KR20020051213A - Near-field optical data storage head minimized by using SIL - Google Patents

Abstract

PURPOSE: A micro near-field optical data storage head using an SIL(Solid Immersion Lens) is provided to use the SIL for a big size lens, and to use diffraction elements for the rest parts, thereby minimizing the size. CONSTITUTION: An optical waveguide(201) has a plane shape. At least more than one condensing diffraction grating(203) is attached to one of both sides of the optical waveguide, and changes a path of an incident light(202) to an SIL(205). More than one optical division diffraction grating(210) is located between a light source and the condensing diffraction grating, and changes a path of a signal light(209). The SIL is composed of a curved part and a plane part, and concentrates the incident light on one point of the plane part. A coil(206) is attached to an option position of an optical storage head, and generates a magnetic field. The curved part of the SIL is formed on a sphere, hemisphere, or super-hemisphere, to make the incident light diffracted by the condensing diffraction grating form an optical point less than diffraction limits.

Description

Near-field optical data storage head minimized by using SIL

The present invention is an ultra-small near field optical information storage head using SIL (Solid Immersion Lens), particularly in the optical information storage device for recording and reproducing information on the recording medium using the slide head to increase the recording density, connection speed and mobility Relates to a micro head.

In an optical storage device that focuses a laser beam at a point on a recording medium having magneto-optical or phase shift characteristics and stores information, recording and reproduction characteristics are determined by a head. The optical storage head has been developed in the direction of increasing the recording density, speeding up the connection speed, and increasing the mobility, and is now miniaturized, lightweight, and high performance.

In order to increase the recording density, the size of the light spot focused on the recording medium must be reduced, but the size of the focused light spot cannot be reduced below a certain size at a given wavelength due to the diffraction limit of light. Therefore, techniques for overcoming these limitations and increasing storage density include DVD and near field recording technology. DVD technology is a method of forming multiple layers of media in a storage medium and changing the focal length of the focused light so that the focused light can be focused on each layer. However, this method does not fundamentally increase the storage density, there is a problem that can not significantly increase the transmission speed.

Near field optical recording technology is largely divided into aperture type and SIL type. The aperture method forms a small aperture below the diffraction limit, closes the distance between the aperture and the recording medium to several tens of nm or less, and passes the light through the aperture. The optical energy distribution of the aperture is recorded without being affected by diffraction as much as the aperture size. The way it is delivered to the medium. The material used as an opening is an optical fiber, which makes an opening of several tens of nm or less at the end of a pointed optical fiber coated with a metal film, and transmits light to record information. However, the opening method has a disadvantage in that the amount of light exiting the opening is extremely small and thus it is difficult to obtain the amount of optical energy required for actual recording.

On the other hand, the SIL method uses the principle that when light is focused into a medium having a high refractive index, the wavelength is reduced and the angle of refraction is increased so that the light is focused inside the hemispherical SIL medium and the size of the focused light spot is reduced below the diffraction limit. And the flat bottom surface of the SIL is close to the recording medium and the light is focused on a plane inside the SIL medium. The focused light forms light spots of short wavelength and high NA (Numerical Aperture) due to the high refractive index of the SIL medium, and the light on the recording medium is very close to the SIL because the energy of these light spots is hardly affected by diffraction. This is delivered and the information is recorded. In order to access and transmit information more quickly using this method, a flying head method adopted in the existing hard disk has been proposed and studied. However, this method has a limitation in commercialization in terms of volume and weight because the slide head configuration is a combination of several reflectors and lenses.

Therefore, the ultra-small near field optical information storage head using the SIL according to the present invention, which is designed to solve the above problems, incorporates the conventional near field recording method using the SIL to the waveguide diffraction grating, so that the lens occupying a large volume is only SIL. Its purpose is to provide a reduced optical storage head device by minimizing volume by using a diffraction element.

1 is a schematic diagram of an optical storage device using an ultra-small near field optical information storage head according to an embodiment of the present invention;

2 is an explanatory diagram for explaining the principle of the sliding head 104 of the optical storage device according to the present invention.

3 is a plan view of the slide head according to the present invention.

