CN1332387C - Solid immersion lens for near field optical storage - Google Patents
Solid immersion lens for near field optical storage Download PDFInfo
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- CN1332387C CN1332387C CNB2005100493141A CN200510049314A CN1332387C CN 1332387 C CN1332387 C CN 1332387C CN B2005100493141 A CNB2005100493141 A CN B2005100493141A CN 200510049314 A CN200510049314 A CN 200510049314A CN 1332387 C CN1332387 C CN 1332387C
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- solid immersion
- immersion lens
- negative index
- near field
- media layer
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- 238000007654 immersion Methods 0.000 title claims abstract description 73
- 239000007787 solid Substances 0.000 title claims abstract description 73
- 230000003287 optical effect Effects 0.000 title claims description 17
- 230000035699 permeability Effects 0.000 claims description 4
- 230000013011 mating Effects 0.000 claims 1
- 230000004044 response Effects 0.000 abstract description 3
- 230000009347 mechanical transmission Effects 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 2
- 108091006149 Electron carriers Proteins 0.000 description 1
- 229910000618 GeSbTe Inorganic materials 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000009514 concussion Effects 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000004038 photonic crystal Substances 0.000 description 1
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Abstract
The present invention discloses a solid immersion lens for near-field light storage. A negative refraction medium layer which can focus laser at the lower surface of the solid immersion lens to the surface of a disc again is coated at the lower surface of the traditional solid immersion lens. When in use, the relative dielectric constant and the magnetic conductivity of the negative refraction medium layer and an air gap are matched at working wavelength, and the thickness of the air gap is the same as the thickness of the negative refraction medium layer. The present invention can greatly increase the distance between the lower surface of the solid immersion lens and the disc on the basis of no reducing signal response when reading data and resolution when reading /writing the data so as to lower the requirements for a servo system m a mechanical transmission system and a recording environment.
Description
Technical field
The present invention relates to optical storage technology and artificial electromagnetic medium field, especially, relate to a kind of solid immersion lens that is used for the near field of light storage.
Background technology
Optical storage technology has brought revolutionary impact to areas of information technology.Optical storage is information carrier with the photon, it can enter into electron carrier inaccessiable superelevation storage density, ultrafast memory rate and parallel I/O, highly interconnected field.At present, various CD drive read or write with the optical head that comprises object lens, and finish and focus on and the track servocontrol, because object lens are stored so be called the far field apart from medium (millimeter level) far away.The lifting of its storage density is subjected to the diffraction resolution limit the most at last, and (therefore the restriction of 0.5 λ/NA), is sought new optical storage principle in order to satisfy the ever-increasing market demand and is become particularly urgent.
The near field of light memory technology with its advantage that can break through the diffraction resolution limit, becomes an important development direction of present optical storage research.Wherein, solid immersion lens (Solid Immersion Lens:SIL) technology is a kind of structure and the better simply relatively mode of principle.As shown in Figure 1, by with a conventional solid immersion lens 6, be inserted into the below of the condenser lens 5 of optical disk head, and allow laser just in time converge on the lower surface of solid immersion lens, can improve the numerical aperture NA of optical head like this, reduce the size of hot spot.Dome-type SIL can make spot size be reduced to and insert preceding n
SIL(n doubly
SILBe the refractive index of solid immersion lens).But the NA of optical head that comprises SIL usually is greater than 1 (NA is less than 1 in the storage of far field), at this moment, laser will produce evanescent wave (evanescentwave) after seeing through the lower surface of solid immersion lens in air-gap 7, its amplitude is exponential damping along the direction of propagation.Therefore, play a role effectively for making solid immersion lens, the spacing between its lower surface and the video disc will remain within the distance of near field, and the thickness of air-gap 7 is tens nanometers usually.This has all proposed very high requirement for servo-drive system, machine driven system and record environment.
