness D of the active layer 104 are simultaneously changed with the same value for this semiconductor laser device, as in FIG. (Full width at half maximum of the light intensity distribution of the image).
- 0.3, 0.6, and 1.0 are selected as the A1 mixed crystal ratio x of the cladding layers 102 and 105.
- the arrow A in FIG. 12 is drawn on a line connecting the points where the spot size becomes minimum for each value of X.
- the spot size is minimized by setting W and D significantly smaller and optimally than the conventional semiconductor laser device. I have. With such a configuration, the area of the near-field image can actually be minimized, and a semiconductor laser device suitable for use in an optical recording system of the proximity recording system was obtained.
- FIG. 14 shows the 900 nm band semiconductor laser device shown in the first to fifth embodiments
- FIG. 15 shows the 650 nm band semiconductor laser device shown in the sixth embodiment
- FIG. For the 405 nm wavelength band shown in the seventh embodiment, the ranges of the structural parameters ( ⁇ , D, W) where the spot size is smaller than 0.28 xm are shown.
- the range of such structural parameters ( ⁇ , D, W) is hatched with a broken line, and the boundaries of each range are denoted by LA, LB, and LC. .
- D W.
- ⁇ n (n a -n c ) (where n a is the refractive index of the active layer (high refractive index portion) 104 and nc is the refractive index of the cladding layers (low refractive index portions) 102 and 105). From FIGS. 14, 15 and 16, it can be seen that the larger the ⁇ n, the greater the structural tolerance for D and W. It can also be seen that the longer the wavelength, the greater the ⁇ is required. That is, to implement the present invention, a combination of materials having a short wavelength and a large ⁇ is desirable.
- ⁇ is the oscillation wavelength of this semiconductor laser device.
- the unit of D and W is ⁇ m, and the unit of ⁇ is nm. ).
- the thickness D and the width W of the cross-section of the active layer (high refractive index portions) 104 are each C - ⁇ (An r -A) / B ⁇ 1/2 ⁇ D ⁇ 0 + ⁇ ( ⁇ 1- ⁇ . ) / ⁇ 1 ' 2 C- ⁇ (An r -A) / B ⁇ 1/2 ⁇ W ⁇ C + ⁇ (An r -A) / B ⁇ 1/2
- the material of the active layer 104 is G a 0.93 In. .. 7 N. .. 25 As. , 975 to form a semiconductor laser device.
- the full width at half maximum of the light intensity distribution of the near-field image in the thickness direction and the lateral direction is G a 0.93 In. .. 7 N. .. 25 As. , 975 to form a semiconductor laser device.
- spot size was 0.27 / im. In this way, a perfect circle light distribution with a very small spot size was obtained. Optical output of 10mW or more could be obtained.
- a 1 Ga As is selected as the material system, and the refractive index is controlled by changing the A 1 mixture ratio to set the high refractive index portion and the low refractive index portion.
- All the layers are A
- the refractive index difference between the high refractive index part and the low refractive index part there is a limit to increasing the refractive index difference between the high refractive index part and the low refractive index part.
- the larger the difference in refractive index between the high refractive index portion and the low refractive index portion is, the more advantageous it is. Therefore, it is preferable to use a material that can further expect a difference in refractive index.
- the present invention especially when the refractive index of nitrogen (N) is mixed with GaAs or GaInAs. Since the rate of increase is significantly higher than that of other material systems, it is particularly advantageous for the present invention to use a material in which N 2 is mixed and crystallized in the high refractive index portion of the present invention.
- the material of the active layer 104 is GaInNAs, but the same effect can be obtained by using GaSbNAs or GaInNAsSb.
- FIG. 7A shows a cross section of the semiconductor laser device 200 according to the ninth and tenth embodiments.
- the components 201-203 and 205-208 of the semiconductor laser device 200 except for the refractive index portion 204 are the same as the semiconductor laser device 100 of the first embodiment (FIG.
- the respective parts 101-: L03, 105-; correspond to L08, respectively, and have the same material and thickness. Only the high refractive index portion 204 is different from that of the first embodiment.
