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There is now great interest in optical memory using a three-level atom embedded in photonic crystals, which can be used for quantum computing; however, quantum-information detection from the optical memory has not been demonstrated. In this paper, first, considering the relative position of the photonic band gap (PBG) and two atomic levels split from the upper level of the atom used for the optical memory, we demonstrate that one of the split levels must be outside the PBG for quantum-information detection. In this case, the quantum state of the atom can be changed by moving the other split level, where the quantum information is maintained or emitted for the cases in which the split level is inside or outside the PBG, respectively. The emitted quantum information can be measured as spontaneous emissions by a photon detector. Next, we propose two methods of moving the split level: one is realized by applying a direct current (DC) field to the atom and the other is realized by changing the intensity of the control laser field. Furthermore, by evaluating the intensities of the DC and the control laser fields, we find that the quantum information can be measured using the fields on the millielectronvolt order. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(8): 10–19, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10205 [ABSTRACT FROM AUTHOR]

In order to reduce the phase error in the FDTD analysis, Cole proposed the NS-FDTD method. However, in the paper by Cole, numerical dispersion characteristics and accurate stability condition were not presented. Also, definition was given only for cubic lattices. In this paper, the NS-FDTD method is extended to the rectangular lattices and the numerical dispersion characteristic and the stability condition are derived. From the analysis for the stability condition, it is found that the stability condition in the present method is larger than those for the FDTD method and the FDTD(2, 4) method. From the analysis of the dispersion characteristic, it is shown that the present method has much higher accuracy than the FDTD method whether the lattices are cubic or rectangular. An analysis of a waveguide model is carried out in which the NS-FDTD method and the FDTD method are mixed. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 85(1): 22–30, 2002 [ABSTRACT FROM AUTHOR]

This paper considers the electromagnetic propulsion of a body radiating directed electromagnetic waves. As the source of electromagnetic waves, a system consisting of two electric dipoles is chosen. The electromagnetic propulsion this system receives from the surrounding space is theoretically analyzed and discussed. This propulsion is related to the near field formed by the dipoles and exhibits the maximum propulsion at a characteristic dipole spacing. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(4): 31–39, 2000 [ABSTRACT FROM AUTHOR]

3D photonic crystals can produce a number of fascinating optical devices utilizing the band gap, the dispersive passband, and unisotropic band structure. We previously proposed a process for fabricating a 3D periodic nanostructure which can behave as photonic crystals. The key technique in the process is the deposition of a multilayer by bias sputtering replicating periodically a corrugated layer pattern, which is named the autocloning effect. This paper reviews our recent works on 3D photonic crystals: the mechanism of the autocloning effect, propagation analysis in the 3D photonic crystal by an FDTD method, and applications such as plane-normal waveguides or wavelength-selective filters. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(9): 43–52, 1999 [ABSTRACT FROM AUTHOR]

Vertical photonics is the technique of direct integration of optical functional devices or their integration into optical fibers. In optical fiber systems, it is usually very difficult to match the modes of optical fibers to those of minute devices or to adjust their positions accurately. To solve such connection problems, the expanded core fibers are used, the aperture of the device is enlarged, and the optical path is shortened. In this paper, the concept of vertical photonics is discussed and the present status of the basic components (wavelength filters, polarizers, polarization splitters, etc.) and optical devices (isolators, optical switches, wavelength tunable filters, amplifiers, etc.) is reviewed. [ABSTRACT FROM AUTHOR]

Semiconductor materials are suitable for monolithic photonic integrated circuits since they can realize almost all the necessary photonic functions such as light emission, light amplifications, light detection, light modulation/switching and optical waveguiding. Additionally, since the figure of merit of various physical effects used to realize the foregoing functions is large and since it is easy to arrange the spatial region to generate these effects into compact and convenient shape, it is advantageous for small size and high performance. The research and development of photonic integrated circuits utilizing semiconductors has an accumulation at history, knowledge, and technology, already spanning a quarter of a century. Although it has required a longer time before it becomes practical than the electronic integrated circuits, it has shown rapid progress since the end of 1980's. This is attributed to the combination of the driving force from the needs point of view based on the advances in semiconductor laser technology, introduction, and spreading of quantum well structures and evolution of processing technology such as epitaxial growth methods and the strong demand from the needs point of view toward all optical telecommunication networks where not only trunk lines but also switching nodes and subscriber lines use an optical wave. This paper reviews the present status of photonic devices and circuits obtained by monolithic integration of semiconductor element devices by classifying them into light emitters, optical switches, and combiners/splitters. Finally, the necessity of semiconductor integrated photonic systems is set forth toward the future. [ABSTRACT FROM AUTHOR]

