Pit Depth and Width Modulation Multilevel Run-Length Limited Read-Only Optical Storage

When the techniques of integrating the variation of the conventional DVD,the high-density multilevel run-length pit depth and width simultaneously are adopted to limited read-only optical storage method is achieved. The dynamic range of readout signal is greatly enlarged in comparison with keeping one parameter varied, and the recording levels number can be obviously increased. The discs can be manufactured using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs. Experimental results show that eight-level read-only optical disc can be realized and the capacity can be increased to 20 GB.     

一种新的多阶只读光存储方法的仿真分析和实验验证

提出了一种波形调制的方法,在原有记录符中加入一个短坑或短岸,在读出信号上产生一个可辨识的"扰动",从而对读出信号波形产生调制.用简化的光刻模型和基于角谱分解的读出模型,对该方法在DVD系统上的坑形和读出信号进行了仿真.仿真结果确定了各个游程可实现的阶次和各个阶次的刻写参量.对典型游程6T和11T进行了实验,读出信号与仿真结果相吻合,并分别得到了小于1×104和1×10-5的阶次误码率.实验结果验证了该方案的实际可行性.     

Approximated Vector Diffraction Theory for Readout Signal of Multi-Level Run-Length-Limited Discs

Multi-level run-length-limited read-only optical storage is a kind of high density storage method. The width and height of recording marks are varied with different levels, which is the key technology for the optical storage. Then the readout signal of these discs with complex recording marks is computed by vector analysis method, it is very hard and time-consuming. Approximated vector computation combines the convenience of scalar method and precision of vector method, which is effective for multi-level run-length-limited read-only optical storage.     

Si掺杂Ag基超分辨薄膜读出性能研究

超分辨薄膜是一种能够实现突破光学衍射极限的功能薄膜,它在超分辨近场光存储技术中起到至关重要的作用。采用磁控溅射共溅的方式制备了Ag掺杂一定量Si的超分辨复合薄膜,测试了其作为掩膜层的超分辨光盘读出性能,并获得了最佳的薄膜制备条件,即当Ag溅射功率为55 W,Si为95 W,溅射时间为80s,薄膜厚度为39nm时,超分辨光盘的读出信号载噪比(CNR)最高为28dB。用X射线光电子能谱测量了上述薄膜的组成,用扫描电子显微镜观察了薄膜微区形貌,并用椭圆偏振光谱仪测量了薄膜的光学常数和厚度。超分辨复合薄膜的读出机理可以用Ag的散射型机理解释。光盘在持续读出10万次以后读出信号基本没有下降。     

Super-resolution readout property of bismuth-doped antimony-based thin film as a functional mask for read-only memory

Bismuth-doped antimony-based (Sb_100?x Bi _x , x=2.46) thin films were presented as a functional mask for super-resolution readout of read-only memory (ROM). The pit size of the ROM was 390?nm, and super-resolution readout was realized on a dynamic tester with laser wavelength of 780?nm and the numerical aperture of the focusing objective lens of 0.45. The carrier-to-noise ratio (CNR) of 22?dB, readout threshold power of 0.8?mW and super-resolution readout cycles of 2×10⁴ was achieved. The influence of film thickness and readout power on CNR was investigated. The reflectivity and transmittance of the film with different temperature at wavelength of 780?nm were detected, and the super-resolution mechanism of the bismuth-doped antimony-based thin films as the functional mask layer was discussed.     

Low-Power Super-resolution Readout with Antimony Bismuth Alloy Film as Mask layer

Sb-Bi alloy flms are proposed as a new kind of super-resolution mask layer with low readout threshold power. Using the Sb-Bi alloy film as a mask layer and SiN as a protective layer in a read-only memory disc, the superresolution pits with diameters of 380 nm are read out by a dynamic setup, the laser wavelength is 780 nm and the numerical aperture of pickup lens is 0.45. The effects of the Sb-Bi thin film thickness, laser readout power and disc rotating velocity on the readout signal are investigated. The results show that the threshold laser power of super-resolution readout of the Sb-Bi mask layer is about 0.5 m W, and the corresponding carrier-to-noise ratio is about 20 dB at the film thickness of 50nm. The super-resolution mechanism of the Sb-Bi alloy mask layer is discussed based on its temperature dependence of reflection.     

