Optical data storage system

An optical data storage system includes a light emitting and receiving device (30), a light transmission device (31) having an input port (32) and an output port (33). The input port is disposed adjacent to the light emitting and receiving device. Furthermore, a micro window is provided at the output port, and a diameter of the micro window is in a range of 5 to 70 nanometers. Therefore, in the optical data storage system, the spot size of the light beams is close to the diameter of the micro window. Accordingly, the size of the beam spot is small enough to write information at a higher density with respect to an optical storage medium.

BACKGROUND

1. Field of the Invention

The present invention relates to an optical data storage system, and more particularly to a near-field optical data storage system which can write or read information at high density with respect to an optical storage medium.

2. General Background

An optical data storage system mainly includes an optical pickup and a near-field. The optical pickup has a solid immersion optical system or a solid immersion lens. The near-field is provided between the solid immersion optical system or solid immersion lens and the optical data storage medium. The optical pickup using the near-field performs writing and/or reading of information with respect to the optical data storage medium.

Referring toFIG. 4, a conventional optical data storage system includes a light transmission and reception portion20, a reflective mirror22, a focusing objective lens24, and a refractive solid immersion lens26supported by a slider28. The optical storage medium18includes a substrate181, a protective layer183, and a recording layer (not shown) between the substrate181and the protective layer183. The slider28aerodynamically floats the solid immersion lens26, whereby an air gap is formed between the solid immersion lens26and the optical storage medium18. The air gap is an interval within one wavelength of the light used. In the optical data storage system, a near-field generating portion is defined at a predetermined position on the surface of the solid immersion lens26which opposes the optical storage medium18. A beam spot is formed in the near-field generating portion.

In operation, the light transmission and reception portion20emits light beams having an optimized spread-width for the objective lens24, the reflective mirror22reflects the light beams toward the objective lens24, and the objective lens24focuses the light beams on the solid immersion lens26. In the case that the interval of the air gap is sufficiently smaller than one wavelength of the light beams, such as λ/4, the spot size of the light beams incident to the optical storage medium18is close to the size of the beam spot formed in the near-field generating portion. Therefore, the optical data storage system can write or read information with respect to the recording layer of the optical storage medium18, using the solid immersion lens26.

However, because the spot size of the light beams incident to the optical storage medium18is close to the size of the beam spot formed in the near-field generating portion, the size of the beam spot is too large to write or read information at higher density with respect to the optical storage medium18.

What is needed, therefore, is an optical data storage system which can write or read information at higher density with respect to the optical storage medium.

SUMMARY

In a preferred embodiment of the present invention, an optical data storage system includes a light emitting and receiving device, a light transmission device having an input port and an output port. The input port is disposed adjacent to the light emitting and receiving device. Furthermore, a micro window is provided at the output port, and a diameter of the micro window is in a range of 5 to 70 nanometers.

In a second embodiment of the present invention, an optical data storage system includes a light source, and a light transmission device having an input port and an output port. The input port is disposed adjacent to the light source. Furthermore, a micro window is provided at the output port, and a diameter of the micro window is in a range of 5 to 70 nanometers.

In a third embodiment of the present invention, an optical data storage system includes a detector, and a light transmission device that has an input port and an output port. The input port is disposed adjacent to the detector. Furthermore, a micro window is provided at the output port, and a diameter of the micro window is in a range of 5 to 70 nanometers.

In the optical data storage system, the spot size of the light beams is close to the diameter of the micro window. Accordingly, the size of the beam spot is small enough to write information at a higher density with respect to an optical storage medium.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIG. 1, an optical data storage system of a first embodiment of the present invention includes a light processing device with a light source30, a light transmission device like an optical fibre31, and a solid immersion lens36supported by a slider38. An optical storage medium39(only partly shown) is used together with the optical data storage system. Typically, the light source30may be part of an optical emitting and receiving device, i.e., the light processing device. The slider38aerodynamically floats the solid immersion lens36above the optical storage medium39. Instead of the optical fibre31, another kind of light transmission device of the art may be used. Instead of the solid immersion lens36, another kind of optical focusing device of the art may be used.

