We have fabricated a polymer solid-state microstructure for optical application by two-photon-induced polymerization technique. The photopolymerization resin contains conventional laser-dye and dendrimer. A dendrimer can encapsulate the laser-dyes, limiting cluster formation and intermolecular energy transfer, and promising a high level of optical gain. The effect can be extended to prepare an optically active microstructure using the two-photon-induced polymerization technique. We fabricated a polymeric microcavity, which consisted of < 400 nm-linewidth strips arranged in layer-by-layer structure. The periodic variation in the refractive index gave rise to Bragg reflection. A laser emission was measured in the microcavity under optical excitation. The spectral linewidth was about 0.1 nm above the lasing threshold. We investigate both the material functions in the molecular scale and controlling the device structure for desired applications such as a polymer distributed feedback structure.

In this paper, we describe detailed experimental demonstrations of blue/violet light generation by the injection of ultrashort optical pulses into photonic crystal fibers (PCFs). Two lightwaves appear one on each side of the injected pulses in the spectral domain. They simultaneously evolve in the PCFs, changing their center wavelengths so as to spectrally stand apart from each other. Such behaviors are explained on the basis of the theory of nonlinear optics. The final center-wavelength difference between the two lightwaves at the end of the PCFs, depending on the power density of the injected pulse, is increased up to a limit imposed by the PCFs. Owing to this increase, the shorter wavelength limit reaches approximately 400 nm, which shows that short-pulse injection in PCFs is a promising method of realizing simple blue/violet light sources.

We report on a channel drop filter with a mode gap in the propagating mode of a photonic crystal slab that was fabricated on silicon on an insulator wafer. The results, simulated with the 3-dimensional finite-difference time-domain and plane-wave methods, demonstrated that an index-guiding mode for the line defect waveguide of a photonic crystal slab has a band gap at wave vector k = 0.5 for a mainly TM-like light-wave. The mode gap works as a distributed Bragg grating reflector that propagates the light-wave through the line defect waveguide, and can be used as an optical filter. The filter bandwidth was varied from 1-8 nm with an r/a (r: hole radius, a: lattice constant) variation around the wavelength range of 1550-1600 nm. We fabricated a Bragg reflector with a photonic crystal line-defect waveguide and Si-channel waveguides and by measuring the transmittance spectrum found that the Bragg reflector caused abrupt dips in transmittance. These experimental results are consistent with the results of the theoretical analysis described above. Utilizing the Bragg reflector, we fabricated channel dropping filters with photonic crystal slabs connected between channel waveguides and demonstrated their transmittance characteristics. They were highly drop efficient, with a flat-top drop-out spectrum at a wavelength of 1.56 µm and a drop bandwidth of 5.8 nm. Results showed that an optical add-drop multiplexer with a 2-D photonic crystal will be available for application in WDM devices for photonic networks and for LSIs in the near future.

In January 2005, an open evaluation of corpus-based text-to-speech synthesis systems using common speech datasets, named Blizzard Challenge 2005, was conducted. Nitech group participated in this challenge, entering an HMM-based speech synthesis system called Nitech-HTS 2005. This paper describes the technical details, building processes, and performance of our system. We first give an overview of the basic HMM-based speech synthesis system, and then describe new features integrated into Nitech-HTS 2005 such as STRAIGHT-based vocoding, HSMM-based acoustic modeling, and a speech parameter generation algorithm considering GV. Constructed Nitech-HTS 2005 voices can generate speech waveforms at 0.3RT (real-time ratio) on a 1.6 GHz Pentium 4 machine, and footprints of these voices are less than 2 Mbytes. Subjective listening tests showed that the naturalness and intelligibility of the Nitech-HTS 2005 voices were much better than expected.

In the past twenty years, there were only a few constructions for Boolean functions with nonlinearity exceeding the quadratic bound 2n-1-2(n-1)/2 when n is odd (we shall call them Boolean functions with very high nonlinearity). The first basic construction was by Patterson and Wiedemann in 1983, which produced unbalanced function with very high nonlinearity. But for cryptographic applications, we need balanced Boolean functions. Therefore in 1993, Seberry, Zhang and Zheng proposed a secondary construction for balanced functions with very high nonlinearity by taking the direct sum of a modified bent function with the Patterson-Wiedemann function. Later in 2000, Sarkar and Maitra constructed such functions by taking the direct sum of a bent function with a modified Patterson-Wiedemann function. In this paper, we propose a new secondary construction for balanced Boolean functions with very high nonlinearity by recursively composing balanced functions with very high nonlinearity with quadratic functions. This is the first construction for balanced function with very high nonlinearity not based on the direct sum approach. Our construction also have other desirable properties like high algebraic degree and large linear span.

In this paper, we propose an algorithm that solves the node-to-node disjoint paths problem in n-burnt pancake graphs in polynomial-order time of n. We also give a proof of its correctness as well as the estimates of time complexity O(n3) and the maximum path length 3n+4. We conducted a computer experiment for n=2 to 100 to measure the average performance of our algorithm. The results show that the average time complexity is O(n3.0) and the maximum path length is 3n+4.

