JP2005228385A - Near-field light probe, manufacturing method of near-field light probe, and optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a near-field light probe of which an assembling work with a slider is not needed with a simple constitution. <P>SOLUTION: An optical fiber 3 is fixed on a ferrule 2 which is used for an optical fiber connector, and the tip part of a core 31 of the optical fiber 3 fixed to the ferrule 2 is pointed, and a minute aperture 4 at the tip of the core 31 is formed by coating the pointed tip part of the core 31 and the tip part of a clad 32 with a light shielding film 5 to make them be aligned with the tip surface of the ferrule 2, then the minute aperture 4 generating the near-field light is accurately made to be aligned with the tip surface of the ferrule 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a near-field optical probe that records or reproduces information on a recording medium using near-field light, a method for manufacturing the near-field optical probe, and an optical pickup.

  An information recording / reproducing apparatus currently in practical use for recording and reproducing information to and from an optical memory such as an optical disk records a laser beam condensed to the diffraction limit of light determined by the wavelength of the light and the numerical aperture of the objective lens. Information is recorded by irradiating the medium and applying thermal / magnetic modulation to the recording layer, and detecting reflected light intensity and polarization modulated by the recording pits on which the information is recorded, thereby reproducing the information. When this information recording / reproducing apparatus is used, the recording density of the optical memory is determined by the diffraction limit of light, and there is a limit to cope with the increase in the amount of information surrounding information devices such as computers in recent years. There is a demand for a large-capacity optical memory that achieves a recording density that exceeds the diffraction limit of light.

  As such a large-capacity optical memory, an information recording / reproducing apparatus using so-called near-field light that records and reproduces information using near-field light has been proposed in, for example, Patent Document 1 and Patent Document 2. Near-field means that light incident from one of two media with different refractive indexes above the total reflection condition is totally reflected at the reflection boundary surface, but only a non-propagating electromagnetic field component oozes out partially across the boundary surface. This is a non-propagating electromagnetic field region. This near field is said to ooze out only in the vicinity of an aperture that is smaller than the wavelength of incident light, and has a lateral extent that is almost the same as the aperture size. Therefore, the resolution exceeding the diffraction limit of light can be obtained by reducing the aperture size.

  In the optical system of the information recording / reproducing apparatus using near-field light, as shown in FIG. 10, the laser light emitted from the semiconductor laser element (LD) 21 is converted into parallel light by the collimator lens 22, and this light is polarized beam splitter. 23 and the quarter-wave plate 24, and then collected by the objective lens 25 and applied to the near-field optical probe 50. The near-field optical probe 50 is provided with a frustoconical protrusion formed of a high refractive material such as silicon having a refractive index higher than that of a light transmitting substrate on a light transmitting substrate such as a glass substrate. Formed by coating with a metal such as silver or aluminum, or as shown in Patent Document 1 or Patent Document 2, the tip of the optical fiber is sharpened to form a metal light-shielding film, and a minute opening is formed at the tip. Is formed. Then, the light collected by the objective lens 25 is converted into near-field light of a minute size at the tip of the near-field light probe 50. With this converted near-field light, information is recorded on a recording layer provided on the surface of the recording medium 11 facing the near-field optical probe 50, and recording is performed at a higher density than when the object lens 25 is simply focused. Can be realized. When reproducing information recorded on the recording medium 11, the light reflected from the recording layer passes through the objective lens 25 and the quarter wavelength plate 24, is reflected by the polarizing beam splitter 23, and is detected by the condenser lens 29. The light is condensed on the detector 27, the light intensity is detected by the photodetector 27, and the information is reproduced.

  In the method of manufacturing a near-field optical probe formed by sharpening the tip of an optical fiber shown in Patent Document 1 or Patent Document 2, the optical fiber is cleaved so that the end face is perpendicular to the extending direction of the optical fiber. After that, the tip is etched with buffered hydrofluoric acid. When this etching is performed, the core at the tip of the optical fiber is doped with an impurity different from that of the cladding, so that the etching rate is slow and only the core is sharpened. Thereafter, a metal light-shielding film is formed on the sharpened core and clad ends, and the tip of the optical fiber is cut in parallel with the cleavage plane to form a near-field optical fiber probe having a desired opening diameter.