- Quantum well layers 204 a and barrier layers 204 b are alternately stacked, and optical guide layers 204 c and 204 c are provided above and below the stack. Layer structure).
- the quantum well 204 a is In with a thickness of 7 OA. 2 G a. 8
- the barrier layer 204b is made of GaAs with a thickness of 20 OA
- the light guide layer is made of GaAs.
- the total thickness D of the high refractive index portion 204 was 0.25 ⁇ m.
- the high-refractive-index portion 204 is formed by arranging quantum dots 204 d in a discrete layer shape in a barrier layer 204 e.
- the quantum dot 204 d is composed of self-aligned InAs dots having a diameter of about 10 nm
- the barrier layer 204 e is composed of GaAs.
- the total layer thickness D of the high refractive index portion 204 was 0.25 ⁇ m.
- the semiconductor laser device of the ninth embodiment emitted laser light at a wavelength of 1 ⁇ m
- the semiconductor laser device of the tenth embodiment emitted laser light at a wavelength of 1-3 ⁇ m.
- the spot sizes in the horizontal direction and the thickness direction are 0.26 ⁇ and 0.26 / 1 m, respectively.
- the spot size in the horizontal and thickness directions was 0.28 ⁇ and 0.28 ⁇ m, respectively.
- an optical output of 1 O mW or more could be obtained.
- the entire high refractive index portion emits light as the active layer.
- the entire high refractive index portion 204 is formed. May not necessarily emit light, and may have a configuration in which a light emitting region (here, quantum well 204 a or quantum dot 204 d) is included in the high refractive index portion.
- the structure of the light emitting region is not limited to a quantum well or a quantum dot, but may be a quantum wire or GRIN-SH (Graded Index-Separate).
- the high refractive index portion is made of a single material, whereas in the ninth and tenth embodiments, a plurality of quantum wells or quantum dots including a quantum dot are used. It consists of a stack or combination of materials.
- the value of ⁇ n defined as the refractive index difference between the low refractive index portion and the high refractive index portion is calculated as follows.
- the thickness D and the width W of the cross section of the entire high-refractive-index portion 204 are smaller than the spot size in the horizontal direction and the thickness direction (full width at half maximum of the light intensity distribution of the near-field image). If the value is set to be substantially a minimum value, it can be considered that the value is included in the present invention. If the volume of the quantum well or quantum dot inside the high-refractive-index portion 204 is smaller than the entire high-refractive-index portion 204, the refractive index of the high-refractive-index portion 204 becomes almost equal to the optical guide layer 204c or It is determined by the refractive index of the barrier layers 204b and 204e.
- the difference between the refractive index of the light guide layer or the barrier layer and the refractive index of the cladding layer may be treated as ⁇ n.
- the difference between the effective refractive index of the high refractive index portion 204 (average refractive index taking into account the structure of the quantum wells and quantum dots contained therein) and the refractive index of the cladding layer is treated as ⁇ n. May be.
- FIG. 8 shows a cross section of the semiconductor laser device of the eleventh embodiment of the present invention (entirely denoted by reference numeral 300), which is a cross section perpendicular to the direction of the cavity length, that is, a cross section viewed from the laser emitting end face direction.
- the semiconductor laser device 300 includes an n-type substrate 301, a flat surface 301a, n-type cladding layers 302a and 302b, a current confinement layer 303 as an insulator layer, and an active layer 304 as a high refractive index portion.
- the active layer 304 has a rectangular cross section in this example, and extends in a stripe shape in one direction perpendicular to the paper surface.
- the n-type cladding layers 302a and 302b and the p-type cladding layers 305b and 305a surround the active layer 304 as a low refractive index portion.
- Table 4 summarizes the conductivity type, material, and thickness of each part of the semiconductor laser device 300.
