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111.
In this paper, we demonstrate the monolithic integration of a conventional waveguide, a photonic crystal demultiplexer, a photonic crystal taper coupler, photonic crystal waveguides, and photodiodes in InGaAsP-based material to form a planar nano-optics system. Photonic crystal demultiplexers consist of hexagonally arranged air holes. Finite-difference time-domain method is implemented to investigate the performance of the demultiplexer. The system is fabricated using e-beam lithography and conventional photolithography. The input light at wavelengths of 1530 and 1550 nm can be separated using the demultiplexing system. These can then be detected by photodiodes that exhibit a wide-bandwidth performance of 22 GHz. 相似文献
112.
Simultaneous measurement of curvature and temperature based on PCF-based interferometer and fiber Bragg grating 总被引:2,自引:0,他引:2
Yan Zhou Wenjun Zhou Chi Chiu Chan Li-Yang Shao Xinyong Dong 《Optics Communications》2011,284(24):5669-5672
A sensor head consisting of a photonic crystal fiber (PCF)-based Mach-Zehnder interferometer (MZI) and a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of curvature and temperature. The MZI fabricated by splicing a short length of PCF between two single-mode fibers with the air-hole structure that completely collapsed near the splicing points, is sensitive to fiber bending and surrounding temperature, while the FBG is only sensitive to the later. Simultaneous measurement of curvature and temperature is therefore obtained. Sensitivities of 4.06 nm/m− 1 and 6.30 pm/°C are achieved experimentally for curvature and temperature, respectively. And the corresponding resolutions are 5.2 × 10− 4 m− 1 and 1.25 °C for curvature and temperature, respectively, based on the wavelength measurement resolution of 10 pm. 相似文献
113.
Biological specimens have to be prepared for imaging in the electron microscope in a way that preserves their native structure. Two-dimensional (2D) protein crystals to be analyzed by electron crystallography are best preserved by sugar embedding. One of the sugars often used to embed 2D crystals is trehalose, a disaccharide used by many organisms for protection against stress conditions. Sugars such as trehalose can also be added to negative staining solutions used to prepare proteins and macromolecular complexes for structural studies by single-particle electron microscopy (EM). In this review, we describe trehalose and its characteristics that make it so well suited for preparation of EM specimens and we review specimen preparation methods with a focus on the use of trehalose. 相似文献
114.
A highly sensitive miniature photonic crystal fiber refractive index sensor based on field mode excitation is presented. The sensor is fabricated by melting one end of a photonic crystal fiber into a rounded tip and splicing and collapsing the other end with a single-mode fiber. The rounded tip is able to induce cladding mode excitation, which resulted in an additional phase delay. Linear response of 262.28 nm/refractive index unit in the refractive index range of 1.337 to 1.395 is obtained for the physical length of a 953 μm sensor. The sensor is also shown to be insensitive to environmental temperature. 相似文献
115.
An optical phase modulator is presented by using micro-electro-mechanical systems to actuate deformable silicon waveguides. Via mechanically stretching the waveguide length, the optical path is extended, resulting in a phase shift. The experimental results show that a phase shift of near 0.4π is achieved at 200 V for both TE- and TM-polarized waves by cascading six phase modulation units, agreeing well with the theoretical prediction. The power consumption is estimated to be smaller than 0.2 mW at 200 V, mainly resulting from the leakage current. 相似文献
116.
When the polarization direction of the laser beam ê lies on the graphene plane, the absorption spectrum A(ω)is isotropic and includes one sharp peak and some shoulders. As for ê along the stacking direction, A(ω) is much weaker, and shows only one broadened peak. Because of the dipole matrix element M(cv), the optical excitations do not fully reflect the features of electronic structures [or the joint density of states (JDOS)]. M(cv) plays an important role in the relationship between A(ω) and JDOS. It is strongly dependent on ê, showing an anisotropic property. 相似文献
117.
Lee Ming-Kwei Yen Chih-Feng Chiu Shih-Chen 《Applied Physics A: Materials Science & Processing》2011,104(4):1175-1180
The electrical characteristics of thin TiO2 films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO2 film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10−2 and 1.1×10−4 A/cm2 at +2 V bias and 1.6×10−1 and 8.3×10−4 A/cm2 at −2 V bias. The lower leakage currents of TiO2 with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide
charge number density are 33 and 2.5×1013 cm2, respectively. The lowest mid-gap interface state density is around 7.6×1011 cm−2 eV−1. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range
of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm. 相似文献
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120.
Ming Ming Chiu 《Mathematical Thinking and Learning》2013,15(2-3):93-124
In this study, novices and experts used the same metaphors to understand and solve problems with negative numbers. However, they used them differently. Twenty-four participants (12 middle school children and 12 postsecondary adults) computed arithmetic expressions during the problem-solving task. During this task, children used metaphors more often than adults did to compute, detect and correct errors, and justify their answers. Metaphorical computations were more accurate but slower than other methods. The participants explained 6 arithmetic expressions during the understanding task. During this task, the adults used more metaphors (with fewer details) and used them more often than the children did. Compared to the median child, the median adult showed a more integrated understanding of arithmetic through multiple metaphors, mathematical rules, and transformations. These results suggest that the metaphors used by both the children and the adults are central to understanding arithmetic. Thus, these metaphors are likely candidates for theory-constitutive metaphors. 相似文献