In order to perform recording / reproduction by generating near-field light with this near-field optical fiber probe, it is necessary to mount the near-field optical fiber probe on a slider. When recording / reproducing using near-field light, the distance between the slider and the surface of the recording medium is about 10 nm. Therefore, the bottom surface of the slider and the tip of the near-field optical fiber probe having the minute aperture must be assembled with a precision of 5 nm or less at the maximum. As described above, it has been difficult to assemble the bottom surface of the slider and the tip of the near-field optical fiber probe with high accuracy.
JP 2001-34979 A JP 2001-34980 A

An object of the present invention is to provide a near-field optical probe and a method for manufacturing a near-field optical probe that improve such disadvantages and do not require assembly with a slider with a simple configuration.
It is another object of the present invention to provide an optical pickup in which the actuator and the control system for aligning the optical system and the near-field optical probe are not required, and the apparatus is miniaturized and simplified.

  The near-field optical probe of the present invention includes a ferrule used for an optical fiber connector, an optical fiber fixed at the center of the ferrule and having a sharpened tip end of the core, and a sharpened core of the optical fiber. And a light-shielding film having a minute opening formed at the tip of the core.

  A second near-field optical probe according to the present invention includes a slider, an optical fiber fixed to the slider and having a sharpened tip of the core, a sharpened core tip of the optical fiber, and a clad tip. And a light-shielding film having a minute opening formed at the tip of the core.

  In the method of manufacturing a near-field optical probe according to the present invention, an optical fiber is bonded and fixed to a ferrule used for an optical fiber connector, and after polishing the ferrule and the tip of the optical fiber, the ferrule and the tip of the optical fiber are etched. The optical fiber is retracted into the ferrule to sharpen the core tip of the optical fiber, and a metal light-shielding film is formed on the sharpened core and the end of the clad. Fill the hole with a cured resin to form a filling layer, polish the tip of the ferrule, the filling layer, and the tip of the light shielding film covering the sharpened core, and polish the tip of the core, so that a minute opening is formed at the tip of the core It is characterized by forming.

  According to a second method of manufacturing a near-field optical probe of the present invention, an optical fiber is bonded and fixed to a slider, and the slider and the tip of the optical fiber are polished. The tip of the core of the optical fiber is sharpened by retreating into the inside, a metal light-shielding film is formed on the sharpened core and the end of the clad, and the resin is cured in the hole at the tip of the slider formed by the receding of the optical fiber To form a filling layer, and polish the tip of the slider, the filling layer, and the tip of the light shielding film covering the sharpened core and the tip of the core to form a micro opening at the tip of the core. It is characterized by.

  In the optical pickup of the present invention, the near-field optical probe is attached to the near-field optical probe on a surface opposite to the near-field optical probe of the arm that is moved by the arm motor, and is used for recording, reproduction, or recording. An optical system for irradiating light for reproduction is mounted.

  The second optical pickup according to the present invention is configured such that the near-field optical probe is attached to the near-field optical probe on a surface opposite to the near-field optical probe of the arm that is moved by an arm motor and is attached to the near-field optical probe. An optical system for irradiating light for reproduction or recording / reproduction, and condensing means for deflecting the light emitted from the optical system and condensing it on the near-field optical probe are mounted.

  Further, the second optical pickup is provided with a focusing unit that deflects and collects the light emitted from the optical system on the incident surface of the recording, reproducing, or recording / reproducing light of the near-field optical probe. It is desirable to have a second light collecting means for collecting light.

  The present invention fixes an optical fiber to a ferrule or slider used in an optical fiber connector, sharpens the core tip of the optical fiber fixed to the ferrule or slider, and sharpens the tip of the core and the tip of the clad. Covering with a light-shielding film and forming the minute opening at the tip of the core by matching with the tip surface of the ferrule or slider, it is possible to match the tip of the ferrule or slider with the minute opening that generates near-field light with high accuracy. In addition, information can be stably recorded on the recording medium, and information recorded on the recording medium can be stably reproduced.

  Further, an optical system for irradiating the near-field light probe with light for recording or reproduction or recording / reproduction on the surface opposite to the near-field light probe of the arm attached with the near-field light probe via the suspension, Optical pickup can be assembled with high accuracy by mounting the optical system and the light collecting means that deflects the light emitted from the optical system and concentrates it on the near-field optical probe, and can record and reproduce stably. In addition, the apparatus can be miniaturized.

  Further, a second collection for condensing the light from the condensing means for deflecting and condensing the light emitted from the optical system on the incident surface of the recording or reproducing or recording / reproducing light of the near-field optical probe. By providing the light means, the numerical aperture (NA) of the objective lens system can be increased, and the diameter of the focused spot with respect to the near-field optical probe can be reduced to increase the light utilization efficiency.