- Substrate 301 n-type GaAs, thickness 10 O / zm
- n-type cladding layer 302 a 0 51 I n. , 49 P,
- n-type cladding layer 302b n-type Ga. . 51 I n. . 49 P,
- Thickness (thickest part) 0.3 / m
- the current confinement layer 303 A 1 2 0 3, the thickness of 20nm Active layer 3 04:.. Non-doped I n 0 02 G a 0 98 A s,
- Thickness D 0.25 ⁇ ⁇
- ⁇ -type cladding layer 30 5 b p-type Ga. , 51 I n 0. 49 P ,
- p-type cladding layer 30 5 a ::.. p-type (.. A l 0 8 G a 0 2) 0 51 I n 0 49 P,
- Contact layer 306 ; type G aA s, thickness 0.5 ⁇
- ⁇ -type electrode 30 7 A u ⁇ ⁇
- Electrode for n-type 308 AuG e
- the semiconductor laser device of the eleventh embodiment oscillated at a wavelength of 920 nm .
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image was 0.28 Aim in both the thickness direction and the lateral direction.
- spot size 0.28 Aim in both the thickness direction and the lateral direction.
- an optical output of 2 OmW or more was obtained.
- the active layer 304 is InGaAs
- the cladding layers 302b and 305b directly surrounding it are GaInP
- the cladding layer 30 surrounding the outside is GaInP. 2a and 305a were defined as A1GaInP.
- the material of the active layer 304 and the cladding layers 302 and 305b directly surrounding the layer 304 is made of aluminum.
- the feature is that (A 1) is not included. That is, when the spot size of the near-field image is reduced as in the semiconductor laser device of the present invention, the light density in the active layer is significantly increased, and the high light density causes the laser emission end face or the inside of the laser resonator to be invisible. Damage is more likely to occur. In particular, when A1 is contained in the crystal, oxidation of A1 at the end face of the cavity and induction of defects involving A1 inside the cavity are liable to occur, thereby causing deterioration of the semiconductor laser device. .
- the active layer (high-refractive-index portion) 304 having the highest light density and directly surrounding the active layer 304 It is assumed that the material of the cladding layers 302b and 305b does not contain aluminum (A1). As a result, such deterioration can be prevented, and stable operation up to high output can be performed.
- this embodiment shows an example using the I n G a A s and G a I n P as mixed crystals crystals does not include A 1, G a x I n It can be composed of any mixed crystal system described by y (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1).
- the active layer (high-refractive-index portion) 304 and the cladding layer (part of the low-refractive-index portion) directly surrounding the active layer (a portion of the low-refractive-index portion) 302 b and 300 b are made of aluminum.
- a GaInAsP-based material InGaAs and GaInP
- the refractive index difference between the two may be large in this material system. Can not. Therefore, in the present embodiment, outside the cladding layers 302 b and 305 b (regions where the optical density is low), the cladding layers 302 a and 252 a made of A 1 G a In P having a lower refractive index are further provided.
- the low-refractive-index portion is made of one type of material, whereas in the present embodiment, the low-refractive-index portion is made of two types of materials having different refractive indexes. It has a configuration. In the case where the structure of the low refractive index portion is not a single structure but is made of a plurality of materials, it is possible to specify the value of the refractive index difference ⁇ n between the high refractive index portion and the low refractive index portion.
- the thickness D and the width W of the cross section of the high refractive index portion are at or near the value at which the spot size of the near-field image in the thickness direction and the horizontal direction is minimized, respectively. If set to, it is included in the present invention.
- FIG. 9 is a cross-sectional view of the semiconductor laser device according to the 12th embodiment of the present invention (entirely denoted by reference numeral 400), which is a cross-section perpendicular to the cavity length direction, that is, a cross-section viewed from the laser emission end face direction. Is shown.
- This semiconductor laser device 400 has an n-type cladding layer 402, a current confinement layer 4003a, 4003b, and 4003c on a flat surface 401a of a substrate 401.
- An active layer 404 as a high-refractive-index portion, a p-type cladding layer 405, a contact layer 406a, 406b, and a p-type electrode 407, and the back of the substrate 401.
- the surface 410b is provided with an n-type electrode 408.
- Active layer 104, p-type cladding layer 4 05 and the contact layer 406a have a rectangular cross section of the same width in this example, and extend in a stripe shape in one direction perpendicular to the paper surface.