In addition, in recent years, be that the scientific research of the novel artificial electromagnetic medium (meta-materials) of representative has obtained concern more and more widely with the negative index media, become one of current very forward position and popular research field.The refractive index of this negative index media is a negative value, the characteristic that it has negative refraction (negative refraction) and evanescent wave amplifies (amplification of evanescent wave).Theoretical and experimentally all verified, a negative index media flat board can be opposite to object before it to carry out subwave and grows up to picture, and the resolution of its imaging will break through diffraction limit.Because the refractive index of natural medium is all for just, therefore, this negative index media can only be a synthetic.At present, microwave section and optical band all success produce this negative index media.But, also not the relevant report of this artificial electromagnetic media applications in the solid immersion lens of near field of light storage.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of novel solid immersion lens is provided, on the basis of signal response that it can be when not reducing reading of data and the resolution during the read/write data, improve the lower surface of solid immersion lens and the distance between the video disc significantly, thereby reduce servo-drive system, machine driven system and record environment requirement.
For realizing this goal of the invention, the technical solution used in the present invention is: a kind of solid immersion lens, form by solid immersion lens with at the negative index media layer that the lower surface of solid immersion lens applies; During use, the laser that the negative index media layer will focus on the solid immersion lens lower surface focuses on again; Described negative index media layer is that uniform dielectric or equivalent refractive index with negative index are negative artificial microstructure.
The present invention also aims to provide a kind of solid immersion lens near field of light storage system.
For realizing this goal of the invention, the technical solution used in the present invention is: a kind of solid immersion lens near field of light storage system, it is characterized in that, comprise laser diode, collimation lens, optical splitter, aperture, object lens, air-gap, video disc, detector, solid immersion lens and a negative index media layer that applies at the lower surface of solid immersion lens, described negative index media layer is that uniform dielectric or equivalent refractive index with negative index are negative artificial microstructure.In use, the relative dielectric constant and the magnetic permeability of this negative index media layer and air-gap mate under operation wavelength, and the Thickness Design of air-gap is identical with the thickness of negative index media layer.
Beneficial effect of the present invention is:
1. on the basis of the resolution when signal response that it can be when not reducing reading of data and read/write data, improve the lower surface of SIL and the distance between the video disc significantly.
2. near the spot diameter of laser focusing its focal plane is relative less with the light intensity variation, therefore, can increase the tolerance to air-gap thickness to a certain extent.
Because above characteristic, the solid immersion lens that this is novel can reduce servo-drive system, machine driven system and record environment requirement.
Description of drawings
Fig. 1 is a conventional solid immersion lens near field of light storage system sketch;
Fig. 2 is a solid immersion lens sectional view of the present invention;
Fig. 3 is a solid immersion lens near field of light storage system sketch of the present invention;
Fig. 4 (a) and (b) be respectively the near field of light field pattern of conventional solid immersion lens and solid immersion lens of the present invention under the situation of not considering video disc; Fig. 4 (c) is the field pattern of light field aerial picture plane and solid immersion lens lower surface of the present invention.
Fig. 5 (a) and (b) be respectively the detector signal of the near field of light storage system of conventional solid immersion lens and solid immersion lens of the present invention when information symbol spatial frequency is zero and the graph of relation of signal contrast and air-gap thickness.
Fig. 6 (a) and (b) are respectively the normalized signal contrast of the near field of light storage system of conventional solid immersion lens and solid immersion lens of the present invention when different air-gap thickness ha and the graph of a relation of information symbol spatial frequency.
Fig. 7 is the signal contrast of near field of light storage system when information symbol spatial frequency is zero and the air-gap thickness graph of a relation with respect to the variation of design load.
The explanation of parts in the accompanying drawing:
1. laser diode, 2. collimation lens, 3. optical splitter, 4. aperture, 5. object lens, 6. conventional solid immersion lens, 7. air-gap, 8. video disc, the 9. symbol of the information in the video disc, 10. detector, 11. solid immersion lens of the present invention, 11a. solid immersion lens, 11b. negative index media layer
Embodiment
Describe the present invention below with reference to the accompanying drawings in detail.
As shown in Figure 2, solid immersion lens 11 of the present invention is that lower surface at solid immersion lens 11a is coated with and is covered with a negative index media layer 11b.Negative index media layer 11b can be the uniform dielectric (homogeneous material) with negative index, also can be that equivalent refractive index is the artificial microstructure of bearing, as: photonic crystal.
