A trinary-phased array, in which a phase quantization unit of phase shifters is 120 degrees is examined. The phase quantization unit of 120 degrees is the roughest value in practical phased array applications. Despite its rough phase quantization, the sidelobe level of less than -9 dB is attained by a genetic algorithm approach.

A new dynamic programming (DP) based algorithm for monotonic and continuous two-dimensional warping (2DW) is presented. This algorithm searches for the optimal pixel-to-pixel mapping between a pair of images subject to monotonicity and continuity constraints with by far less time complexity than the algorithm previously reported by the authors. This complexity reduction results from a refinement of the multi-stage decision process representing the 2DW problem. As an implementation technique, a polynomial order approximation algorithm incorporated with beam search is also presented. Theoretical and experimental comparisons show that the present approximation algorithm yields better performance than the previous approximation algorithm.

A novel method is proposed to calculate the distributed coupling of dual-modes in a circular resonator. New theoretical expressions are devised to accumulate the infinitesimal coupling between orthogonal modes and their validity is justified by the FD-TD analysis and experiments. The distributed coupling concept of a circular disk resonator is applied to a square disk resonator to calculate its resonant frequency. We have fabricated two types of low-profile dual-mode square dielectric disk resonator BPF, using high dielectric constant material (εr = 93) having a dimension of 5 mm 5 mm 1 mm. The filter characteristics are explained by the transmission line circuit model.

Wavelength Division Multiplex (WDM) photonic networks are expected as key for global communication infrastructure. The accurate measurement methods for AWG-MUX/DMUX are desirable for WDM network design. We measured a transfer function matrix of an AWG-MUX to find that polarization mode dispersion (PMD) and polarization dependent loss (PDL) shows the bandpass characteristics, which may limit the maximum size and the bit rate of the system. These bandpass characteristics of PMD and PDL are reproduced by a simple AWG-MUX model: The phase constant difference of 0.5% between orthogonal modes in arrayed waveguides is sufficient to obtain the measured passband characteristics of PMD and PDL. We find phase distribution difference between two orthogonal modes in the arrayed waveguide grating gives arise to complex PMD.

Optoelectronic hybrid integration is a promising technology for realizing the optical components needed in optical transmission, switching, and interconnection systems that use wavelength division multiplexing (WDM) and time division multiplexing (TDM). We have already developed versatile optical hybrid integrated modules using a silica-based planar lightwave circuit (PLC) platform. However, these modules consist solely of the optoelectronic semiconductor devices such as laser diodes (LDs) and photo diodes (PDs) and monolithic optoelectronic integrated circuits (OEICs). To carry out high-speed and versatile electric signal processing functions in future network systems, it is necessary to install semiconductor electrical integrated circuits (ICs) on a PLC platform. In this paper, we describe novel technologies for high-speed PLC platforms which make it possible to assemble both ICs and optoelectronic devices. Using these technologies, we fabricated a two-channel hybrid integrated optical transmitter module which is hybrid integrated with an LD array chip and an LD driver IC. On this PLC platform, we use microstrip lines (MSLs) to drive the LD driver IC. We also considered the effect of heat interference on the LD array chip caused by the LD driver IC when designing the layout of the chip assembly region. The LD array chip and the LD driver IC were flip-chip bonded with solder bumps of a different material to avoid any deterioration in the coupling efficiency of the LD array chip. The optical transmitter module we fabricated operated successfully at 9 Gbit/s non-return-zero (NRZ) signal. This approach using a PLC platform for the hybrid integration of an LD array chip and an LD driver IC will carry forward the development of high-speed optoelectronic modules with both optical and electrical signal processing functions.