  FIG. 1 is a cross-sectional view showing a configuration of a near-field optical probe (hereinafter referred to as an optical probe) according to the present invention. As shown in the figure, the optical probe 1 is used for an optical fiber connector, and is made of, for example, zirconia, and is fixed to the central portion of the ferrule 2, which is a mainly cylindrical member that holds and fixes the optical fiber at the central portion. The optical fiber 3 with the tip of the core 31 sharpened, the tip of the core 31 with the sharpened optical fiber 3 and the tip of the clad 32 are covered, and the minute opening 4 is formed at the tip of the core 31 And a filling layer 6 formed of an adhesive between the hole at the tip of the ferrule 2 and the light shielding film 5.

  When the optical fiber 1 is manufactured, an adhesive is put between the inner peripheral surface of the hole at the center of the ferrule 2 and the outer peripheral surface of the optical fiber 3 as shown in the process diagram (a) of FIG. The optical fiber 3 is bonded and fixed to. Thereafter, the ferrule 2 and the tip of the optical fiber 3 are polished by a polishing machine. When polishing the ferrule 2 and the tip of the optical fiber 3, as shown in FIG. 2, it may be polished in an arc shape or may be polished flat. After the tips of the ferrule 2 and the optical fiber 3 are polished, the tips of the ferrule 2 and the optical fiber 3 are immersed in buffered hydrofluoric acid, and the tip of the optical fiber 3 is etched. By this etching, as shown in FIG. 2B, the optical fiber 3 is retracted into the ferrule 2 and the tip of the core 31 is sharpened. Thereafter, as shown in FIG. 2C, a metal light-shielding film 5 is formed on the sharpened ends of the core 31 and the clad 32 by sputtering or the like. Next, as shown in FIG. 2 (d), the hole at the tip of the ferrule 2 formed by retreating the optical fiber 3 is filled with an ultraviolet curable adhesive or a two-component epoxy adhesive and cured to be filled. 6 is formed. After forming the filling layer 6, the tip of the ferrule 2 and the filling layer 6 are polished by a polishing machine, and at the same time, the tip of the light shielding film 5 and the tip of the core 31 covering the sharpened core 31 of the optical fiber 3 are covered. The optical probe 1 is manufactured by polishing to a desired position and forming the micro-opening 4 at the tip of the core 31 as shown in FIG. In this way, the minute opening 4 at the tip of the core 31 can be formed so as to coincide with the tip surface of the ferrule 2.

  By using the ferrule 2 itself as a slider, the optical probe 1 can make the bottom surface of the slider coincide with the minute opening 4 of the optical probe 1 with high accuracy, and information can be stably recorded on a recording medium. At the same time, the information recorded on the recording medium can be stably reproduced.

  In the above description, the case where the ferrule 2 itself is used as a slider has been described. However, the optical probe may be formed by directly fixing the optical fiber 3 to the slider.

  The optical probe 1a formed by directly fixing the optical fiber 3 to the slider is formed of ceramics or the like as shown in the cross-sectional view of FIG. 3, and includes a slider 7 having a through hole 71 through which the optical fiber 3 passes, and a slider 7 The optical fiber 3 is fixed to the through-hole 71 and the tip of the core 31 is sharpened; the tip of the core 31 of the optical fiber 3 that is sharpened and the tip of the clad 32 are covered; And a light-shielding film 5 having a minute opening 4 formed thereon, and a filling layer 6 formed of an adhesive between the hole at the tip of the ferrule 2 and the light-shielding film 5.

  When the optical fiber 1a is manufactured, an adhesive is put between the inner peripheral surface of the through hole 71 of the slider 7 and the outer peripheral surface of the optical fiber 3 as shown in the process diagram (a) of FIG. The optical fiber 3 is bonded and fixed to. Thereafter, the slider 7 and the tip of the optical fiber 3 are polished by a polishing machine. After polishing the slider 7 and the tip of the optical fiber 3, the tip of the slider 7 and the optical fiber 3 is immersed in buffered hydrofluoric acid, and the tip of the optical fiber 3 is etched. By this etching, as shown in FIG. 4B, the optical fiber 3 is retracted into the through ferrule 2 of the slider 7 and the tip of the core 31 is sharpened. Thereafter, as shown in FIG. 4C, a metal light-shielding film 5 is formed on the sharpened ends of the core 31 and the clad 32 and the tip of the slider 7 by sputtering or the like. Next, as shown in FIG. 4 (d), the through hole 71 of the slider 7 in which the optical fiber 3 is retracted and opened is filled with an ultraviolet curable adhesive or a two-component epoxy adhesive and cured to be filled. 6 is formed. After forming the filling layer 6, the tip of the slider 7 and the filling layer 6 are polished by a polishing machine, and at the same time, the tip of the light shielding film 5 and the tip of the core 31 covering the sharpened core 31 of the optical fiber 3 are covered. Polishing to a desired location and forming the micro-opening 4 at the tip of the core 31 as shown in FIG. In this way, the minute opening 4 at the tip of the core 31 can be formed so as to coincide with the tip surface of the slider 7.