※ Explanation of code for main part of drawing ※

201: waveguide 202: incident light

203: light diffraction grating 204: diffraction light

205: solid immersion lens (SIL) 206: coil

207: recording medium 208: disk substrate

209: signal light 210: light splitting diffraction grating

211: recording light

Miniature near field optical data storage head using the SIL according to the present invention for achieving the above object is a planar optical waveguide; One or more condensing diffraction gratings attached to one surface of both surfaces of the optical waveguide to change a path of incident light to a solid immersion lens (SIL); At least one light splitting diffraction grating positioned between a light source and the focusing diffraction grating to change a path of signal light; The SIL having a curved portion and a flat portion to collect the incident light at a point of the flat portion; And a coil attached to an arbitrary position within the optical storage head to generate a magnetic field.

In addition, the first step of the incident light is traveling along the waveguide 201 having a focusing diffraction grating; A second step of diffracting the incident light by the condensing diffraction grating and condensing on the bottom surface of the SIL; A third step of heating a specific domain of the magneto-optical recording medium coated on the disk substrate adjacent to the focused incident light above a Curie temperature; And a fourth step of recording the information by changing the magnetization of the domain by the magnetic field of the coil in the specific domain heated to the high temperature.

In addition, the first step of the incident light incident on the same path as when recording the information is polarized by interacting with the recording medium; A second step in which the polarized incident light is incident on an optical waveguide through a focusing diffraction grating; A third step of transmitting the polarized incident light incident on the optical waveguide to a photo detector by a light splitting diffraction grating on the optical waveguide; And a fourth step of reproducing the information of the recording medium by detecting the degree of polarization of the signal light by the photo detector.

Hereinafter, an embodiment of the ultra-small near field optical information storage head using the SIL according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of an optical storage device using an ultra-small near field optical information storage head according to an embodiment of the present invention, wherein the optical storage device includes a disc recording medium 101, a rotating arm 102, a rotating shaft 103, And a slide head 104. The optical storage device records and reproduces information while flying at a constant height in close proximity to the microscopic near-field slide head 104 attached to the end of the rotating arm 102 above the disk recording medium 101 like a conventional hard disk. The connection of information is performed while the rotating arm 102 rotates about the rotation axis 103.

2A and 2B illustrate the principle of the slide head 104 of the optical storage device according to the present invention, wherein the slide head 104 includes a waveguide 201, incident light 202, and diffracted light 204. , Condensing diffraction grating 203, diffraction light 204, SIL 205, coil 206, magneto-optical recording medium 207, disk substrate 208, signal light 209, light splitting diffraction grating 210 ) And the recording light 211.

First, the action of the slide head 104 is divided into recording and reproducing information. When recording the information, the incident light 202 proceeds along the waveguide 201 where the condensing diffraction grating 203 is located and then condenses. The diffracted grating 203 is diffracted and focused on the bottom surface of the SIL 205, and the collected recording light 211 is directed to a specific domain of the magneto-optical recording medium 207 coated on the disk substrate 208 in close proximity. The information is recorded by making the high temperature (above the Curie temperature of the recording medium) and changing the magnetization of the domain raised to a high temperature by a magnetic field generated when a current flows in the coil 206.

At this time, the position of the SIL 205 depends on the characteristics of the condensing diffraction grating 203, and the path of the incident light 202 is changed perpendicularly to the plane of the condensing diffraction grating 203. In FIG. 2A, the light diffraction grating 203 is positioned parallel to the light converging surface of the SIL 205, but the incident light 202 forms an incident light at a constant angle with the plane of the light diffraction grating 203. In the case where the path of 202 is changed (FIG. 2B), the line of focus of the light diffraction grating 203 and the diffraction light 204 is focused so that the incident light 202 is focused at the center of the planar portion of the SIL 205. SIL 205 is positioned so that the center of SIL 205 coincides with. In any of the above cases, the plane of the diffraction grating is positioned so that the planar portions of the recording medium 207 and the SIL 205 are parallel to each other.