- Portions of the n-type cladding layer 402 corresponding to both sides of the active layer 404 are processed so as to form a curved slope (convex downward).
- the flow constriction layers 403a, 403b, 403c are provided so as to fill both sides of the n-type cladding layer 402, the active layer 404, and the type cladding layer 405 and the contact layer 406a.
- the n-type cladding layer 402, the p-type cladding layer 405, and the current confinement layers 403a, 403b, 403c surround the active layer 404 as low refractive index portions.
- the conductivity type, material, and thickness of each part of the semiconductor laser device 400 are summarized in Table 5 below.
- Substrate 40 1 n-type G a As, thickness 10 1 ⁇
- n-type cladding layer 40 2 .. n-type A 1 0 6 G a 0 4 A s,
- Thickness (thickest part) 0.8 / im
- the current confinement layer 40 3 a :.. N-type A 1 0 8 G a 0 2 A s
- the current confinement layer 40 3 b ::.. Type A 1 0 8 G a 0 2 A s
- the current confinement layer 40 3 c :.. N-type A 1 0 8 G a 0 2 A s
- Type cladding layer 40 5 type A 10. 6 G a 0 .4 A s, a thickness of 0. 8 ⁇ contactor coat layer 40 6 a, 406 b: ⁇ type G a A s, a thickness of 0. 5 m
- Electrode for p-type 40 7 Au Zn
- Electrode for n-type 40 8 AuG e
- the width W of the active layer 404 was set to 0.33 m.
- the mixed crystal ratio of the low refractive index portion was uniform around the high refractive index portion.
- the active layer 4 as a high refractive index portion is used.
- the mixed crystal ratios of the AI GaAs cladding layers 402 and 405, which are vertically in contact with 04, and the A 1 GaAs current confinement layers 403a, 403b, 403c, which are right and left, are different from each other.
- the mixed crystal ratio of the low refractive index portion is different around the portion.
- the thickness D and the width W of the cross section of the high refractive index portion are in the thickness direction and the horizontal direction.
- the present invention is included in the present invention if the spot size of the near-field image is set to a value at which the spot size of the near-field image is minimized or a value close to the value.
- the width W of the active layer forming the high refractive index portion is significantly smaller than that of the conventional semiconductor laser device as in the present invention, a structure capable of efficiently injecting current into the active layer is provided. It is important to do.
- Current constriction may be performed using an insulator (A 1 OJ) as in the first embodiment, or current constriction may be performed using a pn reverse junction as in the twelfth embodiment.
- the current confinement may be performed using a high-resistance semiconductor material such as a Cr-0 doped crystal or an AND crystal.
- the semiconductor laser device of the twelfth embodiment is manufactured as follows, unlike the semiconductor laser device of the first embodiment or the like in which the active layer is crystal-grown using selective growth. That is, after the n-type cladding layer 402, the active layer 404, the p-type cladding layer 405, and the contact layer 406a are continuously crystal-grown on the surface 401a of the substrate 401 in a single step, a stripe-shaped mask is used. Mesetsuting is performed until these layers have a stripe shape and portions corresponding to both sides of the n-type cladding layer 402 have curved slopes.
- current constriction layers 403a, 403b, and 404c are selectively stacked so as to fill both sides of the layers 402, 404, 405, and 406a. Then, after a contact layer 406b is laminated on the entire surface, an electrode 407 is deposited on the contact layer 406b and an electrode 408 is deposited on the back surface 401b of the substrate 401, thereby completing the device.
- FIG. 10 shows a cross section of a semiconductor laser device (entirely denoted by reference numeral 500) of a thirteenth embodiment of the present invention, the cross section being perpendicular to the direction of the cavity length, that is, the cross section viewed from the laser emitting end face direction.
- This semiconductor laser device 500 has an n-type cladding layer 502 on a surface 501 a of a substrate 501 on which a V-shaped groove (width W1) is formed.
- An active layer 504 as a refractive index portion, a p-type cladding layer 505, a contact layer 506, a current confinement layer 503, and a p-type electrode 507 are provided, and the back surface 501b of the substrate 501 is provided.
