Multiple reflection effect inside a hemispherical solid immersion lens

The reflection inside a hemispherical solid immersion lens (h-SIL) is analyzed by using the film-interference optics and the new unique characteristic of the h-SIL is presented. The image theory of SIL microscopy is developed. Numerical results show that the reflection inside the h-SIL, especially for large mismatch in refractive indices between the SIL and the medium, has an important influence on the resolution of SIL surface microscope and the collection efficiency from the emitter. Theoretical and experimental results are compared through three examples, the reflection-mode microscope, the transmission-mode microscope, and the collection of light from the emitters. The present theoretical values are quite consistent with the experimental values in SIL microscopy. It is of interest to note that owing to the interference in the SIL, the resolution and collection efficiency periodically oscillate with the radius of an h-SIL, which mean that the radius of an h-SIL has to be well-controlled to achieve enough high resolution and collection efficiency.     

Fabrication of micrometer-size glass solid immersion lens

A micrometer-size solid immersion lens (μ-SIL) of glass with a super-spherical shape is obtained using a simple preparation procedure. Soda-lime–silica glass particles are melted on a glassy-carbon substrate with a surface of optical grade and cooled to room temperature. The obtained glass particles are transparent and have a super-spherical shape. Their shapes are found to satisfy the conditions of the SIL function for evanescent-field optics. Fine uneven surface textures of an integrated circuit with the depth of about 20 nm are clearly recognized using the prepared μ-SIL, and 1.8 times higher horizontal resolution than without the μ-SILis also attained. It was ensured that the glass μ-SILworks as the evanescent-field optics to visualize the nanometer-scale structure. PACS 42.70.Ce; 42.79.Bh; 68.03.Cd; 68.08.Bc; 68.37.Uv     

Numerical analysis of an annular-aperture solid immersion lens

A physical model of an annular-aperture solid immersion lens (SIL) is proposed, and its attractive features are presented numerically with the finite-difference time-domain method. Placing an appropriate annular aperture in front of the SIL shows that the focal depth can evidently be improved, combining the virtues of the annular-aperture technique and the SIL technique. With this proposed method the rigorous distance control condition in related devices can be relaxed, preventing scratches or collisions between the optical head and the recording medium. Potentially, this technique could have great prospects for applications in optical data recording, lithography, and other applications that depend on immersion media to meet the resolution criteria across the image field.     

Dispersion effect in optical microscopy systems with a supersphere solid immersion lens

This paper studies the dispersion effect of the supersphere solid immersion lens (SIL) on a near field optical microscopy system by using the vector diffraction theory. Results show that when a real non-monochromatic beam illuminates a supersphere SIL microscopy, the dispersion effect of the SIL has an important influence on the image quality. As the wavelength bandwidth of the non-monochromatic beam increases, the size of the focused spot increases and its intensity decreases in near-field microscopy systems with a supersphere SIL.     

Evanescent imaging with induced polarization by using a solid immersion lens

Image contrast enhancement, high lateral resolution, and height information are obtained with induced polarization evanescent imaging using a solid immersion lens. Experiments are conducted by imaging features on a patterned Si substrate. Imaging theory is used to predict optimum orientation of high-spatial-frequency samples, and a topographical image is derived from the induced polarization image through a calibration procedure. A numerical aperture of 1.5 is used in the experiment. Height accuracy of +/-2 nm is demonstrated with a known sample.     

固体浸没透镜光存储的信号探测技术

信号探测是固体浸没透镜成为实用存储技术的一个必需的组成部分。对在该项研究中获得的理论和实验成果进行了介绍。总结了针对固体浸没透镜机理的三维矢量理论 ,对影响信号探测的因素 ,例如头盘间距、盘片结构和光的偏振态等进行了讨论。介绍了基于固体浸没透镜光存储中信号探测的新技术和重要的实验结果。     

Improving the resolution of a solid immersion lens optical system using a multiphase Fresnel zone plate

We propose a method to improve the resolution of near-field optical system with a solid immersion lens by using a multiphase level Fresnel zone plate. The analyses are based on scalar angular spectrum theory. The results show that the multiphase Fresnel zone plate can not only decrease the spot size but also decrease the sidelobe intensity and enhance greatly the diffractive efficiency compared with annular amplitude filter or binary 2-, 3-, 4-zone phase filter.     

Optimizing the optical field distribution of solid immersion lens system by a continuous phase filter

In solid immersion lens (SIL) microscopy systems with high numerical aperture (NA), there always exists the aberration produced by Fresnel effects at the interface between SIL and the sample. This aberration may cause the degradation of the image of sample. We design a continuous phase filter and optimize the optical field distribution of SIL system. The numerical results show that when the continuous phase filter is used, the field distribution of SIL system can be optimized, and the focal depth and intensity of transmitted light can be increased. At the same time, the intensity of side-lobe and the resolution are kept almost unchanged.     

