Super Resolution Near Field Research Articles

Massively parallel direct writing of nanoapertures using multi-optical probes and super-resolution near-fields

Laser direct-writing enables micro and nanoscale patterning, and is thus widely used for cutting-edge research and industrial applications. Various nanolithography methods, such as near-field, plasmonic, and scanning-probe lithography, are gaining increasing attention because they enable fabrication of high-resolution nanopatterns that are much smaller than the wavelength of light. However, conventional methods are limited by low throughput and scalability, and tend to use electron beams or focused-ion beams to create nanostructures. In this study, we developed a procedure for massively parallel direct writing of nanoapertures using a multi-optical probe system and super-resolution near-fields. A glass micro-Fresnel zone plate array, which is an ultra-precision far-field optical system, was designed and fabricated as the multi-optical probe system. As a chalcogenide phase-change material (PCM), multiple layers of Sb65Se35 were used to generate the super-resolution near-field effect. A nanoaperture was fabricated through direct laser writing on a large-area (200 × 200 mm2) multi-layered PCM. A photoresist nanopattern was fabricated on an 8-inch wafer via near-field nanolithography using the developed nanoaperture and an i-line commercial exposure system. Unlike other methods, this technique allows high-throughput large-area nanolithography and overcomes the gap-control issue between the probe array and the patterning surface.

Proposed Superresolution Near-Field Photolithography Method

Proposed Superresolution Near-Field Photolithography Method

超分辨近场结构光盘的传统以及差分读出方法研究

超分辨近场结构光盘的传统以及差分读出方法研究

Turbo Equalization of Run Length Limited (1,9) and Low Density Parity Check Code for Super Resolution Nearfield Structure Read Only Memory Discs with 60 nm Minimum Mark Length

Due to severe intersymbol interference and low signal-to-noise ratio of super resolution nearfield structure (SuperRENS) random read-outs, turbo equalization techniques are applied to lower bit error rates. A d1k9r5 run length limited (RLL) modulation code having minimum runlength d = 1, maximum runlength k = 9 and repeated minimum transition run limitation of r = 5 has been developed with emphasis on low joint bit detection and demodulation (super-trellis) complexity for use within turbo equalization schemes. Bit error rate (BER) performance of d1k9r5 code over partial response-channels is similar to 17pp code while the super-trellis detector complexity of d1k9r5 code is reduced. Low-frequency suppression performance of d1k9r5 code is similar to that of 17pp code under the same DC control redundancy. BER results for measured data from a 60 nm SuperRENS read only memory disc employing an InSb mask layer, using d1k9r5 modulation and a high-rate quasi-cyclic low density parity check (LDPC) code, correspond well to simulation results. Continuously decreasing BERs down to 2 ×10-5 after five iterations show that a turbo equalization scheme incorporating d1k9r5 super-trellis detection can be successfully applied in SuperRENS storage systems together with an LDPC code.

Numerical Analysis and Comparison of Three Metal-Oxide-TypeSuper-Resolution Near Field Structures

Based on the Fresnel–Kirchhoff diffraction theory, webuild up a Gaussian diffraction model of metal-oxide-type super-resolution nearfield structure (super-RENS), which can describe far field optical properties. Thespectral contrast induced by refractive index and the structural changes inAgOx, PtOx and PdOx thin films, which are the key functional layersin super-RENS, are studied by using this model. Comparison results indicate that thespectral contrast depends intensively on the laser-induced distribution and changeof the refractive index in the metal-oxide films. The readout mechanism of themetal-oxide-type super-RENS optical disc is further clarified. This Gaussiandiffraction model can be used as a simple and effective method for choosing properactive materials in super-RENS.

Enhanced Readout Signal of Elliptic-Bubble Super Resolution Near Field Structure by Temperature-Dependent Complex Refractive Index of Phase-Change Medium

We propose a model elucidating the readout mechanism of the super resolution near-field structure (super-RENS) with an elliptic-bubble structure. The temperature dependence of the complex refractive index of Ge2Sb2Te5 is determined by in situ ellipsometry. The complex refractive index of Ge2Sb2Te5 shows quite an abrupt change at approximately 608°C. The temperature profile is calculated using a proposed first-order differential equation. Above the threshold readout power, Ge2Sb2Te5 is locally heated over the critical temperature when thickest region of Ge2Sb2Te5 is in commensurate with the center position of the Gaussian laser power distribution, which results in the abrupt amplification of signal-to-noise ratio (SNR) of the calculated reflectance. Thus, a model revealing the essential aspect of the elliptic-bubble super-RENS is proposed to elucidate its readout mechanism.

