JP4029538B2 - Semiconductor laser, optical head, optical disk apparatus, and method of manufacturing semiconductor laser - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser that emits laser light using a self-coupling effect, an optical head, an optical disk device, and a method for manufacturing a semiconductor laser, and in particular, by increasing the intensity of laser light emitted from a minute aperture. The present invention relates to a semiconductor laser, an optical head, an optical disc apparatus, and a method for manufacturing a semiconductor laser, which can increase the recording density of a recording medium, and are reduced in size and improved in data transfer rate.
[0002]
[Prior art]
In optical disc devices, optical discs are being increased in density and capacity from compact discs (CDs) to digital video discs (DVDs), but this is in line with higher computer performance and higher definition display devices. Larger capacity is required.
[0003]
The recording density of the optical disc is basically suppressed by the diameter of the light spot formed on the recording medium. As a means for obtaining a light spot below the diffraction limit of laser light, a method of using a near-field light that has a minute aperture at a light spot position of a transparent condensing medium and oozes from the spot is attracting attention. However, in this method, since the light utilization efficiency is low, the intensity of the near-field light that oozes out is low, and a recording mark smaller than the recording mark (about 0.1 μm) obtained by condensing with a conventional lens is still obtained. Absent.
[0004]
As means for solving this problem, a recording / reproducing method using a self-coupling effect (SCOOP effect) of a semiconductor laser has been proposed. In other words, this method is a method in which a minute aperture is formed at the spot position on the output surface of the semiconductor laser, and laser light emitted from the aperture is used for recording / reproduction. In particular, during reproduction, reflected light from the recording medium is used. The laser beam is re-entered into the laser resonator through the minute aperture, and the modulation of the oscillation state of the laser caused thereby is detected electrically and optically. According to this detection method, since the sensitivity is high, it is possible to reproduce even if the re-incident light is weak.
[0005]
As a conventional optical head using this method, for example, A.I. “Tech. Dig. ISOM / ODS '99, ThC-1 (1999) p. 352” (hereinafter referred to as “Document I”) published by Partovi, and “Jpn. J. J. published by S. Shimada”. Appl. Phys.38 (1999) Pt.2, No. 11B, p.L1327. ”(Hereinafter referred to as“ Document II ”).
[0006]
FIG. 8 shows a conventional optical head described in Document I above. In this optical head 1, an edge-emitting semiconductor laser 2 is disposed at the rear end portion 11 a of the flying slider 11. This edge-emitting semiconductor laser 2 has a high-reflection multilayer film 10a and a low-reflection multilayer film 10b constituting a resonator having an oscillation wavelength of 980 nm arranged on the rear end face and the front end face of the oscillation region 8, respectively, and the low-reflection multilayer film 10b. The metal light-shielding body 4 in which the minute opening 5 is formed by etching using a focused ion beam (FIB) of Ga ions is disposed on the surface. In such a configuration, recording / reproducing is performed by irradiating the phase-change recording medium 7a of the optical disc 7 with a laser beam 6 of a small size emitted from the minute aperture 5. At the time of reproduction, the reflected light from the recording medium 7a is re-entered into the resonator of the semiconductor laser 2 through the minute aperture 5, and the self-coupling effect, that is, the modulation of the semiconductor laser 2 by the re-incident light is detected electrically or optically. By doing so, information is reproduced. The recording density can be increased by using the laser beam 6 miniaturized by the minute aperture 5 for recording and reproduction.
[0007]
FIG. 9 shows a conventional semiconductor laser described in Document II. This semiconductor laser 2 is a surface emitting semiconductor laser 2 made of an AlGaAs-based semiconductor crystal and oscillating at a wavelength of 850 nm. A highly reflective multilayer film 10a, a P-type AlAs layer 33, and a P-type spacer layer 34 are formed on a GaAs substrate 11. Then, a highly reflective multilayer film 10c having a partial transmittance and a phase adjustment layer 35 are sequentially formed, and a minute opening 6 is formed on the output surface 3 of the semiconductor laser 2 above the oscillation region 8 by etching using a focused ion beam. The metal light-shielding body 4 is arranged. The high-reflection multilayer film 10a and the high-reflection layer film 10c constituting the resonator are configured by alternately stacking ¼ layer thickness GaAs layers and AlGaAs layers. The output-side resonator mirror is composed of the highly reflective multilayer film 10 c and the metal light-shielding body 4. In addition, since the phase of the reflection at the metal light-shielding body 4 is reversed, the phase adjustment layer 35 made of AlGaAs having a thickness that makes the optical path length ¼ wavelength is sandwiched, and the reflection is adjusted so as to strengthen the reflection of both. . The recording density can be increased by using the laser beam 6 miniaturized by the minute aperture 5 for recording and reproduction.