- the n-type cladding layer 502, the p-type cladding layer 505, and the like are each formed to be approximately V-shaped in cross-section, reflecting the V-shape of the substrate surface 501a, and the cladding layers 502, 50
- An active layer 504 is provided between the bent portions 5.
- the active layer 504 has an inverted triangular cross section (consisting of three surfaces 504a, 504b, and 504c), and extends in a stripe shape in one direction perpendicular to the paper surface.
- the n-type cladding layer 502 and the p-type cladding layer 505 surround the active layer 504 as low refractive index portions. Table 6 below summarizes the conductivity type, material, and thickness of each part of the semiconductor laser device 500.
- Substrate 50 1 n-type G a A s, thickness 100 / xm
- n-type cladding layer 5 0 2 0 2:. n-type (.. A l 0 s G a 0 2) 0 5 I ⁇ . . 5 mm,
- Active layer 5 04 Undoped G a 0 5 I n 0 5 P,
- Thickness (thickest part) D 0.3 ⁇
- ⁇ -type cladding layer 5 0 5:.. (. . A l 0 8 G a 0 2) 0 5 I n 0 5 P,
- Contact layer 506 p-type G a A s, thickness 0.5 ⁇ ⁇
- ⁇ -type electrode 5 0 7 Au ⁇ ⁇
- Electrode for ⁇ type 508 AuG e
- the width W of the inverted triangular active layer 504 was 0.35 X m.
- the semiconductor laser device 500 When a current was injected into the semiconductor laser device 500 through the electrodes 507 and 508, laser oscillation was generated at a wavelength of about 600 nm.
- the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction was 0.3 ⁇ .
- spot size the full width at half maximum (spot size) of the light intensity distribution of the near-field image in both the thickness direction and the lateral direction was 0.3 ⁇ .
- spot size spot size
- an optical output of 1 OmW or more was obtained.
- the semiconductor laser device having a narrow and active layer formed by selective growth using a narrow mask or mesa etching using a narrow mask is described. The configuration and manufacturing method are shown. However, in order to manufacture them, a mask having a width as small as submicron is required.
- a V-groove having a relatively wide width W1 is formed on the substrate surface 5Ola, and each layer is formed by crystal growth on the V-groove.
- An active layer 504 having an extremely narrow width W can be easily obtained without using it.
- a V groove having a relatively wide width W1 is formed on the surface 501 of the GaAs substrate 501, and the MOC VD is formed on the substrate surface 501a having the V groove.
- an A1GaAs cladding layer 502 is formed by a method (organic metal vapor phase epitaxy).
- the GaAs active layer 504 is crystal-grown. By remarkably reducing the growth rate during this crystal growth, it is possible to grow the crystal thicker at the portion (bent portion) corresponding to the bottom of the V-groove and thinner at the portion (slope) corresponding to the side surface of the V-groove.
- an active layer 504 having an inverted triangular cross section can be manufactured.
- a small-volume active layer 504 having a desired narrow width W and thickness D can be manufactured with good controllability without using a narrow mask.
- the same material as the active layer, G a As, which is thinner at the portion (slope) corresponding to the side surface of the V-groove, has a small volume, so the effect on the formed waveguide structure is small. V, very small.
- the shape of the active layer 504 is an inverted triangle, but by setting W and D optimally, it is possible to set the spot size of the near-field image in the thickness direction and the lateral direction to be extremely small. Was.
- the configuration example of the semiconductor laser device that emits infrared light has been described.
- the semiconductor laser device that emits visible light can be configured as in the present embodiment. It is also possible to configure a semiconductor laser device using a nitride-based semiconductor material using a sapphire substrate or the like, and to configure a semiconductor laser device that oscillates in green, blue, and ultraviolet.
- FIG. 11 shows a cross section perpendicular to the cavity length direction, that is, a cross section viewed from the laser emission end face direction, of a semiconductor laser device (entirely denoted by reference numeral 600) of the fourteenth embodiment of the present invention.