Holographic read-only memory

We describe the three-dimensional holographic optical disc system for application as read-only memory. Several systems design issues are discussed including imaging optics, storage density, readout rate, and the alignment servo system. We demonstrate 40 bits/m² surface density and pixel-matched holographic data readout from a 12 cm disc spinning at 600 RPM.     

Multilevel read-only optical recording methods

The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel (ML) read-only technology has been a trend to improve the data capacity and transfer rate. Based on the principle and coding method of ML, this paper demonstrates some ML read-only recording methods, of which a new ML read-only recording is developed. This recording method integrates amplitude modulation achieved by the reaction mechanism of physics and chemistry of photoresist with the run-length-limited technology. The discs can be achieved using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs.     

A Prototype of X-Ray Imaging Based on the GEM Detector

A prototype of X-ray imaging device based on triple Gas Electron Multiply detector is studied,which has an effective gain up to 10⁵ and can be used in high rate X-rays imaging.The precise method of micro–strip readout is designed for X-rays localization, and the crate controller of high–speed SCSI interface is applied for the data acquisition.The test results show that the position resolution of measurement system is less than 90μm and the stability of its effective gain is better than 1% under the X-ray flux of 10⁵Hz/mm².     

染料聚合物工艺母盘刻录坑形对读出信号调制幅度的影响分析

与光刻胶工艺相比,染料聚合物工艺母盘刻录的光盘坑形有很大区别。在已知文献中对坑点形貌与读出信号关系的研究结果已不再有效。使用基于角谱分解的衍射理论,利用原子力显微镜得到的坑形,对两种工艺光盘的调制幅度参数进行了仿真。仿真结果表明,对染料聚合物工艺而言,在较小的深度和宽度下能获得与光刻胶工艺光盘相当的调制幅度。对实际光盘几何尺寸和电信号参数的测试结果证明了仿真结果的正确性。     

Effect of Spectroscopy Amplifier Parameter on Identification of Light Charged Particles by Pulse Shaping Analysis Method

The pulse shaping analysis method is applied to identify the light charged particles emitted from ¹²C(46.7/MeV/u)+⁵⁸Ni reaction by using the CsI(T1) scintillator detector with photodiode readout.In the experiment,it is found that the particle identification greatly depends on the choice of spectroscopy amplifier shaping time constant.The problem is investigated on the basis of Laplace transformation method.The experimental phenomena have been successfully explanined.     

Ionizing Dose Effect of Thermal Oxides Implanted with Si^＋ Ions

Total ionizing dose effects of Si^＋ ion implanted thermal oxides are studied by 10keV x-ray irradiation. Photoluminescence （PL） method is engaged to investigate nanostructures of samples. Ar^＋ implanted samples are also studied by the same way to provide a comparison. The results show that Si^＋ implantation following with high temperature annealing can significantly reduce the radiation induced flatband shift, which is caused by net posi- tive charge accumulation in oxides. This reduction is attributed to the formation of Si nanoscale structures. Ar^＋ implantation is also found to reduce the radiation induced flatband shift, while it is different that the reduction with Si^＋ implantation shows little dependence on implant dose of Ar^＋ ions. This is explained by possible increase of recombination centres.     

Polarization readout analysis for multilevel phase change recording by crystallization degree modulation

Four different states of Si15Sb85 and Ge2Sb2Te5 phase change memory thin films are obtained by crystallization degree modulation through laser initialization at different powers or annealing at different temperatures. The polarization characteristics of these two four-level phase change recording media are analyzed systematically. A simple and effective readout scheme is then proposed, and the readout signal is numerically simulated. The results show that a high-contrast polarization readout can be obtained in an extensive wavelength range for the four-level phase change recording media using common phase change materials. This study will help in-depth understanding of the physical mechanisms and provide technical approaches to multilevel phase change recording.     

Analysis of differential phase detection signal of a novel multi-level read-only disc

To improve the tracking servo performance, a novel signal waveform multi-level （SWML） read-only disc realized on the digital versatile disc （DVD） platform is presented. The characteristic of the differential phase detection （DPD） signal of the SWML read-only disc is analyzed both in theory and experiment. The amplitude of the DPD signal of the SWML read-only disc in an open tracking servo loop is about 2/3 of that of the DVD read-only disc. The uniformity and symmetry of the DPD signal of the SWML read-only disc are similar to those of the DVD read-only disc and better than the former multi-level run-length limited （ML-RLL） read-onlv disc.     