[0008]
On the other hand, although it is a semiconductor laser that emits laser light using the self-coupling effect, as a semiconductor laser having a configuration different from the above two conventional examples, see, for example, the 73rd Micro-Optics Society document, p. 27, (1999, September).
[0009]
FIG. 12 shows the semiconductor laser. This semiconductor laser 2 is a surface-emitting type semiconductor laser, and a pyramid-shaped condensing body 61 called a total reflection tip formed by a semiconductor material provided on the output surface of the laser 2, and a condensing light A conical central metal body 66 provided at the tip of the body 61, a micro coaxial body 65 made of carbon nanotubes formed at the tip of the central metal body 66, the light collector 61, the central metal body 66, and the micro A metal film 63 is formed around the coaxial body 65 via a dielectric layer 62. According to this configuration, as shown in FIG.
A small-sized propagating light (TEM00 mode) is to be obtained from the small coaxial body 65.
[0010]
[Problems to be solved by the invention]
However, according to the conventional semiconductor laser shown in FIGS. 8 and 9, since an air gap is formed between the recording medium and the thickness of the metal light-shielding member provided on the laser light output surface, the recording density is increased. However, there is a problem that even if the size of the minute aperture is reduced, the output power is drastically decreased more than inversely proportional to the area of the aperture, and the recording density cannot be improved.
[0011]
In other words, in the case of a simple aperture, as can be inferred from a microwave waveguide, the cutoff is cut off when the aperture is 1/2 or less of the wavelength, and the laser beam that can pass through decreases exponentially as the aperture becomes narrower. To do. In this case, the laser light is mainly present near the interface as near-field light, but its spreading length is about the size of the opening. When the aperture width is 100 nm, the depth and the aperture width are approximately the same as shown in FIG. 10A, and the near-field light is in the normal direction of the aperture as shown in FIG. The intensity decreases exponentially and hardly reaches outside the surface 4a of the metal light shield 4. For this reason, as described above, when the opening size is reduced, the power is rapidly reduced.
[0012]
FIG. 11 shows the relationship between the aperture size and the optical output power. As the recording / reproducing optical recording medium, there are a phase change recording medium mainly composed of GeSbTe or the like and a magneto-optical recording medium mainly composed of FeTbCo or the like. ⁶ W / cm ² An optical power density of about 20 mW when the light spot diameter is 1 μm is required. On the other hand, as shown in the figure, when the aperture size is 0.1 μm and 0.05 μm, the output power is 0.1 mW and 0.01 mW, respectively, and the optical power density is 1.8 × 10 respectively. ⁶ W / cm ² 0.7 × 10 ⁶ W / cm ² Suddenly decreases to a fraction of the optical power density required for recording, resulting in insufficient output.
[0013]
FIG. 13 shows a problem of the conventional surface emitting semiconductor laser 2 shown in FIG. As shown in the figure, most of the output light of the surface-emitting type semiconductor laser 2 is configured to be totally reflected twice and returned to the surface-emitting type semiconductor laser 2 on the inclined surface 61a of the pyramid-shaped condensing body 61. The slope 61a itself serves as a part of the reflecting mirror of the output-side resonator of the laser 2. Therefore, the inclination angle of the slope 61a is formed at 45 degrees. A dielectric layer 62 is provided on the outside of the dielectric layer 62. The refractive index of the dielectric layer 62 that can be formed by vapor deposition or sputtering is 2.2 at most, whereas the refractive index of the laser semiconductor is 3. Since the critical angle of incidence is about 38 degrees, the incident angle of 45 degrees certainly satisfies the condition of total reflection and is totally reflected by the inclined surface 61a of the semiconductor light collector 61. Then, the output light is emitted from a portion where the apex of the pyramidal condensing body 61 is dull and curved. However, a coaxial central metal body 66 is formed at the apex portion, and most of the output light is reflected or absorbed by the central metal body 66, so that almost the light reaches the micro coaxial body 65. It is a structure that cannot be obtained. Even if the light leaks from the inclined surface 61a of the light collector 61, it is reflected in the laser direction by the metal film 63 or absorbed as is well known in a microtapered probe, and is still almost microcoaxial body 65. The laser beam does not reach and the required light intensity is not obtained.
