To study material dispersion effects on transmission characteristics in optical fibers, material dispersion properties in GeO2-P2O5-doped silica optical fibers were determined as a function of GeO2 doping concentration. The material dispersion properties were evaluated from pulse delay measurement with nanosecond pulses in a 0.60-1.65 µm spectral region generated by a nanosecond optical pulse radiator. From the measured delay, refractive index of core glass, material group index, material dispersion, zero-material-dispersion wavelength and zero-dispersion wavelength in a single mode fiber have been determined as a function of GeO2 doping concentration in the range 4.1 to 19.2 mol %. By extrapolating present data in GeO2-P2O5-SiO2 ternaries, material dispersion properties in fused GeO2 glass have been predicted. The zero-material-dispersion wavelength in fused GeO2 glass can be estimated to be 1.68 0.03 µm.

It is shown that we can simultaneously make both of Zech's logarithm table and trace table in a finite field by using a feedback shift register which generates a pseudo-random sequence. Convenient method for the initial loading of the feedback shift register is given.

A Josephson computer device called a carousel SQUID is proposed which uses an interferometer capable to be used as both a memory cell and logic gate. The principle of the operation of carousel SQUIDs is the rotation of a fluxoid quantum in the device, which makes the device to have excellent performances as computer ones. The memory cell stores one fluxoid quantum and is non-destructive read-out one. For the logic gate, the current gain is much larger than unity and input signal is isolated from the logic gate.

This paper describes an optical demultiplexer whose diffracted light beams are directly detected by a monolithic linear array of six silicon pin photo-diodes for the 0.8 µm wavelength region. The demultiplexer has 6 channels whose wavelength spacing is 23 nm. Insertion losses and crosstalks were less than 2.1 dB and -25 dB, respectively.

Requirements for a telecommunications network are becoming diversified in accordance with progress in social activities. To meet flexibly variable requirements, the telecommunications network should be provided with high capability exchange systems. For such a purpose, the stored program controlled (SPC) switching system may play a key role. In order to process calls in the telecommunications network environment, a signaling system is inevitable. In the telecommunications network, composed of electronic switching systems, the interoffice signaling system should be efficient when handled by a stored program. This paper describes modeling of interoffice signal processing and formulates parameters evaluating signal processing effectiveness. As a numerical example, multifrequency (MF) and common channel (CC) signal processings for a 9 digit transit call in a toll originating switching system served by D-10, N.T.T.'s commercial switching system, are analyzed in an assumed environment of the present analog and the future digital telecommunications network. From the result of this analysis, the paper concludes that a common channel signaling system is effective in the present analog network from the SPC viewpoint. If a digital environment is assumed in the future, a multifrequency-like individual channel signaling system is considered to be effective due to the improvements in dialed number transfer, inherent easy channel state recognition and no necessity for a continuity test. It is also suggested based on the interoffice signal processing analysis to use a common channel signaling system as an interoffice data link between switching offices and a data base, where data on routing (selected speechpath link) or subscriber are stored.

Static characteristics of InGaAsP/InP double-hetero-structure laser diodes with stripe geometry have been examined. Relation between stripe width and "kink power", Pk, where a kink appears in the light output vs. current curve, is demonstrated experimentally. It is shown that a 7 µm-wide stripe laser diode exhibits the stable fundamental transverse mode oscillation as well as the single longitudinal mode oscillation. Growth rate of TM mode is found to be remarkably reduced after TE mode oscillates in the 7 µm-wide stripe mode stabilized laser. The dependence of threshold current, Ith, on the stripe width is examined experimentally and Ith is found to increase when the stripe width is decreased to less than about 10 µm. By taking mode loss into consideration, the increase in Ith with narrowing the stripe width is explained.

This paper proposes a method for calculating transfer function of transmission lines composed of combinations of multimode fibers with arbitrary index profiles. Bandwidths of graded-index fiber transmission lines are estimated taking into account optical equalization, mode conversion and deviation of index profiles from the power-law. Optical equalization greatly improves bandwidths for power-law fibers. As for those which deviate from power-law profile, perturbation of index profiles with low transversal spatial frequency significantly decreases the bandwidth of graded-index fibers. It is important to eliminate the low spatial frequency perturbation in index profiles to provide fibers with wide transmission bandwidths. Bandwidths of transmission lines are estimated when the phase of sinusoidal perturbation in the index profile varies randomly between the fibers at the sending and receiving ends. Calculations suggest that a 100 MHz bandwidth can be expected at a fiber length of 100 km, when deviation from the power-law profile is controlled to within 0.5% of relative index difference between the on-axis and cladding.

This correspondence is concerned with finding a set of pels for the prediction of NTSC signal when we are restricted to using a finite number of pels. The forward selection procedure and other methods are discussed, when they are applied to the intrafield prediction of the television signal.

A polarization-independent optical circulator for optical fiber communications is presented. It consists of a YIG Faraday rotator, a quartz half-wave plate and two pairs of rutile prisms. Insertion losses are 2.3 dB and isolations are 33 dB with fiber connection.