Fig. 3 is a solid immersion lens near field of light storage system sketch of the present invention.Among the figure, solid immersion lens near field of light storage system is made up of laser diode 1, collimation lens 2, optical splitter 3, aperture 4, object lens 5, air-gap 7, video disc 8, detector 10 and solid immersion lens of the present invention 11.The conventional solid immersion lens 6 that solid immersion lens 11 replaces among Fig. 1.At this moment, negative index media layer 11b can focus on the laser that focuses on solid immersion lens 11a lower surface the surface of video disc 8 again.In use, the relative dielectric constant and the magnetic permeability of this negative index media layer 11b and air-gap 7 mate under operation wavelength, and the thickness h of air-gap
aBe designed to thickness h with the negative index media layer
LIdentical.At this moment solid immersion lens 11a lower surface focal beam spot can be close to the surface that perfectly images in video disc 8.
Among Fig. 4,5,6,7, compared the performance of conventional solid immersion lens and solid immersion lens near field of light storage system of the present invention with the method for two-dimensional time-domain finite-difference algorithm (2D-FDTD) and vector diffraction.Here, getting operation wavelength is 650nm, and the numerical aperture of object lens 5 is 0.6, video disc 8 is for being generally used for the phase change disc of near field of light storage, the refractive index of air-gap 7 is 1, and its information symbol 9 alternately is made up of polycrystalline attitude and amorphous state phase change medium (GeSbTe), has certain spatial frequency f
sThe relative dielectric constant of negative index media 11b in the design novel solid immersion lens 11 is ε
L=-1+j6 * 10
-4, relative permeability is μ
L=-1+j6 * 10
-4, the refractive index of solid immersion lens 11a is n
S=1.843.The refractive index of the conventional solid immersion lens 6 that compares with it is n
S=1.843.
As shown in Figure 4, Fig. 4 (a) and (b) in dotted line represent the interphase of different medium; Solid line among Fig. 4 (b) is represented airborne focal plane (that is, the distance from air/negative index media interface equals the plane of 700nm); Solid line among Fig. 4 (c) is illustrated in the optical field distribution that the interface of solid immersion lens and negative index media goes out, and dotted line is illustrated in the optical field distribution on the airborne focal plane.The novel solid immersion lens can make light field converge in air, and a focal beam spot forms in air.The position of this focal beam spot equals the thickness h of negative index media layer from the air/distance at negative index media interface
L(being 700nm in this example).It can regard the picture of the focal beam spot of solid immersion lens lower surface as, and this picture has the spot size of breaking through diffraction limit equally.
As shown in Figure 5, solid line is represented signal contrast V among Fig. 5, and dotted line is represented the maximal value I of detector signal
x, dotted line is represented the minimum value I of detector signal
aIn conventional solid immersion lens near field of light storage system, when the thickness of air-gap 7 increased, its signal contrast reduced rapidly.When the thickness of further increase air-gap 7 increases, be the concussion of an amplitude fading.And in novel solid immersion lens near field of light storage system, when the thickness h of air-gap
aThickness h with the negative index media layer
LWhen identical, detector signal and signal contrast remain unchanged substantially, are a constant.Usually signal contrast is big more, and the signal to noise ratio (S/N ratio) of read output signal is good more.Signal contrast is defined as V=|I
x-I
a|/| I
x+ I
a|.I wherein
xAnd I
aFor, contain the certain space frequency f reading
sThe video disc of information symbol the time, the minimum and maximum value of detector signal.
Fig. 6 is the graph of a relation of normalized signal contrast and information symbol spatial frequency.Solid line is represented h
a=50nm, thick dashed line is represented h
a=200nm, fine dotted line is represented h
a=400nm, dot-and-dash line is represented h
a=700nm, each bar curve can be regarded a low-pass filter as, and its bandwidth determines the recording density of video disc usually.In conventional solid immersion lens near field of light storage system, when the thickness of air-gap 7 increased, the bandwidth of curve reduced rapidly.And in novel solid immersion lens near field of light storage system, when the thickness h of air-gap
aThickness h with the negative index media layer
LWhen identical, the bandwidth of curve remains unchanged substantially.
