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High-efficiency coupling of stacked multifiber tapes to a vertical-cavity surface-emitting laser (VCSEL) array is demonstrated. Three fiber tapes, each of which includes four multimode fibers, are coupled to a 4 ×3 VCSEL array simply by inserting fibers into guiding holes fabricated on the back side of the substrate. Mirrorlike smooth floors of the holes are formed by electron cyclotron resonance reactive ion beam etching, which results in great improvement of coupling efficiency. The average measured coupling efficiency is 81.3%.

A novel structure of a vertical-cavity surface-emitting laser (VCSEL) was proposed and demonstrated. Using a common-anode configuration, lower mesa height and lower electrical resistance were realized. The threshold current was 6 mA for a 10-µm-diameter device under room-temperature pulsed operation. The lasing wavelength was 939 nm. This configuration is suitable for large-scale integration. We also propose an optoelectronic integrated circuit (OEIC) with the common-anode configuration, which consists of a VCSEL and a heterostructure phototransistor (HPT) for optical parallel processing.

Solenoid has been widely used as a highly reliable and short stroke actuator. However, the main defects are the delay of the actuator motion and its low driving efficiency. Analyzing the various driving parameters, three major factors of solenoid delay are found: mechanical delay caused by movable inertia, current delay by solenoid inductance, and magnetic flux delay by eddy-current. This paper introduces two improvement methods: a driving circuit which utilizes the constant current of a choke coil to make the solenoid current response faster, and a ferrite core which is widely used as a radio frequency magnetic material to decrease the eddy-current loss. These ideas reduce both current delay and magnetic flux delay and also improve the driving efficiency of the actuator. The resulting motion indicates a very small dead time, which is considered very good for servoactuator. High speed solenoid actuator is applied to develop a direct-drive servo-valve and a linear hydraulic servo system. A lthought here is room for improvementt, h e results indicatet he capability of this solenoid actuator to the highly efficient servo system.

One of the biggest problems of realizing the fast motion of a robot manipulator is its dynamic reflection. The driving torque calculated from the mathematical model well compensates for this reflection. However, the dynamic property changes according to the clamped load and arm position. This paper introduces a high-speed adaptive control technique using identification. First, the manipulator is controlled only by a planned trajectory. A time domain identification is then applied to estimate the robot dynamics. The inverse transfer function is used to calculate the actuating signal which produces the high-speed motion of the next cycle. The proposed technique is applied to 3-dimensional positioning of a multijoint manipulator.

We have been developing InGaAs/InP monolithic PIN/Amplifiers. This paper describes the consideration to use self-aligned FETs with a view to improving the operating speed. To this end, the device structure and the fabrication process have first been discussed for integrating the self-aligned JFETs and photodiodes. Next, photodiodes and FETs of this configuration have been fabricated and their characteristics evaluated. It was found that the dark current of the photodiode could be reduced to 2.7 nA at −3 V and that the cutoff frequency of the FET was improved to be 3.0 GHz. Finally, a monolithic PIN/Amplifier was fabricated. Presently, the frequency characteristics of fabricated PIN/Amplifiers are not so good. This is believed to be caused by the fact that the gate electrode of the FET is a Schottky electrode. If this problem is settled in the future, a PIN/Amplifier with a 3-dB bandwidth of about 700 MHz can be realized.

Carbon-14 kinetic isotope effects (k12⁄k14) were determined for the solvolysis of phenethyl (1a) and 2-(p-methoxyphenyl)ethyl (1b) p-nitrobenzenesulfonates in acetic, formic, and trifluoroacetic acids. Phenyl-1 carbon effects were all in the range of 1.02–1.04 except for the acetolysis of 1a (k12⁄k14=1.005), which has been proved to proceed mainly via the aryl unassisted (ks) pathway. In all other reactions, which proceed mainly via the aryl assisted (kΔ) pathway, the phenyl-1 carbon apparently changes its bonding in the transition states. A large α-carbon effect (1.131) and a small β-carbon effect (1.013) as well as a medium phenyl-1 effect (1.022) were observed for the formolysis of 1b, whose mechanism is thought to be exclusive kΔ without troublesome ion-pair return. These observations, together with α- and β-deuterium effects reported already, enabled us to describe the qualitative nature of the bridged transition-state structure of the kΔ pathway, i.e., advanced Cα–O bond rupture, slight Cα–CPh−1 bon...

A PIN/JFET using an InP-based material for receiving an optical signal at a wavelength of 1 μm has been developed. From a practical viewpoint, operation using a single power supply is desirable. In this study, an opto-electric integrated circuit (OEIC) composed of a PIN/PD, JFET, feedback resistor, etc., was fabricated on a semi-insulating substrate and then the characteristics of each component were evaluated. The pinchoff voltage and cutoff frequency of the JFET were 1.2 V and 900 MHz, respectively. The transimpedance in operation was 965 ft, which was almost the same as the feedback resistance. When the power supply voltage was 5 V, the 3-dB cutoff frequency was 220 MHz, indicating that operation using a single power supply is feasible. The 1/f noise of JFET was 20 nV √Hz and the receiver sensitivity was −24.1 dBm. High reliability could be ensured by employing a 50-hr THB screening test.