[0014]
Accordingly, an object of the present invention is to increase the intensity of the laser light emitted from the minute aperture, thereby enabling a high recording density of the recording medium, and reducing the size and improving the data transfer rate. An object is to provide a head, an optical disk device, and a method of manufacturing a semiconductor laser.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is positioned on the laser beam emission side. On a flat surface Configure part of the resonator Having a size of 100 nm or less A metal light-shielding body in which a minute opening is formed, and a central metal body is provided at the center of the minute opening, and in the minute opening To be almost the same surface as the surface of the metal shading body Provided is a semiconductor laser in which a laser light transmitting material is embedded.
According to the above configuration, the wavelength of the laser beam in the aperture is shortened in inverse proportion to the refractive index of the laser beam transmitting material, so that the ratio of the aperture width to the wavelength is increased in proportion thereto, and the laser beam is opened. It becomes easy to pass through. A coaxial opening is formed from the minute opening and the central metal body, and propagating light is output from the coaxial opening. Since the surface that outputs this propagating light moves from the original laser beam output surface to the surface of the material embedded in the microscopic aperture, the distance between the surface that outputs the propagating light and the recording medium can be reduced, Propagating light can be efficiently incident on the recording medium. Note that examples of the laser light transmissive material embedded in the minute openings include a material constituting a part of the semiconductor laser structure and an antireflection film. Semiconductor laser structures include reflective films, multilayer reflective films, active layers, clad layers, or window materials that have a wider band gap than the active layer and are provided on the end face of the active layer, one or more of which are minute It is configured to be embedded in the opening. In addition, as an antireflection film, SiO ₂ A dielectric material such as can be used.
[0016]
In order to achieve the above object, the present invention is positioned on the laser beam output side. On a flat surface Configure part of the resonator Having a size of 100 nm or less A metal light-shielding body in which a minute opening is formed, and a central metal body is provided at the center of the minute opening, and in the minute opening To be almost the same surface as the surface of the metal shading body There is provided an optical head comprising: a semiconductor laser in which a laser light transmitting material is embedded; and a flying slider that holds the semiconductor laser and floats on an optical disk.
[0017]
In order to achieve the above object, the present invention provides an optical disk on which a recording medium is formed and a laser beam output side. On a flat surface Configure part of the resonator Having a size of 100 nm or less A metal light-shielding body in which a minute opening is formed, and a central metal body is provided at the center of the minute opening, and in the minute opening To be almost the same surface as the surface of the metal shading body There is provided an optical disk apparatus comprising an optical head having a semiconductor laser in which a laser light transmitting material is embedded, and a flying slider that holds the semiconductor laser and floats on the optical disk.
[0018]
In order to achieve the above object, the present invention provides a semiconductor laser material having a laser beam output surface, and forms a recess by etching a portion excluding a donut-shaped region set on the laser beam output surface. A metal body is deposited on the recess by a photolithography process or a focused ion beam method. Thus, the semiconductor laser according to claim 1 is manufactured. A method for manufacturing a semiconductor laser is provided.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1A shows an optical head according to the first embodiment of the present invention, and FIG. 1B shows a main part of a semiconductor laser used therefor. In addition, the size of each part is not according to the dimension, and the smaller and thinner part is enlarged. This optical head 1 has a flying slider 11, and an edge-emitting semiconductor laser 2 oscillating at a wavelength of 650 nm made of an AlGaInP-based semiconductor crystal is arranged at the rear end portion 11 of the flying slider 11. .
[0020]
In the edge-emitting semiconductor laser 2, as shown in FIG. 1A, the high-reflection multilayer film 10 a and the low-reflection multilayer film 10 b constituting the resonator of the laser 2 are arranged on the rear end face and the front end face of the crystal part 20, respectively. The metal light-shielding body 4 having the coaxial opening 15 is disposed on the surface of the low reflection multilayer film 10b. The coaxial opening 15 includes a rectangular opening 50 and a central metal body 51 having a rectangular shape that is coaxially disposed at the center of the opening 50.
[0021]
The highly reflective multilayer film 10a has a reflectivity of about 95%. On the other hand, the low-reflection multilayer film 10b is formed on the crystal cleavage surface 26 and has a high refractive index TiO. ₂ And low refractive index SiO ₂ It has a reflectance of about 20 to 30%.