This paper proposes a new architecture of photonic ATM switch for the purpose of eventually moving beyond the terabits-per-second (Tbps) level throughout ATM operation. The proposed architecture is based on vertical-to-surface transmission electro-photonic devices (VSTEPs) which can be used both as an optical buffer memory and as an optical self-routing circuit. Since VSTEP is an integrated two-dimensional array, the VSTEP-based optical buffer memory using massively parallel optical interconnections based on the free-space optical beam propagation is an effective solution to achieve ultrahigh throughput in the buffer. The optical cell signal - in the proposed optical buffer memory can reach about 10 Gbps. By using the VSTEP function as the optical header-driven gates in a two-dimensional array, the high-speed and large-capacity optical self- muting circuit can be fabricated without being limited by the electric control circuit operation. in the proposed optical self-routing circuit, priority control to prevent collision among cell signals at the output port in the case of cell signal contention can easily be achieved. The numbers of possible input and output ports in the self-muting circuit are estimated to be around 100. An optical header is inserted at the front of the ATM cell signal for processing at the self-routing circuit. To reduce the overhead of the optical header, a wavelength-division technique also is proposed for the self-routing circuit. Finally, experiments on operations of both the buffer memory and the self-routing circuit with priority control for 1.6-Gbps optical cells are carried out successfully. [ABSTRACT FROM AUTHOR]

It is important to evaluate the crystalline quality of an ion-implanted layer after annealing. The evaluation method must be simple and nondestructive. In this study, a silicon substrate was implanted with various doses of P+ of Si+ at various acceleration energies and the crystalline quality of the implanted layer after annealing was evaluated by photothermal deflection spectroscopy (PDS). The results were compared with those obtained by cross-sectional TEM observation, RBS, resistivity and EST measurements. Hence it was found that the PDS method can evaluate the amorphous layer thickness formed by ion implantation and the quality of crystalline defects as a change of additional absorption. The PDS method can detect micro-crystalline defects and changes in crystalline structure due to annealing which are not observed by the RBS and resistivity measurements. Because the PDS method is relatively simple and nondestructive, it is effective in evaluating the crystalline quality of an implanted layer. [ABSTRACT FROM AUTHOR]

The design method for the polarization-maintaining optical fiber with two hollow circular pits across the core-clad interface was investigates under the following two conditions: (1) the total dispersion for one of nondegenerated HE11 modes is zero simultaneously at the two wavelengths of 1.30 µm and 1.55 µm (the zero dispersion condition); and (2) the modal birefringence (≈B) is maximum. The polarization-maintaining optical fibers with hollow circular pits across the core-clad interface are the structure which can maximize the modal birefringence in angularly nonuniform refractive index profiles in the case where no dispersion is considered. To satisfy the conditions for (1) and (2), the relative index difference of the core and the clad Δ1, the normalized minimum distance between the core center and the pit periphery D[...(R...-a...)/a..., R0: the distance between the core center and the pit center, a1: the core radius, a3 : the pit radius, and the normalized pit radius ( = a3/a1 are used as parameters. The principal results obtained in this paper are as follows. (1) If D is decreased, B also reduces since a3/a1 must also be decreased for the zero dispersion condition. (2) B can be maximized if two hollow pits are in contact with the core periphery (D =1.0). (3) When Δ1 to 0.5 to 1.5 percent, the attained maximum value of B is 0.75 x 10-4 to 2.23 x -4. [ABSTRACT FROM AUTHOR]