  An overall configuration of an optical pickup 10 using the optical probe 1 or the optical probe 1a is shown in a perspective view of FIG. On the recording medium 11, either the optical probe 1 or the optical probe 1 a that generates near-field light (hereinafter referred to as an optical probe 1) is disposed, and the optical probe 1 is generated by an air flow generated by the rotation of the recording medium 11. Floats several tens of nanometers from the surface of the recording medium 11 or slides in contact. The optical probe 1 is connected to an arm 13 via a suspension 12. An optical system 14 is mounted on the arm 13. As shown in FIG. 6, the optical system 14 includes a semiconductor laser element 21, a collimator lens 22, a polarizing beam splitter 23, a quarter wavelength plate 24, an objective lens 25, a condenser lens 26, and a photodetector 27. Light is incident on the optical probe 1 and the reflected light from the recording medium 11 is detected. As shown in the cross-sectional view of FIG. 7, the arm 13 corresponding to the optical path between the optical system 14 and the optical probe 1 has a hole or is fitted with a translucent material such as glass. Yes.

  The arm 13 is moved by an arm motor 15. The movement of the arm 13 moves the optical probe 1 onto a desired track on the recording medium 11, and the mounted optical system 14 and the optical probe 1 also move together. Therefore, since the laser beam automatically emitted from the optical system 14 is irradiated onto the optical probe 1, it is not necessary to provide an actuator or a control system for aligning the optical system 14 and the optical probe 1, and the optical pickup 10 can be made with high accuracy. As a result, the apparatus can be assembled, recording and reproduction can be performed stably, and the apparatus can be downsized.

  The light emitted from the semiconductor laser element 21 of the optical system 14 passes through the collimator lens 22, the polarization beam splitter 23, the quarter wavelength plate 24, and the objective lens 25 and is collected on the core 31 of the optical probe 1. The light coupled to the core 31 of the optical probe 1 propagates through the core 31 and generates near-field light from the minute opening 4 with a sharp tip. Thereby, the light that excited the recording medium 11 generates a near field according to the state of the recording medium 11. The generated near field is coupled into the core 31 through the minute opening 4 at the tip of the optical probe 1, propagates in the opposite direction to the incident light and enters the optical system 14, and the objective lenses 25 and 1 of the optical system 14. The information on the recording medium 11 is read by being detected by the photodetector 27 through the / 4 wavelength plate 24, the polarizing beam splitter 23, and the condenser lens 26.

  In the optical pickup 10 described above, light is directly incident on the optical probe 1 from the optical system 14 and reflected light from the recording medium 11 is directly incident on the optical system 14 from the optical probe 1. As shown in FIG. 3, the arm 13 includes a semiconductor laser element 21, a collimator lens 22, a polarizing beam splitter 23, a quarter-wave plate 24, a condensing lens 26, and an optical system 14a having a photodetector 27, a deflector 16, and a collector. The optical pickup 10a may be configured by mounting the optical element 17. Light from the optical system 14 enters the optical probe 1 through the deflector 16 and the condensing element 17, and reflected light from the recording medium 11 that has passed through the optical probe 1 is optically transmitted through the condensing element 17 and the deflector 16. Light is received by the system 14a. By mounting the optical system 14a, the deflector 16 and the light condensing element 17 on the arm 13 in this way, the optical pickup 10a can be assembled with high accuracy, and recording and reproduction can be performed stably. Can be miniaturized.

  As the condensing element 17 of the optical pickup 10a, a reflective objective lens 171 is used as shown in FIG. 9A, or a right-angle prism 172 and a right-angle prism 172 as shown in FIG. 9B. The condensing element 17 may be constituted by an objective lens 173 formed of a material having a higher refractive index than that of the material constituting the right-angle prism 172.

  Further, as shown in FIGS. 9C and 9D, the objective lens 173 may be provided on the upper surface of the optical probe 1, and the condensing element 17 may be constituted by a right-angle prism 172 or a reflective objective lens 171.