[0022]
The metal light shield 4 is made of Ag having a thickness of 60 nm, reflects a considerable portion of the laser light into the laser 2 and constitutes a composite resonator together with the low reflection multilayer film 10b. In addition, the metal light-shielding body 4 may be another metal as long as the adherence is good. When the central metal body 51 arranged at the center of the coaxial opening 15 is about 1/3 of the size of the opening 50, the attenuation of the laser beam due to the coaxial is the smallest, but if it is about 20 nm or less, the attenuation is reduced. Is negligible, so the size is 20 nm. The length of the side of the opening 50 is not particularly limited, but about 50 to 100 nm is suitable for stable production. Each side is arranged so as to be parallel or perpendicular to a recording track (not shown) of the optical disc 7.
[0023]
As shown in FIG. 2B, the crystal unit 20 sequentially stacks an n-type AlGaInP cladding layer 22, a GaInP active layer 23, a p-type AlGaInP cladding layer 24, and a GaAs cap layer 25 on a GaAs substrate crystal 21. It is what. The metal light-shielding body 4 is formed on the tip surface of the crystal part 20, and the coaxial opening 15 and the metal light-shielding body 4 are made of SiO. ₂ It is covered with an antireflection film 27 made of
[0024]
In the coaxial opening 15, as shown in FIG. 5B, the low reflection multilayer film so that the surface (output surface) 3 of the low reflection multilayer film 10 b and the surface 4 a of the metal light-shielding body 4 are substantially flush with each other. 10b is embedded, and the surface 3 side of the opening 5a embedded in the coaxial opening 15 has a high refractive index (about 2.25) TiO. ₂ The film 5b is disposed.
[0025]
An example of a method for forming the coaxial opening 15 will be described. Parts of the low reflection multilayer film 10b other than the donut-shaped opening 5a embedded in the coaxial opening 15 are removed by etching, and the metal light-shielding body 4 and the central metal body 51 are attached to the removed part. Although a photolithography process can be used for etching, the edge surface width of the edge-emitting semiconductor laser is as narrow as 0.5 mm or less, and therefore, by focused ion beam (FIB method) using Ga ions. It is preferred to do so. For the deposition of the metal shading body 4 and the central metal body 51, the FIB method may be used similarly to the etching. Since the metal light-shielding body 4 has a thickness of 60 nm, it is possible to prevent leakage of laser light from this portion.
[0026]
Next, the operation of the optical head 1 of the present embodiment will be described. Here, a description will be given of an optical disk 7 in which a phase change recording medium 7a made of GeSbTe is formed on a substrate 7b as an object to be recorded and reproduced. The present optical head 1 floats on the recording medium 7 a of the disk 7 by a flying slider 11 with a flying height of several tens of nanometers. The edge-emitting semiconductor laser 2 oscillates between the reflective multilayer films 10a and 10b constituting the resonator when a forward current is applied. When the input of the edge emitting semiconductor laser 2 is modulated based on the recording information, the laser beam 6 is radiated from the coaxial opening 15 as propagating light by the modulation. Recording is performed by irradiating the recording medium 7a with the propagating light. During reproduction, the laser 2 is not modulated, the continuous light is irradiated onto the recording medium 7 a, and the reflected light from the recording medium 7 a is incident again into the laser 2 through the coaxial opening 15. This re-incident light modulates the oscillation state of the laser 2 itself (self-coupling effect), and information is reproduced by electrically detecting it from an input terminal (not shown) of the laser 2.
[0027]
According to the first embodiment described above, the low-reflection multilayer film 10b, which is a semiconductor laser material, is embedded in the coaxial opening 15, and TiO having a high refractive index is formed on the surface (output surface) 3 side of the opening 5a. ₂ Since the film 5b is arranged, this TiO ₂ The wavelength of the laser beam in the film 5b is shortened (300 nm or less), and the laser beam is easily emitted from the coaxial opening 15. Further, by using the rectangular coaxial opening 15, the radiated light also has a rectangular shape, and even if the recording track width is narrowed, there is little crosstalk with adjacent tracks, and the recording density in the track direction can be increased.・ High-density recording is possible. Further, since the antireflection film 27 is provided on the surface 3 of the coaxial opening 15, reflection inside the laser 2 at the coaxial opening 15 can be reduced, and light utilization efficiency can be further increased. Further, since the entire metal light shielding body 4 is covered with the antireflection film 27, a photolithography process is not required when the antireflection film 27 is deposited, and the metal light shielding body 4 has an effect as a protective film.