Wavelength Division Multiplex (WDM) photonic networks are expected as key for global communication infrastructure. The accurate measurement methods for AWG-MUX/DMUX are desirable for WDM network design. We measured a transfer function matrix of an AWG-MUX to find that polarization mode dispersion (PMD) and polarization dependent loss (PDL) shows the bandpass characteristics, which may limit the maximum size and the bit rate of the system. These bandpass characteristics of PMD and PDL are reproduced by a simple AWG-MUX model: The phase constant difference of 0.5% between orthogonal modes in arrayed waveguides is sufficient to obtain the measured passband characteristics of PMD and PDL. We find phase distribution difference between two orthogonal modes in the arrayed waveguide grating gives arise to complex PMD.

In this paper a new snake model for image morphing with semiautomated delineation which depends on Hermite's interpolation theory, is presented. The snake model will be used to specify the correspondence between features in two given images. It allows a user to extract a contour that defines a facial feature such as the lips, mouth, and profile, by only specifying the endpoints of the contour around the feature which we wish to define. We assume that the user can specify the endpoints of a curve around the features that serve as the extremities of a contour. The proposed method automatically computes the image information around these endpoints which provides the boundary conditions. Then the contour is optimized by taking this information into account near its extremities. During the iterative optimization process, the image forces are turned on progressively from the contour extremities toward the center to define the exact position of the feature. The proposed algorithm helps the user to easily define the exact position of a feature. It may also reduce the time required to establish the features of an image.

In this paper, the computational issue in the problem of learning Bayesian belief networks (BBNs) based on the minimum description length (MDL) principle is addressed. Based on an asymptotic formula of description length, we apply the branch and bound technique to finding true network structures. The resulting algorithm searches considerably saves the computation yet successfully searches the network structure with the minimum value of the formula. Thus far, there has been no search algorithm that finds the optimal solution for examples of practical size and a set of network structures in the sense of the maximum posterior probability, and heuristic searches such as K2 and K3 trap in local optima due to the greedy nature even when the sample size is large. The proposed algorithm, since it minimizes the description length, eventually selects the true network structure as the sample size goes to infinity.

Optoelectronic hybrid integration is a promising technology for realizing the optical components needed in optical transmission, switching, and interconnection systems that use wavelength division multiplexing (WDM) and time division multiplexing (TDM). We have already developed versatile optical hybrid integrated modules using a silica-based planar lightwave circuit (PLC) platform. However, these modules consist solely of the optoelectronic semiconductor devices such as laser diodes (LDs) and photo diodes (PDs) and monolithic optoelectronic integrated circuits (OEICs). To carry out high-speed and versatile electric signal processing functions in future network systems, it is necessary to install semiconductor electrical integrated circuits (ICs) on a PLC platform. In this paper, we describe novel technologies for high-speed PLC platforms which make it possible to assemble both ICs and optoelectronic devices. Using these technologies, we fabricated a two-channel hybrid integrated optical transmitter module which is hybrid integrated with an LD array chip and an LD driver IC. On this PLC platform, we use microstrip lines (MSLs) to drive the LD driver IC. We also considered the effect of heat interference on the LD array chip caused by the LD driver IC when designing the layout of the chip assembly region. The LD array chip and the LD driver IC were flip-chip bonded with solder bumps of a different material to avoid any deterioration in the coupling efficiency of the LD array chip. The optical transmitter module we fabricated operated successfully at 9 Gbit/s non-return-zero (NRZ) signal. This approach using a PLC platform for the hybrid integration of an LD array chip and an LD driver IC will carry forward the development of high-speed optoelectronic modules with both optical and electrical signal processing functions.