  9C, when the objective lens 173 is provided on the upper surface of the optical probe 1 and the right-angle prism 172 is used as the light condensing element 17, the light from the optical system 14a remains as parallel light from the right-angle prism 172. The objective lens 173 on the optical probe 1 can be irradiated, and the accuracy required for alignment between the irradiated light and the optical probe 1 is relaxed. Therefore, the alignment between the light collected on the core 31 of the optical probe 1 and the optical probe 1 is determined by the positional relationship between the objective lens 173 and the optical probe 1. The positional relationship between the lens 173 and the optical probe 1 does not change, and recording and reproduction can be performed stably.

  Further, as shown in FIG. 9D, an objective lens 173 is provided on the upper surface of the optical probe 1, a reflective objective lens 171 is used as the condensing element 17, and a reflective objective lens 171 and an objective are used as the objective lens system. By using two of the lenses 173, it is possible to increase the numerical aperture (NA) of the objective lens system, and it is possible to increase the light utilization efficiency by reducing the diameter of the focused spot with respect to the optical probe 1.

It is sectional drawing which shows the structure of the 1st optical probe of this invention. It is process drawing which shows the manufacturing method of a 1st optical probe. It is sectional drawing which shows the structure of the 2nd optical probe of this invention. It is process drawing which shows the manufacturing method of the 2nd optical probe. It is a perspective view which shows the structure of the 1st optical pick-up of this invention. It is a block diagram of an optical system. It is sectional drawing which shows the structure of a 1st optical pick-up. It is a perspective view which shows the structure of the 2nd optical pick-up of this invention. It is sectional drawing which shows the structure of a 2nd optical pick-up. It is a block diagram of a prior art example.

Explanation of symbols

1; optical probe, 2; ferrule, 3; optical fiber, 31; core, 32;
4; micro opening, 5; light shielding film, 6; filling layer, 7; slider, 10; optical pickup,
11; Recording medium, 12; Suspension, 13; Arm, 14; Optical system,
15; arm motor, 16; deflector, 17; condensing element.

Claims (7)

  A ferrule used for an optical fiber connector, an optical fiber fixed to the center of the ferrule and having a sharpened tip of the core, a sharpened core tip of the optical fiber and a clad tip A near-field optical probe comprising: a light-shielding film that is covered and has a microscopic opening formed at a tip of the core.   A slider, an optical fiber fixed to the slider and having a sharpened tip of the core, a sharpened core tip of the optical fiber, and a clad tip, and a small opening at the core tip A near-field optical probe, comprising:   After fixing the optical fiber to the ferrule used for the optical fiber connector and polishing the ferrule and the tip of the optical fiber, the ferrule and the tip of the optical fiber are etched to retract the optical fiber into the ferrule and Sharpens the core tip, forms a metal light-shielding film on the sharpened core and clad ends, fills the hole at the tip of the ferrule formed by the receding optical fiber, and forms a filling layer And a tip of the light shielding film covering the tip of the ferrule, the filling layer, and the sharpened core and the tip of the core are polished to form a micro-opening at the tip of the core. Manufacturing method.   After fixing the optical fiber to the slider and polishing the slider and the tip of the optical fiber, the slider and the tip of the optical fiber are etched to retract the optical fiber into the slider, sharpening the core tip of the optical fiber, A metal light-shielding film is formed on the sharpened core and clad ends, and a filling layer is formed by filling the hole at the tip of the slider formed by the receding optical fiber with a hardened resin. A method of manufacturing a near-field optical probe, comprising: polishing a tip of a light-shielding film covering a layer and a sharpened core and a tip of the core to form a microscopic opening at the tip of the core.   A near-field optical probe according to claim 1 or 2 is attached via a suspension, and the near-field optical probe is used for recording or reproducing on the opposite surface of the arm that is moved by an arm motor, facing the near-field optical probe. An optical pickup equipped with an optical system for irradiating light for recording and reproduction.   A near-field optical probe according to claim 1 or 2 is attached via a suspension, and the near-field optical probe is used for recording or reproducing on the opposite surface of the arm that is moved by an arm motor, facing the near-field optical probe. An optical pickup comprising: an optical system for irradiating light for recording / reproducing; and a condensing means for deflecting the light emitted from the optical system and condensing it on the near-field optical probe. A second collection for condensing the light from the condensing means for deflecting and condensing the light emitted from the optical system on the incident surface of the recording, reproducing or recording / reproducing light of the near-field optical probe. 7. The optical pickup according to claim 6, further comprising optical means.

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