The optical fibre31has an upper portion32and a lower portion33. The upper portion32includes an input port (not labeled) disposed adjacent to the light source30. The lower portion33includes an output port (not labeled) disposed adjacent to the solid immersion lens36.

Referring toFIG. 2, this is an enlarged, side cut-away view of the lower portion33. The lower portion33is formed with the shape of a frustum of a cone by an FBT (Fused Biconical Taper) method or a chemical etching method. The lower portion33includes an exterior333and an interior330. A micro window331is defined at a bottom of the interior330, the micro window331being adjacent to the solid immersion lens36. A diameter of the micro window331is in a range of 5 to 70 nanometers. A reflector332is provided on an inner surface of the exterior333. Preferably, a material of the reflector is silver or aluminum.

Referring toFIG. 3, this an enlarged, schematic, side cross-sectional view of the optical storage medium39. The optical storage medium39includes a substrate393, a protective layer391, and a recording layer392between the substrate393and the protective layer391. The protective layer391has a thickness in a range of 100 to 200 nanometers. A material of the protective layer391is glass or resin. The recording layer392has a thickness in a range of 10 to 20 nanometers. A material of the recording layer392is GeTeSb.

In operation, light beams emitted by the light source30irradiate the input port and enter the optical fibre31. The incident light beams pass through the upper portion32and the lower portion33, and emit from the micro window331. The solid immersion lens36focuses the light beams emitted from the micro window331, and writes information with respect to the optical storage medium39. The reflector332on the inner surface of the exterior333can improve the utilization of light beams.

When the light beams have a wavelength in a range of 400 to 760 nanometers, the diameter of the micro window331should be controlled to be in a range of 10 to 70 nanometers. In such case, the light beams emitted from the micro window331generate a near-field between the lower portion33and the solid immersion lens36, and prevent diffraction. When the light beams have a wavelength in a range of 200 to 300 nanometers, the diameter of the micro window331should be controlled to be in a range of 5 to 30 nanometers, so as to generate the near-field.

In each case, the spot size of the light beams incident to the optical storage medium39is close to the diameter of the micro window331. Therefore the size of the beam spot is small enough to write information at a higher density with respect to the optical storage medium39.

When the optical storage medium39is used together with the optical data storage system, the recording layer392is irradiated by the light beams emitted from the solid immersion lens36, and a plurality of recording points having reflection functions are defined on the recording layer392. A size of each recording point is close to the diameter of the micro window331, therefore a recording density per inch of the recording layer392is about 100 Gigabits.

When reading information from the optical storage medium39, an optical detector is positioned adjacent to the upper portion32of the optical fibre31. Typically, the optical detector may be part of an optical emitting and receiving device or included in the above-mentioned light processing device. In this situation, the optical fibre31is used as an optical pick-up device. The micro window331functions as a nanometer probe, and receives reflective light beams from the recording point. The light beams pass through the lower portion33and the upper portion32and irradiate the optical detector. The optical detector receives the light beams, and transforms the light beams into electric signals. The electric signals are stored or output to a user in the form of information, a visual display, sound, etc.

When writing and/or reading information with respect to the optical storage medium39, a light source (such as the light source30) and an optical detector are used together as an optical emitting and receiving device.

In the optical data storage system, the spot size of the light beams incident to the optical storage medium is close to the diameter of the micro window. Thus, the size of the beam spot is small enough to write information at a higher density with respect to the optical storage medium.

The optical fibre having the micro window therein generates the near-field and prevents diffraction. Accordingly, the optical fibre can be used for optical processing involving nanometer dimensions. Using a light source having a predetermined wavelength and/or high power irradiation on an array of optical fibres, a predetermined pattern can be formed on the surface of a processing unit.