This paper describes a new reconfigurable processor architecture called REMARC (Reconfigurable Multimedia Array Coprocessor). REMARC is a small array processor that is tightly coupled to a main RISC processor. It consists of a global control unit and 64 16-bit processors called nano processors. REMARC is designed to accelerate multimedia applications, such as video compression, decompression, and image processing. These applications typically use 8-bit or 16-bit data therefore, each nano processor has a 16-bit datapath that is much wider than those of other reconfigurable coprocessors. We have developed a programming environment for REMARC and several realistic application programs, DES encryption, MPEG-2 decoding, and MPEG-2 encoding. REMARC can implement various parallel algorithms which appear in these multimedia applications. For instance, REMARC can implement SIMD type instructions similar to multimedia instruction extensions for motion compensation of the MPEG-2 decoding. Furthermore, the highly pipelined algorithms, like systolic algorithms, which appear in motion estimation of the MPEG-2 encoding can also be implemented efficiently. REMARC achieves speedups ranging from a factor of 2.3 to 21.2 over the base processor which is a single issue processor or 2-issue superscalar processor. We also compare its performance with multimedia instruction extensions. Using more processing resources, REMARC can achieve higher performance than multimedia instruction extensions.

The hybrid electrical/optical multi-chip integration technique for optical modules for optical network system has been developed. Employing the technique, a 44 broadcast-and-select type optical matrix switch module has been realized. The module consists of four sets of silica waveguide 1 : 4 splitters/4 : 1 combiners, four 4-channel arrays of polarization insensitive semiconductor optical amplifiers with spot-size converters as optical gates, printed wiring chips for electrical wiring and single mode fibers for optical signal interface on planar waveguide platform fabricated by atmospheric pressure chemical vapor deposition. All the gates and the wiring chips were mounted precisely onto the platform at once in flip-chip manner by self-align technique using AuSn solder bumps. Coupling loss between the waveguide and the SOA gate was estimated to be 4.5 dB. Averaged fiber-to-fiber signal gain, on-off ratio and polarization dependent loss for each of the signal paths was 7 dB 2 dB, more than 40 dB and 0.5 dB, respectively. High speed 10 Gb/s photonic cell switching as short as 2 nsec has been successfully achieved.

State of the arts on guided-wave optical switch arrays are reviewed. In this paper, electro-optic Ti:LiNbO3 devices are mainly described in comparison with crosspoint switch element structures and switch array architectures. Packaging technologies and stability problems are discussed for practical system applications. Recent development on other materials such as semiconductor waveguides, thermo-optic glass/polymer waveguides are also reviewed briefly.

A 116 arrayed waveguide grating multiplexer operating around 1550 nm has been realized using newly synthesized fluorinated poly(arylene ethers). The channel spacing is 0.8 nm (100 GHz). The insertion loss of the multiplexer is 17-20 dB and the cross talk is less than -15 dB. The propagation loss of a rib waveguide is less than 0.5 dB/cm at 1550 nm.

This paper reviews the hyper-media photonic information network (HM-PIN) concept as a candidate of innovative future networks based on photonic technologies. The HM-PIN having a universal network interface integrates a variety of information services: telecommunications, newspapers, magazines, TV broadcasts and the growing collection of information servers. This network fundamentally offers three items: (1) bi-directional real-time channels with 10-Mbit/s-class or higher bit rate, (2) multipoint connections including multicasting/broadcasting, (3) high accessibility to information. These items are derived from the constraints of the conventional telephone networks and the Internet. By applying photonic technologies, the HM-PIN can be implemented as follows: The local network (the service platform) of the HM-PIN can be achieved by using a wavelength-division-multiplexing (WDM) broadcast-and-select (B&S) architecture that offers broadband multipoint connections (one-to-many, many-to-many) based on an inherent full-mesh topology. The WDM B&S local network will be able to support 10,000 to 100,000 channels (each with 10-Mbit/s or more bandwidth) by using optical and electrical multiplexing techniques. The backbone network can be constructed by combining photonic asynchronous transfer mode (ATM) switching systems and WDM transmission systems (including cross-connects). Two deployment scenarios of the HM-PIN (cost-oriented and service-oriented deployment scenarios) are also described for smoothly introducing the HM-PIN even before the cost issue is solved. The HM-PIN based on photonic technologies will be a future network service platform that greatly enhances communication services.