Bit Error Rate Characteristics of Write Once Read Many Super-Resolution Near Field Structure Disk

We firstly report the bit error rate (bER) characteristics of a super-resolution near-field structure (super-RENS) write-once read-many (WORM) disk in a blue laser optical system, (laser wavelength 405 nm, numerical aperture 0.85) with a carrier-to-noise ratio (CNR) at the 75 nm mark (50 GB Capacity) of 47 dB and a low frequency noise of approximately 20 dB. The recording state should be precisely controlled by an adequate writing strategy for bER measurement. Together with the above conditions, using the frequency-dependent gain controlled equalization (EQ) and advanced partial-response maximum likelihood (PRML) technique, bER of 10-3 order at 50 GB was obtained.

The Characteristics of Reactively Sputtered AgOx Films Prepared at Different Oxygen Flow Ratios and Its Effect on Super-Resolution Near-Field Properties

The characteristics of several reactively sputtered AgOx films, prepared at different oxygen flow ratios, with and without ZnS-SiO2 protective layers have been examined. For the as-deposited AgOx films, the amount and size of Ag clusters decreased, and the constituent phase of AgOx gradually transferred from pure Ag2O, to a mixture of Ag2O and AgO, then to pure AgO, as the oxygen flow ratio was increased. After annealing, the reduction of AgO into Ag2O and decomposition of Ag2O into Ag and O2 took place, and the decomposed Ag elements would diffuse outward and precipitate small silver particles on the surface of ZnS–SiO2 protective layers. The chemical decomposition of AgOx film confined by ZnS–SiO2 protective layers was confirmed to be an irreversible process. The super-resolution near field effect becomes significant only when the super-resolution near-field structure (super-RENS) disk with an AgOx mask layer prepared at oxygen flow ratios above a threshold value, where AgOx film consists of Ag2O or AgO phase.

Investigation on the mechanism of AgO x film super resolution near-field structure

Summary As a promising disk structure for ultrahigh density optical storage, super-resolution near field structure of AgO x type has been studied by both scanning tunneling microscopy and X-ray diffraction experiments. Irregular surface roughness is observed in super-resolution near field structure. And the decomposition of AgO x layer at 160 °C is confirmed. Both results of experiments demonstrate that super-resolution near field structure of AgO x type can satisfy the conditions of exciting surface plasmons.

Spectroscopic Investigation of AgOx Films for Super Resolution Near Field Structure Application.

In this work thin silver oxide layers (AgOx) were prepared by reactive sputtering of a silver target in oxygen containing atmosphere. We report a gradual composition change of the deposited layers with increasing oxygen concentration from Ag over Ag2O to AgO and furthermore that dispersed silver clusters are present even up to high O2 concentrations. Raman- along with IR-spectroscopy and ellipsometric measurements reveal specified compounds at defined oxygen concentrations. Optical transmission and reflection measurements as a function of temperature show that these compounds exhibit phase transitions (i.e. AgO decomposes to Ag2O and finally to Ag), connected to considerable refractive index changes. This work was done with respect to super-Resolution Near-Field Structures where these effects are exploited to realize ultra high optical data storage in combination with magneto-optical and phase change recording materials.

Investigations of Sputtered Silver Oxide Deposits for the SUPER–RENS High Density Optical Data Storage Application

ABSTRACTThin silver oxide films used as mask layers in super-Resolution Nearfield Structure (super-RENS) disks for high density optical data storage were reactively sputter-deposited and their composition was determined by spectroscopic means. We found that the stoichiometry of the films changed with the oxygen content in the sputtering gas atmosphere. With a stepwise increase in the percentage of O2 from 0 - 100%, the corresponding layers consist of Ag, mixtures of Ag and Ag2O, Ag2O, mixtures of Ag2O and AgO and AgO. Laser activation of such oxidic phase containing deposits results in the decomposition of the material and excitation of strong local plasmons in the remaining silver clusters. This was confirmed by acquiring surface enhanced Raman spectra (SERS) of benzoic acid (BA), copper phthalocyanine (CP) and internal carbon impurities on silver oxide substrates. From this data, we conclude that the sub-wavelength resolution obtained in super-RENS disks is mediated by local surface plasmons on small silver particles forming in the mask layer.