3 is a plan view of the slide head according to the present invention. Referring to FIG. 3, first, recording of information is performed by the incident light 303 emitted from the light source 302 traveling through the waveguide 301 and passing through the condensing diffraction grating 305 into the SIL 306. The magnetic field generated when current flows in the coil 307 is performed by changing the magnetic state of the recording medium 207 in proximity to the portion where the light is collected. Therefore, the coil 307 should be located where the magnetic flux generated by the coil 307 can generate magnetic flux perpendicular to the recording medium 207 so that the magnetization of the recording medium 207 can be changed.

Also, the reproduction of the information is performed by the incident light 303 emitted from the light source 302 being detected by the photo detector 310 after being polarized in interaction with the recording medium 207. In other words, when the information is reproduced, the incident light 303 incident on the same path as when recording is polarized by interacting with the recording medium 207, and the polarized incident light 303 is focused on the condensed diffraction grating 305. Is incident on the optical waveguide 301, and the polarized incident light 303 is transmitted to the photodetector 310 by the light splitting diffraction grating 304 on the waveguide 301. The polarization degree of the signal light 309 is detected to reproduce the information of the recording medium 207. Herein, the signal light 309 refers to the light transmitted through the light splitting diffraction grating 304 to the photo detector 310 through the polarized incident light 303.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, in the present invention, a small-size optical storage head device having a small volume by using a SIL and a diffractive element for a lens occupying a large volume by applying a near field recording method using SIL to a waveguide diffraction grating is used. Implemented. In addition, since the ultra-compact optical storage head according to the present invention has a high information connection rate and uses a near field method, there is an advantage of increasing the information storage density by forming a light spot below the diffraction limit.

Claims (9)

An optical storage head device capable of storing information in an optical recording medium, Planar optical waveguides; One or more condensing diffraction gratings attached to one surface of both surfaces of the optical waveguide to change a path of incident light to a solid immersion lens (SIL); At least one light splitting diffraction grating positioned between a light source and the focusing diffraction grating to change a path of signal light; The SIL having a curved portion and a flat portion to collect the incident light at one point of the flat portion; And And a coil attached to an arbitrary position within the optical storage head to generate a magnetic field. The method of claim 1, The SIL is, The curved portion of the SIL is composed of a sphere, a hemisphere or a super-hemisphere so that the light diffracted by the condensing diffraction grating can form a light spot below a diffraction limit. Optical storage head device. The method of claim 1, When the incident light diffracted in the condensing grating grating is changed in the path of the incident light perpendicular to the plane forming the condensing grating grating, The optical storage head device, characterized in that the diffraction grating and the SIL is configured to be parallel to the condensing surface of the SIL. The method according to claim 1 or 3, When the incident light diffracted by the condensing diffraction grating is at a predetermined angle not perpendicular to the plane of the condensing diffraction grating and the path of the incident light is changed, And the center of the SIL coincides with the center of the condensed diffraction grating surface and the line of diffraction light so that the incident light is focused at the center of the planar portion of the SIL. The method according to claim 1 or 3, And the condensing diffraction grating plane is positioned so that the planar portion of the recording medium and the SIL are parallel to each other. The method of claim 1, And the coil is positioned where magnetic flux generated by the coil can generate magnetic flux perpendicular to the recording medium so as to change the magnetization of the recording medium. The method according to claim 1 or 5, And the coil is configured to be positioned between the condensing diffraction grating and the SIL. A first step in which incident light travels along a waveguide with a focusing diffraction grating; A second step of diffracting the incident light by the condensing diffraction grating and condensing on the bottom surface of the SIL; A third step of heating a specific domain of the magneto-optical recording medium coated on the disk substrate adjacent to the focused incident light above a Curie temperature; And And a fourth step of recording the information by changing the magnetization of the domain by the magnetic field of the coil in the specific domain heated to the high temperature. A first step in which incident light incident on the same path as when recording information is polarized by interacting with the recording medium; A second step in which the polarized incident light is incident on an optical waveguide through a focusing diffraction grating; A third step of transmitting the polarized incident light incident on the optical waveguide to a photo detector by a light splitting diffraction grating on the optical waveguide; And And a fourth step of detecting the polarization degree of the signal light by the photo detector to reproduce the information of the recording medium.