This paper proposes a 3-stage ATM switch architecture that uses optical WDM (wavelength division multiplexing) grouped links and dynamic bandwidth sharing. The proposed architecture has two features. The first is the use of WDM technology which makes the number of cables used in the system proportional to system size. The second is the use of dynamic bandwidth sharing among WDM grouped links. This prevents the statistical multiplexing gain offered by WDM from falling even if switching system becomes large. A performance evaluation confirms the scaleability and cost-effectiveness of the proposed architecture. It is scaleable in terms of the number of cables and admissible load. We show how the appropriate wavelength signal speed can be determined to implement the switch in a cost-effective manner. Therefore, the proposed architecture will suit future high-speed multimedia ATM networks.

An optical cell buffer (OCB) for use in photonic ATM switch, is needed in order to resolve contention between optical cells. A 320-Gb/s-throughput switch system with 32 wavelength channels requires a buffer size of 13 and a wavelength bandwidth of 25 nm. We developed an optical cell buffer with a four-nested-taps configuration and fabricated it with electroabsorption gates and gain clamped optical amplifiers. The output level variation, which determines the stability of operating condition, is less than 2.4 dB under typical conditions and the insertion loss variation is suppressed to within 5 dB. This OCB can be used in a 320-Gb/s photonic ATM switch.

The frequency-offset estimation of a wireless asynchronous transfer mode (ATM) modem based on the orthogonal frequency division multiplexing (OFDM) is discussed. For burst synchronization operating under the time-division multiple access (TDMA) medium access control (MAC), an OFDM preamble using a multistage frequency-offset estimation technique is proposed and shown to have a good accuracy with a large estimation range. And also an averaged decision-directed channel estimation (ADDCE) technique suitable for burst data is proposed.

This paper describes the implementation and demonstration of local networks for the hyper-media photonic information network (HM-PIN), a candidate for the information service platform offering broadcast and telecommunication services. In addition, the feasibility of the HM-PIN is also demonstrated using prototype local network systems. This local network adopts architecture based on wavelength-division-multiplexing (WDM) and broadcast-and-select (B&S) switching, and supports all HM-PIN services except inter-local-network communication. The major issues of this proposed network are the technologies that support many broadcast channels and reduce channel selection cost. This paper also considers the combination of WDM technology and three alternatives: electrical TDM, subcarrier multiplexing (SCM or electrical FDM), and optical TDM (O-TDM). Three 128 ch (8 wavelengths 16 channels) WDM B&S prototype systems are built to demonstrate the feasibility of the proposed HM-PIN. In WDM/SCM, 30 and 20 Mb/s channels are realized as 16-QAM and 64-QAM, and 155 Mb/s channels are realized by WDM/TDM. Moreover, these three prototypes were connected to form a small HM-PIN and applications such as video distribution and IP datagram cut-through are demonstrated. Furthermore, the delay and throughput of the HM-PIN are evaluated by connecting a local network to a 200-km WDM-ring backbone network. Our discussions and demonstrations confirm the impact and feasibility of the proposed hyper-media photonic information network.

To enhance the extinction ratio (ER) of NRZ-to-inverted-RZ converter based on cross-gain compression of a semiconductor optical amplifier (SOA), a modified terahertz optical asymmetric demultiplexer (TOAD) is cascaded. ER is improved from 1.6-6.7 dB to 5.4-14.5 dB, depending on the intensity of input optical NRZ signal. The proposed NRZ-to-inverted-RZ converter enhances and regulates ER to a high value (14.5 dB) for very wide optical NRZ signal intensity range.

This paper proposes a fast synchronization scheme with a short preamble signal for high data rate wireless LAN systems using orthogonal frequency division multiplexing (OFDM). The proposed OFDM burst format for fast synchronization and the demodulator for the proposed OFDM burst format are described. The demodulator, which offers automatic frequency control and symbol timing detection, enables us to shorten the preamble length to one quarter that of a conventional one. Computer simulation results show that the degradation in required Eb/N0 due to the synchronization scheme is less than 1 dB in a selective Rayleigh fading channel.