This paper considers a two-unit warm standby redundant system. Preventive maintenance (PM) for an active unit is scheduled after a certain period. When an active unit fails or undergoes PM while the other is in standby, the operation is switched to the standby unit. Probability of success in switchover is constant. If the system fails in switchover, the system stops the operation, and resumes it after a certain time. MTTFF, MTBF and steady state availability are obtained. Numerical examples show the effects of PM interval on them.

The effect of relative refractive index differences of single-mode fibers on zero-dispersion wavelength was investigated. Optimizing the fiber parameters, a single-mode fiber has been realized, which has minimum loss and minimum dispersion at the same wavelength in the 1.5 µm region.

Influence of high GeO2 concentration on the optical-loss in high numerical-aperture optical fibers has been investigated. It is shown that a large amount of OH ions are permanently trapped near Ge sites like near Si sites in binary GeO2-SiO2 glasses. The full Ge-OH absorption spectrum, including overtones, is very similar to the Si-OH spectrum but shifts to longer wavelength with increasing GeO2 concentration. Rayleigh scattering increases proportionally to GeO2 concentration and raises the transmission loss of the fibers, especially in shorter wavelength region. The minimum loss is, nevertheless, expected to be less than 1 dB/km even in the fibers containing GeO2 up to several tens of mol% because of a slight reduction of infrared absorption. The transmission loss of 0.8 dB/km at 1.55 µm was achieved by a 27 mol% GeO2-doped core fiber made by the VAD method.

This letter presents the connectivity number of 1-voxels in a 3-D digitized binary picture, and gives the necessary and sufficient condition that a 1-voxel in a 3-D picture is deletable. A shrinking algorithm for a 3-D object is suggested by using these results.

A new CCD linear image sensor with 2,048 elements has been developed by introducing photodiode processed by selective oxidation and ion implantation technologies. This construction provides high quantum efficiency at visible light with smooth spectral response, an output non-uniformity of1.5% and a dark current saturation time of 20 s. A transfer efficiency of 99.999% is achieved from a two-phase buried channel CCD. Transfer loss mechanism at a transfer gate was examined and the minimum aperture time of the gate proved to be as low as 1 µs. Spatial resolution of the device is superior to conventional sensors because of sharp sensitivity profile of the photoelement.

This paper presents a new method to calculate the asymptotic variances as a measure of accuracy in the estimation of rate constants of a compartmental system. Several numerical tests have been performed to analyze the effects of sampling conditions on the asymptotic variances. It is shown that there exists the optimal sampling interval which minimizes the asymptotic variances.

Making good use of low impedance and short wavelength characteristics of high dielectric substrate whose dielectric constant (εr) is 39 to 139, and advanced microwave integrated circuit (MIC) technology has been proposed to realize low-cost highly-reliable and small size UHF power amplifiers. Numerical calculation of single and parallel-coupled microstrip parameters on the high-dielectric constant substrate has been presented at first. Then the thick film technique application possibilities are discussed for high-dielectric substrate MICs, which is more suited for low price and mass production than conventional thin film technique. Based on theoretical and experimental estimation results, an amplifier with εr39 substrate has been developed to replace TWTs in television transposers, which provides a rated output peak power of 32 W with low distortion characteristics over the 650770 MHz frequency range. A compact 500 MHz-band 12 W class-C amplifier has also been developed successfully with use of εr139 substrate.

A method for designing two-dimensional FIR fan filters has been developed. With the proposed method, any size (i.e., even or odd) fan filter can be designed by extending a 1-D FIR prototype filter. This extension is performed by rotating and linearly interpolating the frequency response of the 1-D FIR prototype, and cascading an attenuator. The 2-D FIR fan filter obtained has specified number of fans and specified pass orientation. This has not been accomplished by conventional methods. The principle of the extension, examples of designing and the application in filtering are presented.

Traveling-wave light intensity modulator was constructed using the 5 µm wide strip optical waveguide of z-cut LiNbO3 and the asymmetric stripline as the modulator electrode. The half-wave voltage of 23 V and the extinction ratio of 97% were achieved. Modulation was performed up to 18 GHz.

System for the measurement of the respiratory response of human is introduced. This system has the facilities to supply the air which is mixed with CO2 or N2O. The subject inhales the gas of which contents variation can be controlled by the program. The system also measures the respiratory response of the subject which is caused by the changes of atmospheric circumstances, i.e., CO2 inhalation and records data. To check the concentration of agent gas according to the program, micro computer is used. Flow volume of expired gas, heart rate, concentration of supplied gas and that of expired gas are collected. One of the experiments in case of CO2 inhalation is shown. In this experiment the subject inhales the air which is mixed with CO2. Its pertition is 5% of the total volume.

This paper shows an improved rate equation by which the phase relation of the carriers and inhomogeneous property are taken into account for injection lasers. The direct modulation characteristics were analyzed as an application of this improved rate equation. A more general discussion was obtained for the resonance-like phenomenon and its suppression effect. For the undoped AlGaAs DH laser with index guiding structure, it is found that the resonance-like phenomenon is mainly suppressed by effect of spatial diffusion of injected carriers, reduction of the thresh-old level and lateral singlemode-operation. We also found that other mechanisms, such as mixing effect of the spontaneous emission, variation of longitudinal mode number and the intra-band relaxation, hardly affect to suppress the resonance-like phenomenon.