Fig. 7 is the signal contrast of near field of light storage system and the air-gap thickness graph of a relation with respect to the variation of design load.Among the figure, solid line is represented solid immersion lens (h of the present invention
L=h
a=700nm), dotted line is represented conventional solid immersion lens (h
a=50nm).In solid immersion lens near field of light storage system of the present invention, the thickness h of air-gap
aTolerance can reach about 40nm, and in conventional solid immersion lens near field of light storage system, the thickness h of air-gap
aTolerance only be 15nm.The thickness h of air-gap
aTolerance be defined as the thickness h of one section air-gap
aVariation range, in this segment limit, the variation of signal contrast is no more than at h
aDuring for its design load 10%.
Claims (4)
1. a solid immersion lens is characterized in that, forms by solid immersion lens (11a) with at the negative index media layer (11b) that the lower surface of solid immersion lens (11a) applies; During use, the laser that negative index media layer (11b) will focus on solid immersion lens (11a) lower surface focuses on again; Described negative index media layer (11b) is that uniform dielectric or equivalent refractive index with negative index are negative artificial microstructure.
2. solid immersion lens near field of light storage system, it is characterized in that, comprise laser diode (1), collimation lens (2), optical splitter (3), aperture (4), object lens (5), air-gap (7), video disc (8), detector (10), solid immersion lens (11a) and a negative index media layer (11b) that applies at the lower surface of solid immersion lens (11a), described negative index media layer (11b) is that uniform dielectric or equivalent refractive index with negative index are negative artificial microstructure.
3. solid immersion lens near field of light storage system according to claim 2 is characterized in that, during use, and the relative dielectric constant and the magnetic permeability of described negative index media layer (11b) and air-gap (7) and under operation wavelength, mating.
4. solid immersion lens near field of light storage system according to claim 2 is characterized in that, during use, and the thickness h of described air-gap (7)
aThickness h with described negative index media layer (11b)
LIdentical.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100493141A CN1332387C (en) | 2005-03-09 | 2005-03-09 | Solid immersion lens for near field optical storage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100493141A CN1332387C (en) | 2005-03-09 | 2005-03-09 | Solid immersion lens for near field optical storage |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1684169A CN1684169A (en) | 2005-10-19 |
| CN1332387C true CN1332387C (en) | 2007-08-15 |
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ID=35263448
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100493141A Expired - Fee Related CN1332387C (en) | 2005-03-09 | 2005-03-09 | Solid immersion lens for near field optical storage |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102013203628B4 (en) * | 2013-03-04 | 2020-06-10 | Leica Microsystems Cms Gmbh | Immersion objective for microscopes and its use |
| KR102076021B1 (en) * | 2015-05-04 | 2020-03-02 | 에이에스엠엘 네델란즈 비.브이. | Method and apparatus for inspection and measurement |
| KR20210013695A (en) | 2018-05-22 | 2021-02-05 | 쓰리엠 이노베이티브 프로퍼티즈 컴파니 | Optical film with light control edge |
| CN110673353B (en) * | 2019-11-13 | 2021-07-30 | 南京大学 | Super-resolution focusing device based on high-refractive-index material |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6137632A (en) * | 1999-04-19 | 2000-10-24 | Iomega Corporation | Method and apparatus for lossless beam shaping to obtain high-contrast imaging in photon tunneling methods |
| US20030067860A1 (en) * | 2001-10-10 | 2003-04-10 | Industrial Technology Research Institute | Near-field optical flying head |
| WO2004053557A1 (en) * | 2002-12-10 | 2004-06-24 | Asahi Glass Company, Limited | Objective lens for optical information recording media |
-
2005
- 2005-03-09 CN CNB2005100493141A patent/CN1332387C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6137632A (en) * | 1999-04-19 | 2000-10-24 | Iomega Corporation | Method and apparatus for lossless beam shaping to obtain high-contrast imaging in photon tunneling methods |
| US20030067860A1 (en) * | 2001-10-10 | 2003-04-10 | Industrial Technology Research Institute | Near-field optical flying head |
| WO2004053557A1 (en) * | 2002-12-10 | 2004-06-24 | Asahi Glass Company, Limited | Objective lens for optical information recording media |
Non-Patent Citations (1)
| Title |
|---|
| 异向介质研究进展 冉立新，陈红胜，皇甫江涛，章献民，陈抗生，孔金瓴，微波学报，第20卷第3期 2004 * |
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| Publication number | Publication date |
|---|---|
| CN1684169A (en) | 2005-10-19 |
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Granted publication date: 20070815 Termination date: 20110309 |