Note that a photodetector (not shown) may be provided outside the highly reflective multilayer film 10a at the rear end of the laser 2, and the modulation state of the laser 2 may be detected by the photodetector. In this case, the SN ratio of the reproduction signal can be increased by slightly reducing the reflectance of the highly reflective multilayer film 10a and increasing the transmittance to 10% or more.
[0028]
FIG. 2 shows a main part of a semiconductor laser according to the second embodiment of the present invention. The second embodiment is an edge-emitting semiconductor laser 2 similar to the first embodiment, but the side of the short side direction of the coaxial opening 15 is 1 / of the wavelength in the resonator of the laser 2. The opening 50 of the present embodiment has a rectangular shape of, for example, 50 nm × 150 nm, which is shorter than 2 and whose longitudinal side is longer than ½ of the wavelength in the resonator of the laser 2. . Similarly, the minute metal body 51 has a rectangular shape along the opening 50. This edge-emitting semiconductor laser 2 has a refractive index guided structure in which the oscillation region 8 is limited by a ridge 28, and a quantum well having a width of about 10 nm is used for the active layer 23. The oscillation region 8 has an elliptical shape with a horizontal direction of 2 to 3 μm and a vertical direction of 1 μm with the active layer 23 as the center. The coaxial opening 15 is provided substantially at the center of the oscillation region 8 and the side in the longitudinal direction is parallel to the active layer 23 as shown in FIG. Such an arrangement of the coaxial aperture 15 maximizes the intensity of the laser light incident on the coaxial aperture 15. Further, the side in the longitudinal direction of the opening 50 may be perpendicular to the active layer 23 as shown in FIG. Thereby, the direction of the coaxial opening 15 with respect to the recording track can be changed without changing the direction in which the laser 2 is attached to the optical head.
[0029]
According to the second embodiment described above, since the inside of the coaxial opening 15 is filled with the semiconductor laser material as in the first embodiment, the laser light is easily emitted from the coaxial opening 15. When a magnetic recording medium or the like used for an optical disk or hard disk is used for recording / reproduction, the longitudinal direction of the coaxial opening 15 may be parallel to the recording track. In recording on a magnetic recording medium used for an optical disk or a hard disk, recording is performed by modulating the magnetic field. Therefore, every time the magnetic field is reversed, recording is performed while the next mark is erased after the mark recorded immediately before that. Thus, the light utilization efficiency can be increased without substantially reducing the recording density.
[0030]
FIG. 3 shows a main part of a semiconductor laser according to the third embodiment of the present invention. In the third embodiment, in the first embodiment, a slope 50a is formed on the edge 4b on the opening 50 side of the metal light shield 4 and the edge 4b is tapered so as to spread toward the inside of the laser 2. An inclined surface 51a is formed around the central metal body 51 so that the periphery of the central metal body 51 is tapered toward the inside of the laser 2, and the others are configured in the same manner as in the first embodiment. Thereby, the condensing effect can be given to the edge 4b of the metal light shield 4 and the periphery of the central metal body 51, and the intensity of the laser beam from the coaxial opening 15 can be increased.
[0031]
4A and 4B show the main part of a semiconductor laser according to the fourth embodiment of the present invention. The fourth embodiment is the same as the first embodiment except that AlGaInP, which is a semiconductor material, is embedded in the coaxial opening 15 in the first embodiment.
[0032]
In the semiconductor laser 2 shown in FIG. 4A, the cleaved surface 26 of the laser crystal is etched by the FIB method to remove portions other than the donut-shaped opening 5a, and the removed portion is made of an insulating film made of a SiN film. A metal light-shielding body 4 made of Ag is deposited through a film 29, and the coaxial opening 15 and the metal light-shielding body 4 are made to be SiO 2. ₂ It is covered with an antireflection film 27 made of Further, the resonator of the laser 2 constitutes one resonator mirror by the metal light shield 4 and the highly reflective multilayer film 10b (not shown) on the rear end face.
[0033]
In the semiconductor laser 2 shown in FIG. 4B, a non-doped high resistance AlGaInP layer 29a is regrown on the cleaved surface 26, and portions other than the donut-shaped opening 5a of the AlGaInP layer 29a are removed by etching. The metal shading body 4 and the central metal body 51 are deposited on the removed portion.