- This semiconductor laser device 600 has an n-type cladding layer 602, an active layer 604 as a high-refractive-index portion, and a p-type cladding on a surface 601a of a substrate 601, on which a trapezoidal mesa (width W2) is formed.
- the substrate 601 includes a layer 605, a contact layer 606, a current confinement layer 603, and a p-type electrode 607, and an n-type electrode 608 on the back surface 601b of the substrate 601.
- the n-type cladding layer 602, the p-type cladding layer 605, and the like are each formed to have a substantially inverted V-shaped cross section, reflecting the trapezoidal shape of the substrate surface 6 O la, between the bent portions of the cladding layers 602, 605.
- the active layer is provided with 604 force S.
- the active layer 604 has a trapezoidal shape (consisting of a lower surface 604a, a slope 604b, 604c, and an upper surface 604d), and extends in a stripe shape in one direction perpendicular to the paper surface. I have.
- the n-type cladding layer 602 and the p-type cladding layer 605 surround the active layer 604 as low refractive index portions.
- the conductivity type, material, and thickness of each part of the semiconductor laser device 600 are summarized in Table 7 below.
- Substrate 601 n-type G a A s, thickness 100 / xm
- n-type cladding layer 602 .. n-type A 1 0 9 G a 0 x A s, a thickness of 0. 8 mu m
- Active layer 604 Non-doped G a As,
- Thickness (thickest part) D 0.15 ⁇
- Type cladding layer 605 Type A 10. 8 G a 0 2 A s, a thickness of 0. 8 ⁇
- Contact layer 606 ⁇ -type G a As, thickness (thinest part) 0.5
- P-type electrode 607 AZn
- Electrode for n-type 608 AuGe
- width W (width of the widest surface 504a) of the trapezoidal active layer 604 was set to 0.25 ⁇ m.
- the thickness direction In the horizontal direction, the full width at half maximum (spot size) of the light intensity distribution of the near-field image was 0.25 ⁇ .
- spot size In the horizontal direction, the full width at half maximum (spot size) of the light intensity distribution of the near-field image was 0.25 ⁇ .
- a V-groove having a relatively wide width W2 is formed on the substrate surface 61a, and each layer is formed by crystal growth on the V-groove.
- An active layer 604 having an extremely narrow width W can be easily obtained without using a narrow mask.
- a trapezoidal mesa having a relatively wide width W2 is formed on the surface 601a of the GaAs substrate 601, and the MOC is formed on the substrate surface 61a having the trapezoidal mesa.
- an A 1 GaAs cladding layer 602 is formed by (metal organic chemical vapor deposition).
- the GaAs active layer 604 is crystal-grown. By significantly lowering the growth rate during this crystal growth, it is possible to grow the crystal thicker at the portion (bent portion) corresponding to the top of the trapezoid and thinner at the portion (slope) corresponding to the side surface of the trapezoid. Active layer 604 can be produced. Subsequently, the remaining layers 605, 606, ... are crystal-grown thereon. By manufacturing in this manner, a small-volume active layer 604 having a desired narrow width W and thickness D can be manufactured with good controllability without using a narrow mask.
- the shape of the active layer 604 is trapezoidal, by setting W and D optimally, it was possible to set the spot size of the near-field image in the thickness direction and the lateral direction to be minimized.
- the semiconductor laser device of each of the embodiments described above has characteristics that can be preferably applied to an optical head for performing recording and reproduction on an optical disk or a magneto-optical disk by the proximity recording method.
- a sufficiently large light output can be obtained even with a small spot, so that it has sufficient characteristics to perform high-speed writing on a magneto-optical disk, etc.
- the cross-sectional shape of the active layer is not limited to those described in the above embodiments. If the cross-sectional shape of the active layer is circular, a circular spot with the smallest spot size This is more preferable.
- the shape may not be a perfect circle but may be a polygonal cross section such as a hexagon.
- the method of manufacturing the semiconductor laser device, the configuration, the material, the composition of the mixed crystal, and the like are not limited to the methods illustrated in the above embodiments.
- the present invention requires an active layer having a small width, and various means can be applied to a method for obtaining an active layer having a small width.