利用多扇区介质透镜得到TM01模激励的圆锥喇叭笔形波束辐射

 给出了一种改善TM₀₁模辐射特性的方法,由不同厚度的扇区组成的介质透镜放置于圆锥喇叭口径处,适当地选择各个扇区的厚度,从而产生圆极化的轴向为极大值的远场方向图。推导出了该天线辐射场的解析公式,解析结果与数值模拟有较好的吻合。当工作频率为5 GHz时,天线的增益达19.6 dB,口径效率31.3%,具有15.8%的带宽(反射系数S11<0.2), 且适合于高功率辐射。     

The validity of high-pass angular spectrum filter in solid immersion lens system

应用矢量方法计算了具有高通角谱滤波器的固体浸没透镜（SIL）系统的焦场分布。数值结果显示，对于径向（角向）偏振输入光，高通角谱滤波器可以减小SIL系统的光斑（暗斑）大小。然而，对于线性偏振输入光，简单的高通角谱滤波器不能够优化SIL系统的光场分布，也不能够改进系统的光存储密度。     

Three-zone phase-only filter increasing the focal depth of optical storage systems with a solid immersion lens

The field distribution of a Weierstrass solid immersion lens (SIL) is presented, which shows that its focal depth is only in nanoscale. A novel filter design based on a three-zone binary phase pupil function is introduced for increasing the focal depth of a near-field Weierstrass SIL system and a procedure for designing a rotationally symmetric binary phase filter is presented. Numerical results show that an appropriate three-zone phase-only filter not only can evidently increase the focal depth of the SIL system, but also can effectively lower the spreading of the spot size with distance and suppress the side-lobe intensity. PACS 42.79.Ci; 42.40.Lx; 42.79.Vb; 42.25.-p     

Three-dimensional optical data storage using a solid immersion lens to focus a femtosecond laser pulse

A solid immersion lens (SIL) has been applied to the writing and reading of three-dimensional optical datastorage in transparent materials. Using a SIL with n=1.516 to focus a 150-fs, 800-nm Ti:sapphire laser,the 5-layer reading and writing of data are achieved in fused silica and polyethylene methacrylate at adensity of 1.1× 1012b/cm3. Some advantages of the employment of SIL have been discussed.     

利用多扇区介质透镜得到TM01模激励的圆锥喇叭笔形波束辐射

给出了一种改善TM01模辐射特性的方法,由不同厚度的扇区组成的介质透镜放置于圆锥喇叭口径处,适当地选择各个扇区的厚度,从而产生圆极化的轴向为极大值的远场方向图。推导出了该天线辐射场的解析公式,解析结果与数值模拟有较好的吻合。当工作频率为5 GHz时,天线的增益达19.6 dB,口径效率31.3%,具有15.8%的带宽(反射系数S11<0.2), 且适合于高功率辐射。     

固体浸没透镜用于飞秒三维光存储研究

为进一步提高光存储密度，利用固体侵没透镜（SIL）与数值孔径为0.55的长工作距离物镜对飞秒激光脉冲进行聚焦，完成了PMMA及石英介质上的存储实验,并对聚焦物镜焦点与SIL底面离焦时的介质内焦点位置和系统的数值孔径进行了模拟。实验结果表明：当聚焦物镜焦点与SIL底面适当离焦时，实际聚焦在介质内的焦点深度不断加深，且系统的有效数值孔径不断增大。利用这一结果，在距PMMA表面20μm的地方得到了点间距1μm，层间距2.5μm的6层空间点阵；在距石英介质表面15μm的地方获得了点间距为0.6μm，层间距为2.5μm的5层空间点阵，其存储密度可达1.1×1012bits/cm3。     

Pupil-plane filtering for improved signal detection in an optical data-storage system incorporating a solid immersion lens

A pupil-plane filtering technique is applied to data-signal detection in an optical data-storage system that uses a solid immersion lens (SIL) and a four-layered phase-change recording medium. We have confirmed by numerical calculations and experiment that the technique improves signal contrast and makes the contrast less sensitive to the gap width between the bottom surface of the SIL and the top surface of the recording medium. Light that is incident upon the objective lens that is used with the SIL is linearly polarized, and the full vectorial feature of the light is considered in the calculations.     

压电晶体-液体-固体声波导中叉指换能器对导波的激发研究

本文对压电晶体－液体－各向同性固体结构的声波导中叉指换能器所激发的导波进行了理论研究和数值分析,给出了导波的相速度、叉指换能器激发导波的机电耦合系数与液体层归一化厚度、晶体取向之间的关系曲线,同时,还探讨了声波导中的位移场和电势场分布。     

Room temperature direct-bandgap electroluminescence from a horizontal Ge ridge waveguide on Si

We report a lateral Ge-on-Si ridge waveguide light emitting diode(LED) grown by ultrahigh vacuum chemical vapor deposition(UHV-CVD). Direct-bandgap electroluminescence(EL) of Ge waveguide under continuous current is observed at room temperature. The heat-enhancing luminescence and thermal radiation-induced superlinear increase of edge output optical power are found. The spontaneous emission and thermal radiation based on the generalized Planck radiation law are calculated and fit very well to the experimental results. The Ge waveguides with different lengths are studied and the shorter one shows stronger EL intensity.     

Waveguide tapering for beam-width control in a waveguide transducer

In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow beam width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow beam width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.     

Theoretical study of optical recording with a solid immersion lens illuminated by focused double-ring-shaped radially-polarized beam

Based on the Richards–Wolf vector diffraction theory, the intensity distributions in the recording sample near a solid immersion lens are calculated for two different radially-polarized beams ( and modes). Numerical results show that a double-ring-shaped mode focusing has some excellent features in near-field optical storage, compared with a single-ring-shaped mode focusing. The recording density is markedly improved, the focal depth of the near-field recording system is substantially increased, and a subsurface recording is effectively obtained using the mode focusing.