[0034]
According to the fourth embodiment described above, since the semiconductor material AlGaInP having a high refractive index (about 3.5) is embedded in the coaxial aperture 15, the wavelength in this is shortened to 200 nm or less, and the coaxial aperture Coupling efficiency with 15 can be increased. Therefore, when the size of the opening 50 is 50 nm as in the first embodiment, the transmittance of the laser beam can be significantly increased. Further, since the coaxial opening 15 and the metal light-shielding body 4 are covered with the antireflection film 27, the ratio of reflection inside the resonator of the laser 2 can be reduced, the light utilization efficiency is improved, and the semiconductor crystal is deteriorated. Can be prevented.
[0035]
FIG. 5 shows a main part of a semiconductor laser according to the fifth embodiment of the present invention. The fifth embodiment is the same as the fourth embodiment except that a surface emitting semiconductor laser (VCSEL) 2 that performs laser oscillation perpendicular to the active layer is used as a semiconductor laser. The surface-emitting type semiconductor laser 2 includes a highly reflective multilayer film 10a, an n-type spacer layer 31, an AlGaInP active layer 32, a p-type AlAs layer 33, a spacer layer 34, and a high reflectance having a partial transmittance on a GaAs substrate 11. A multilayer film 10c and a phase adjustment layer 35 made of AlGaInP are sequentially stacked, and a portion of the phase adjustment layer 35 other than the doughnut-shaped opening 5a is removed by etching to form a p-type electrode 38, a metal light shield 4 and a central metal body 51. The surfaces of the coaxial opening 15 and the metal light shielding body 4 are covered with an antireflection film 39.
[0036]
The phase adjustment layer 35 has a thickness obtained by adding the thickness of the metal light shield 4 to a thickness of ¼ of the oscillation wavelength, and the etching depth is made equal to the thickness of the metal light shield 4. Thereby, the surface (output surface) 3 of the opening part 5a and the surface 4a of the metal light-shielding body 4 can be formed on the same plane. In addition, the phase adjustment layer 35 can make the phase of the reflection at the metal light shield 4 and the reflection at the highly reflective multilayer film 10b uniform, thereby achieving a high reflection of 99% or more. The opening 5a has a lower reflectance, and a relatively high intensity laser beam reaches the opening 5a. The wavelength of the laser light is shortened in inverse proportion to the refractive index of the phase adjustment layer 35, and is about 180 nm. For this reason, relatively strong propagating light can be generated even in the coaxial opening 15 having a side of 50 nm.
[0037]
FIG. 6 shows the coaxial opening 15. As shown in FIG. 6A, the coaxial opening 15 is provided at the center of the oscillation region 8 having a diameter of 3 μm, and the opening 50 has a square with a side of 50 nm. Further, when the oscillation region is narrowed to 1 μm or less, the ratio of light re-entering from the coaxial aperture 15 with respect to the light intensity in the resonator increases, and the self-coupling effect is enhanced, so that the SN of the reproduction signal is large. It is possible and suitable. However, in this case, the transverse mode of laser oscillation is the TEM01 mode as indicated by 40 in FIG. 4B, the center intensity is reduced, and the intensity is about the radius 1/2 of the oscillation region 8. For this reason, as shown in FIG. 4B, the aperture coaxial 15 can be set at a position shifted from the center by a distance of a radius ½, whereby generation of light from the coaxial aperture 15 can be maximized. In the TEM01 mode, since the oscillation intensity distribution is unstable, a portion for partially reducing the reflectivity may be provided on the output side of the resonator to fix the oscillation position.
[0038]
Next, an example of a method for manufacturing the surface emitting semiconductor laser 2 will be described. On the GaAs substrate 11, a highly reflective multilayer film 10a composed of an n-type AiGaP layer and an n-type GaInP layer having a quarter wavelength thickness, an n-type spacer layer 31, an AlGaInP active layer 32, a p-type AlAs layer 33, a spacer layer 34, a highly reflective multilayer film 10c made of a p-type AiGaP layer and a p-type GaInP layer having a quarter wavelength thickness, and a phase adjustment layer 35 made of AlGaInP are sequentially stacked by crystal growth, and then etched to form a port of the laser 2 The portions other than the portion 36 are removed, and the AlAs layer 33 is further oxidized from the surroundings by thermal oxidation using water vapor to form an AlOx layer 37. Since AiOx has a refractive index lower than that of the AlGaInP layer, a waveguide is formed, and since it is insulative, current confinement is also performed at the same time, whereby the oscillation region 8 can be formed. Thereafter, the phase adjustment layer 35 is removed by etching leaving the donut-shaped opening 5a and the electrode portion, and the p-type electrode 38, the metal light-shielding body 4, and the central metal body 51 are attached to the removed portion. In the case of a VCSEL, since the process can be performed in units of wafers without cleaving, the coaxial opening 15 can be formed using a photolithography process, but the FIB method may be used. Thereafter, an antireflection film 39 is deposited on the coaxial opening 15 and the surface 4 a of the metal light shield 4.