- “in situ” selective growth in which selective growth is performed while performing focused ion beam electron beam lithography in a crystal growth chamber, is an effective means for obtaining a narrow active layer.
- known means such as near-field lithography X-ray lithography, electron beam lithography, and exposure using a phase shift mask can be applied.
- the crystal growth method, the growth conditions, and the raw materials of the respective constituent elements are not limited to the specific methods, conditions, raw materials, or the specific combinations described in the embodiments.
- a mixed crystal system described by A 1 Ga As, Ga in NA s S b and the like is taken as an example of the III-V compound semiconductor, but a group III element other than that described in the embodiment ( B, T1, etc.) and Group V elements (P, Bi) may be appropriately mixed and crystallized, or impurity elements (Zn, Be, Mg, Te'S, Se, Si, etc.) ) May be included as appropriate.
- the substrate is not limited to those described in the embodiment, and similar effects can be obtained by using another substrate.
- III-V compound semiconductor substrates such as InP, InGaAs, GaSb, and GaN substrates
- 11-VI compound semiconductor substrates such as ZnSe and ZnS substrates
- Ge Group IV semiconductor substrates
- Si and SiC substrates glass, plastic, ceramics, sapphire spinel, etc.
- the oscillation wavelength of the laser is not limited to infrared, and any wavelength such as red, blue, violet, or ultraviolet can be selected.
- FIG. 17 shows an optical head of a magneto-optical disk recording / reproducing apparatus equipped with the same semiconductor laser device 2501 as that of the first embodiment as viewed obliquely.
- the optical head has a suspension 250 attached to the actuator 250, a slider 250 attached to the suspension 250, and an end face of the slider 250, A semiconductor laser element 2501 mounted so that the laser light emitting end face faces the disk-shaped recording medium 2502. The distance from the laser light emitting end face of the semiconductor laser 2501 to the recording medium 2502 is
- the slider 2503 is supported by a suspension 2504, and follows or accesses a desired recording track on the recording medium 2502 by the actuator 2505.
- the laser beam emitting end face of the semiconductor laser 2501 is close to the recording medium 2502, and the near-field image (the near-field pattern) of the semiconductor laser element 2501 is transferred to the recording medium 2502. Is done.
- the actuator 250 and the suspension 250 are arranged such that the distance between the light emitting end face of the semiconductor laser element 2501 and the recording medium 2502 is less than 1 / m. It acts as a control mechanism for controlling the interval.
- a minute spot could actually be formed on the recording medium 2502. Further, as compared with the conventional case where near-field light is used as a light source, the output of the semiconductor laser of the present invention can be remarkably increased, so that the time required for recording can be greatly reduced.
- the recording medium a magneto-optical disk, a phase change disk, or the like can be used.
- a magneto-optical disk recording / reproducing device is illustrated as an example of an information recording device equipped with the semiconductor laser device of the present invention.
- the semiconductor laser device of the present invention may be mounted on various other information recording devices. Needless to say, this is possible.
- the semiconductor laser device of the present invention can be mounted on a magnetic recording device or the like that records or reproduces information by a heat assist method.
- the semiconductor laser device of the present invention can obtain a light spot smaller than that of a blue semiconductor laser device using an existing compound semiconductor material, and has a metal aperture used for a proximity recording method.
- the optical head of the present invention includes such a semiconductor laser element, that is, a semiconductor laser element capable of obtaining a sufficiently large optical output despite being a small spot, thereby providing an optical disk or a magneto-optical disk with a proximity recording method. Can be used for recording playback.
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JP2002076515A (ja) * | 2000-09-04 | 2002-03-15 | Nec Corp | 半導体レーザ装置及びその製造方法 |
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JPS50119584A (ja) * | 1974-03-04 | 1975-09-19 | ||
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ITO YOSHIKAZU ET AL.: "Handotai laser kiso to oyo - shohan", BAIFUKAN CO., LTD., 25 April 1989 (1989-04-25), pages 13 - 15,30-36,44-65,103-108, XP002904497 * |
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