The letter describes a phase perturbation attack to the Discrete Fourier Transform (DFT) and Phase Shift Keying (PSK) based watermarking scheme which is proposed in [3]. In that paper the watermark information is embedded in the phase of the DFT coefficients. But this kind of PSK based watermarking scheme is very vulnerable to the phase perturbation attack, when some noise is added on the phase of the DFT coefficients, the watermark can't be correctly extracted anymore, while the quality degradation of the attacked watermarked image is visually acceptable.

In this paper, we propose new models for directly evaluating DPA leakage from logic information in CMOS circuits. These models are based on the transition probability for each gate, and are naturally applicable to various actual devices for simulating power analysis. Furthermore, we demonstrate the weakness of previously known hardware countermeasures for both our model and FPGA and suggest secure conditions for the hardware countermeasure.

A Non-Uniform Discrete Multitone (DMT) transceiver employing an octave spaced quadrature mirror filter (QMF) bank, can be used to overcome the problem of channel noise enhancement in the zero-forcing (ZF) equalization technique. In this letter, performance of the Non-Uniform DMT system is analyzed. A study of the crosstalk between sub-channels due to non-ideal filter banks is also presented. Crosstalk analysis is based upon the bit error rate (BER) performance versus the QMF order in a standadard ADSL channel. Performance comparison of the Non-Uniform DMT transceiver and a conventional DMT system is given, and it is shown that the Non-Uniform DMT transceiver displays slight improvement over the conventional DMT system for the filters of higher order.

Complex thin oxide films with electro-optic (EO) properties are promising for use in advanced optical devices because of their large EO effect. We developed a method of aerosol deposition (AD) for fabricating EO films. The mechanism for AD is based on the solidification by impact of submicron particles onto a substrate. Since particles in AD films preserve their crystalline structure during the formation of film, epitaxial growth is not necessary for exhibiting the EO effect. Highly transparent Pb(Zr, Ti)O3 films, which have acceptable transmittance loss for use as optical devices, were directly deposited on glass substrates by AD. We found the Pb(Zr, Ti)O3 film by AD produced a fairly high EO coefficient (>150 pm/V), approximately 10 times larger than that of LiNbO3. A Fabry-Perot (FP) optical modulator was developed with EO films fabricated by AD. We demonstrated the modulation of optical intensity with an electrical field applied to an EO film made of ferroelectric Pb (Zr, Ti)O3.

A new 1.25-Gb/s digitally-controlled dual-loop clock and data recovery circuit is realized. To overcome jitter problems caused by the phase resolution limit, the CDR has two phase generation stages: coarse generation by a phase interpolator and fine generation by a variable delay buffer. The performance of the proposed CDR was verified by behavioral and transistor-level simulations. A prototype CDR chip fabricated with 0.18 µm CMOS process shows error-free operation for 400 ppm frequency offset. The chip occupies 165255 µm2 and consumes 17.8 mW.

A semi-supervised classification method is presented. A robust unsupervised spectral mapping method is extended to a semi-supervised situation. Our proposed algorithm is derived by linearization of this nonlinear semi-supervised mapping method. Experiments using the proposed method for some public benchmark data reveal that our method outperforms a supervised algorithm using the linear discriminant analysis for the iris and wine data and is also more accurate than a semi-supervised algorithm of the logistic GRF for the ionosphere dataset.

A waveguide-based surface plasmon resonance (SPR) sensor with an adsorbed layer is analyzed using the beam-propagation method. For two-dimensional (2-D) models, numerical results show that the change in thickness of the adsorbed layer placed on the metal leads to a significant shift of the maximum absorption wavelength. Through eigenmode analysis, the maximum absorption wavelength is found to be consistent with the cutoff wavelength of the second-order surface plasmon mode. The designed 2-D sensor shows an absorption wavelength shift from 0.595 to 0.603 µm, when the analyte refractive index is increased from 1.330 to 1.334. After a basic investigation using the 2-D models, we next study 3-D models. When the metal with the absorbed layer is wide enough to cover the core region, the 3-D results are similar to the 2-D results. However, as the metal width is reduced, the absorption wavelength shifts toward a shorter wavelength and the sensitivity to the refractive index change degrades gradually. The degradation of the sensitivity is considerable when the metal width is narrower than the core width. As a result, the metal width of the practical SPR sensor should be slightly wider than the core width so as to maintain the sensitivity corresponding to that obtained for the 2-D model.

This paper presents a secure and simple content-based digital signature method for verifying the image authentication under JPEG, JPEG2000 compression and scaling based on a novel concept named lowest authenticable difference (LAD). The whole method, which is extended from the crypto-based digital signature scheme, mainly consists of statistical analysis and signature generation/verification. The invariant features, which are generated from the relationship among image blocks in the spatial domain, are coded and signed by the sender's private key to create a digital signature for each image, regardless of the image size. The main contributions of the proposed scheme are: (1) only the spatial domain is adopted during feature generation and verification, making domain transformation process unnecessary; (2) more non-malicious manipulated images (JPEG, JPEG2000 compressed and scaled images) than related studies can be authenticated by LAD, achieving a good trade-off of image authentication between fragile and robust under practical image processing; (3) non-malicious manipulation is clearly defined to meet closely the requirements of storing images or sending them over the Internet. The related analysis and discussion are presented. The experimental results indicate that the proposed method is feasible and effective.