Nonlinear signal-processing model for signal generation in multilevel two-dimensional optical storage

A two-dimensional optical storage (TwoDOS) format with binary modulation is being developed in which channel bits are arranged on a two-dimensional hexagonal lattice [W. M. J. Coene, in Optical Data Storage, Vol. 88 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 2003), pp. 90-92]. The aim is to increase the capacity by a factor of 2 and the data rate by a factor of 10 over third-generation Blu-ray Disc technology. Following a route similar to that used in one-dimensional conventional optical storage [Jpn. J. Appl. Phys. 42, 1074 (2003)] could lead to a further increase in capacity by the addition of another dimension to writing data, such as the use of multiple levels instead of the two levels (pit and land) used in the binary TwoDOS disk format. We present a nonlinear signal-processing model for signal waveform generation as a function of the M-ary channel symbols, as well as simulated signal readouts for multilevel TwoDOS.     

光盘信息符特征宽度的确定

光盘信息符的横向尺寸决定了光存储系统的存储面密度。采用二维正方形光栅作为光盘模型,通过三维矢量衍射理论的数值仿真,计算了信息符横向尺寸对读出信号调制度的影响,确定了最佳调制度对应的最佳坑宽。并与标量衍射理论的定性分析进行了对比。根据标量衍射理论,最佳调制度应出现在信息符面积为读出光斑面积一半时对应的信息符尺寸附近,且小于该尺寸;信息符的最佳坑宽,即信息符特征宽度取决于所用的光学系统;矢量衍射理论的定量计算结果符合标量衍射理论的分析,并更接近实际情况;标量衍射理论概念简单,适于定性分析,定量计算则存在较大的误差。     

真空净化处理对掺杂烧结型金刚石聚晶耐磨性的影响

 本文对金刚石原料和不同结合剂进行了真空净化处理试验研究。金刚石原料粒度越细，d电子亏损越多的过渡元素做结合剂，通常越需真空净化处理，方能烧结成高耐磨性聚晶金刚石。     

High Speed Signal Wavelength Conversion Using Stimulated Raman Effect in Ultrasmall Silicon-on-Insulator Optical Waveguides

We propose the high speed signal wavelength conversion based on stimulated Raman effect on silicon waveguides. Simulation results of non-return-to-zero （NRZ） pseudorandom bit sequence （2^7-1 code） at 500-Gb/s rate of conversion in an ultrasmall silicon-on-insulator （SOI） optical waveguide are presented by co-propagating pump optical field. The most attractive issue is that the inverted converted signal can be obtained at the same wavelength as that of primary signal. In addition, the conversion performances, including extinction ratio （ER） and average peak power of conversion signal, depend strongly on the launching pump intensity.     

A Group-Period Phase Comparison Method Based on Equivalent Phase Comparison Frequency

Based on the principle of equivalent phase comparison frequency, we propose a group-period phase comparison method. This method can be used to reveal the inherent relations between periodic signals and the change laws of the phase difference. If these laws are applied in the processing of the mutual relations between frequency signals, phase comparison can be accomplished without frequency normalization. Experimental results show that the method can enhance the measurement resolution to 10-13/s in the time domain.     

Correction to: Generation of amplitude- and phase-modulated signal beam with a phase-only spatial light modulator and its detection by the transport of intensity equation method for holographic data storage

This study evaluates a novel holographic data storage (HDS) that uses a phase-only spatial light modulator (SLM) for the multilevel complex amplitude modulation of a signal beam and the transport of intensity equation (TIE) method to detect the signal beam without interferometry, to increase the capacity of the HDS, simplifying its optical system, and improving the stability of the signal beam modulation and detection. Both the amplitude and phase of the signal beam were modulated by a computer-generated hologram displayed in a phase-only SLM, a 4-f optical system, and a pinhole placed in the Fourier plane. The complex amplitude-modulated signal beam generated by this scheme does not always perfectly match the target complex amplitude, and deviations from the amplitude and phase of the target complex amplitude may exist. It is unclear whether the TIE method, which is sensitive to the state of the beam intensity and the phase distributions to be detected (such as zero-intensity points and phase discontinuities), can accurately detect a signal beam whose complex amplitude is modulated by the modulation scheme with a phase-only SLM. Here, we demonstrate via numerical simulations and experiments that several methods of complex amplitude generation using a phase-only SLM can achieve multilevel modulation of the amplitude and phase of a signal beam and are suitable for detection by the TIE method in HDS.