[0039]
According to the fifth embodiment described above, since the phase adjustment layer 35 made of AlGaInP having a high refractive index (about 3.5) is embedded in the coaxial aperture 15, the laser beam can be emitted efficiently. .
[0040]
FIG. 7 shows a disk device according to a sixth embodiment of the present invention. This disk device 100 rotates an optical disk 7 rotated by a rotating shaft 130, a suspension 133 that supports the same optical head 1 as that of the first embodiment so as to be rotatable around a rotating shaft 133a, and a suspension 133. And a rotary linear motor 143 to be moved.
[0041]
The optical disc 7 has a phase change recording medium made of GeSbTe. When the reflected light from the optical disk 7 is detected by the photodetector provided at the rear part of the semiconductor laser 2 by using the self-coupling effect of the semiconductor laser, the laser beam cannot be divided by the photodetector, so that a tracking error signal is formed. Uses the sample servo method. That is, a staggered mark (not shown) provided on the optical disc 7 is used, and a positional shift is detected from the magnitude of reflected light when the light spot passes through the left and right staggered marks.
[0042]
According to the sixth embodiment described above, the rotary linear motor 143 can be disposed outside the optical disk 7, so that the optical head 1 can be made thin and the entire disk device 100 can be downsized. This also allows the optical disc 7 to be rotated at a high speed (3600 rpm), and an average data transfer rate of 360 Mbps or higher is possible.
It is also possible to perform tracking in the high frequency region by attaching the semiconductor laser 2 to the flying slider via a piezoelectric element and applying a servo signal to the piezoelectric element.
In addition, a magnetic recording medium for a magnetic hard disk or a magneto-optical recording medium such as GaFeCo is used as a recording medium, and a GMR sensor (not shown) for detecting a signal by a magnetoresistive effect is attached to a slider to reproduce a recorded signal. It is also possible to do this. As a result, a high transfer rate for recording and reproduction can be achieved, and since the laser 2 is used only for recording and no re-incident light is used, it is possible to output recording laser light such as increasing the reflectance of the resonator. Can be optimized.
In the optical disk device 100, the semiconductor lasers of the second to fifth embodiments may be used.
[0043]
【The invention's effect】
As described above, according to the present invention, since the material having the laser beam transmissivity is embedded in the coaxial opening, the intensity of the laser beam incident on the recording medium can be greatly increased. Recording density can be increased, and miniaturization and improvement of the data transfer rate can be achieved.
[Brief description of the drawings]
FIG. 1A is a diagram showing an optical head according to a first embodiment of the present invention, and FIG. 1B is a diagram showing a main part of a semiconductor laser used therefor.
FIGS. 2A and 2B are diagrams showing a semiconductor laser according to a second embodiment of the present invention.
FIG. 3 is a view showing a main part of a semiconductor laser according to a third embodiment of the invention.
FIGS. 4A and 4B are diagrams showing a main part of a semiconductor laser according to a fourth embodiment of the present invention.
FIG. 5 is a diagram showing a semiconductor laser according to a fifth embodiment of the present invention.
FIGS. 6A and 6B are diagrams showing the positions of coaxial openings.
FIG. 7 is a perspective view showing an optical disc apparatus according to a sixth embodiment of the present invention.
FIG. 8 is a sectional view showing a conventional optical head.
FIG. 9 is a sectional view showing a conventional semiconductor laser.
FIGS. 10A and 10B are diagrams for explaining conventional problems.
FIG. 11 is a diagram showing the relationship between aperture size and optical output power
12A is a diagram showing a conventional semiconductor laser having a coaxial aperture, and FIG. 12B is a diagram showing the details of part A of FIG.
13 is a diagram showing problems of the semiconductor laser shown in FIG.