ID-SP-M4M scheme means ID-based series-parallel multisignature schemes for multi-messages. In this paper, we investigate series-parallel multisignature schemes for multi-messages and propose an ID-SP-M4M scheme based on pairings in which signers in the same subgroup sign the same message, and those in different subgroups sign different messages. Our new scheme is an improvement over the series-parallel multisignature schemes introduced by Doi et al.[6]-[8] and subsequent results such as the schemes proposed by Burmester et al.[4] and the original protocols proposed by Tada [20],[21], in which only one message is to be signed. Furthermore, our ID-SP-M4M scheme is secure against forgery signature attack from parallel insiders under the BDH assumption.

This paper presents a scalable FPGA/ASIC implementation architecture for high-speed parallel table-lookup-coding using multi-ported content addressable memory, aiming at facilitating effective table-lookup-coding solutions. The multi-ported CAM adopts a Flexible Multi-ported Content Addressable Memory (FMCAM) technology, which represents an effective parallel processing architecture and was previously reported in [1]. To achieve a high-speed parallel table-lookup-coding solution, FMCAM is improved by additional schemes for a single search mode and counting value setting mode, so that it permits fast parallel table-lookup-coding operations. Evaluation results for Huffman encoding within the JPEG application show that a synthesized semi-custom ASIC implementation of the proposed architecture can already reduce the required clock-cycle number by 93% in comparison to a conventional DSP. Furthermore, the performance per area unit, measured in MOPS/mm2, can be improved by a factor of 3.8 in comparison to parallel operated DSPs. Consequently, the proposed architecture is very suitable for FPGA/ASIC implementation, and is a promising solution for small area integrated realization of real-time table-lookup-coding applications.

This paper proposes a new countermeasure, Random Switching Logic (RSL), against DPA (Differential Power Analysis) and Second-Order DPA at the logic level. RSL makes a signal transition uniform at each gate and suppresses the propagation of glitch to allow power consumption to be independent of predictable data. Furthermore, we implement basic logic circuits on the FPGA (Field Programmable Gate Array) by using RSL, and evaluate the effectiveness. As a result, we confirm the fact that the secure circuit can be structured against DPA and Second-Order DPA.

This paper presents two hardware-friendly low-power oriented fast motion estimation (ME) algorithms and their VLSI implementations. The basic idea of the proposed partial distortion sorting (PDS) algorithm is to disable the search points which have larger partial distortions during the ME process, and only keep those search points with smaller ones. To further reduce the computation overhead, a simplified local PDS (LPDS) algorithm is also presented. Experiments show that the PDS and LPDS algorithms can provide almost the same image quality as full search only with 36.7% computation complexity. The proposed two algorithms can be integrated into different FSBMA architectures to save power consumption. In this paper, the 1-D inter ME architecture [12] is used as an detailed example. Under the worst working conditions (1.62 V, 125) and 166 MHz clock frequency, the PDS algorithm can reduce 33.3% power consumption with 4.05 K gates extra hardware cost, and the LPDS can reduce 37.8% power consumption with 1.73 K gates overhead.

It is known that for any general access structure, a secret sharing scheme (SSS) can be constructed from an (m,m)-threshold scheme by using the so-called cumulative map or from a (t,m)-threshold SSS by a modified cumulative map. However, such constructed SSSs are not efficient generally. In this paper, a new method is proposed to construct a SSS from a (t,m)-threshold scheme for any given general access structure. In the proposed method, integer programming is used to derive the optimal (t,m)-threshold scheme and the optimal distribution of the shares to minimize the average or maximum size of the distributed shares to participants. From the optimality, it can always attain lower coding rate than the cumulative maps because the cumulative maps cannot attain the optimal distribution in many cases. The same method is also applied to construct SSSs for incomplete access structures and/or ramp access structures.

We present the use of a Modified Generalized Hough Transform (MGHT) and deformable contours for image data retrieval where a given contour, gray-scale, or color template image can be detected in the target image, irrespective of its position, size, rotation, and smooth deformation transformations. Potential template positions are found in the target image using our novel modified Generalized Hough Transform method that takes measurements from the template features by extending a line from each edge contour point in its gradient direction to the other end of the object. The gradient difference is used to create a relationship with the orientation and length of this line segment. Potential matching positions in the target image are then searched by also extending a line from each target edge point to another end along the normal, then looking up the measurements data from the template image. Positions with high votes become candidate positions. Each candidate position is used to find a match by allowing the template to undergo a contour transformation. The deformed template contour is matched with the target by measuring the similarity in contour tangent direction and the smoothness of the matching vector. The deformation parameters are then updated via a Bayesian algorithm to find the best match. To avoid getting stuck in a local minimum solution, a novel coarse-and-fine model for contour matching is included. Results are presented for real images of several kinds including bin picking and fingerprint identification.