[Explanation of symbols]
1 Optical head
2 Semiconductor laser
3 Output surface of semiconductor laser
4 Metal shade
5a opening
5b TiO ₂ film
6 output laser light
7 Optical disc
7a Recording medium
7b substrate
8 Laser oscillation region
10a, 10c highly reflective multilayer film
10b Low reflection multilayer film
11 Levitation slider
15 Coaxial opening
20 Crystal part for semiconductor laser
21 Laser substrate
22 n-type cladding layer
23 Active layer
24 p-type cladding layer
25 Cap layer
26 Open face
27 Anti-reflective coating
28 Ridge
29 AiGaInP layer
31 Spacer layer
32 Active layer
33 AlAs layer
34 Spacer layer
35 Phase adjustment layer
36 Laser port
37 AlOx layer
38 p electrode
39 Anti-reflective coating
40 Transverse mode of semiconductor laser
50 openings
50a slope
51 Central metal body
51a slope
61 Light collector
61a Slope of light collector
62 Dielectric layer
63 Metal film
65 Micro coaxial body
66 Central Metal Body
100 disk unit
130 Rotating shaft
133 suspension
133a Rotating shaft
143 Rotary linear motor

Claims (19)

A metal light-shielding body in which a minute opening having a size of 100 nm or less and constituting a part of the resonator is formed on a flat surface located on the laser beam emission side;
A central metal body is provided at the center of the minute opening,
A semiconductor laser characterized in that a laser light transmitting material is embedded in the minute opening so as to be substantially the same surface as the surface of the metal light-shielding body .   2. The semiconductor laser according to claim 1, wherein the material constitutes a part of a semiconductor laser structure.   3. The semiconductor laser according to claim 2, wherein the semiconductor laser structure embedded in the minute opening is at least one of a reflection film, a multilayer reflection film, an active layer, a cladding layer, and a window material.   2. The semiconductor laser according to claim 1, wherein the material is an antireflection film.   The semiconductor laser according to claim 1, wherein the surface of the material is configured to be substantially flush with the surface of the metal light shield.   The semiconductor laser according to claim 1, wherein the material has an antireflection film formed on a surface thereof.   The semiconductor laser according to claim 1, wherein the minute opening has a rectangular shape.   2. The semiconductor laser according to claim 1, wherein the minute aperture has a rectangular shape whose long side is longer than ½ of the wavelength in the resonator.   The semiconductor laser according to claim 1, wherein the metal light shield has a tapered shape extending toward the inside of the laser at a peripheral portion of the minute opening.   The semiconductor laser according to claim 9, wherein the central metal body has a tapered shape that narrows toward the inside of the laser at a peripheral portion.   The semiconductor laser according to claim 1, wherein the semiconductor laser is an edge emitting semiconductor laser.   The semiconductor laser according to claim 1, wherein the semiconductor laser is a surface emitting semiconductor laser. The minute aperture, the surface-emitting type semiconductor laser center from the semiconductor laser of the radius of 1/2 as claimed in claim 12, wherein the structure formed on DoHanare position of the oscillating region of the oscillation region of. A metal light-shielding body having a minute aperture having a size of 100 nm or less constituting a part of the resonator is formed on a flat surface located on the laser beam output side, and a central metal body is provided at the center of the minute aperture. A semiconductor laser in which a laser light transmissive material is embedded in the minute opening so as to be substantially the same surface as the surface of the metal light-shielding body ,
An optical head, comprising: a flying slider that holds the semiconductor laser and floats on an optical disk.   15. The optical head according to claim 14, wherein the minute opening has a rectangular shape whose longitudinal direction is perpendicular to the recording track of the optical disc.   15. The optical head according to claim 14, wherein the minute opening has a rectangular shape whose longitudinal direction is parallel to the recording track of the optical disc.   The optical head according to claim 14, wherein the semiconductor laser is attached to a rear end portion of the flying slider. An optical disc on which a recording medium is formed;
A metal light-shielding body having a minute aperture having a size of 100 nm or less constituting a part of the resonator is formed on a flat surface located on the laser beam output side, and a central metal body is provided at the center of the minute aperture. A semiconductor laser in which a laser light-transmitting material is embedded in the minute opening so as to be substantially the same surface as the surface of the metal light-shielding body, and holding the semiconductor laser and flying above the optical disk An optical disk apparatus comprising an optical head having a flying slider. Preparing a semiconductor laser material having a laser beam output surface;
By the portions excluding the donut-like region set in the laser light output surface on a recess by etching, depositing a metal member by a photolithography process or a focused ion beam method in the recess, claim 1 A method for manufacturing a semiconductor laser, comprising: manufacturing the semiconductor laser according to 1).

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