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We have succeeded in increasing size of InxGa1-xAs (x: 0.1-0.13) platy single crystals to 30 ×30 mm2 in surface area for mass production of laser diodes. Key points are to suppress convection in a melt and to keep constant temperature gradient for obtaining homogeneous crystals. Grown crystals have enough quality as substrates for 1.3 μm laser diodes. Fabricated laser diodes on these substrates were...
High-performance 1.3-μm InGaAlAs electroabsorption modulators integrated with DFB lasers are developed for long-reach 100-Gbit/s Ethernet system. Four-channel, 40-km SMF transmission at 25-Gbit/s operation is demonstrated for the first time.
Incident-power-dependent extinction ratio of electroabsorption modulators is shown and theoretically investigated by using microscopic theory combined with heat-flux calculation. The phenomenon stems from voltage-dependent temperature rise and the calculated results agree well with the experiment.
InP-based photonic integrated circuits are key devices for constructing photonic networks with low cost, low power consumption and small footprint. Many types of components are required to span various application areas, from backbone to on-chip.
This paper presents performance characteristics of a novel soft switching three phase utility frequency AC (UFAC) to high frequency AC (HFAC) direct converter with PFC function for industrial induction heating and melting applications. The proposed ??simple three phase system?? consists of single phase UFAC to HFAC direct converter in each phase, three phase low pass filter and IH load. This power...
Harmonic currents generated from the power electric equipment such as IH cooking heaters involve harmful influences to the other equipments connected to the utility grid. As for the IH cooking appliances, adding the PFC converter to the input stage of IH cooking heater is one of the practical solutions to suppress harmonic current influences. In this paper, two operation modes; DCM and CCM for the...
We report the first low threshold, ultra-small buried heterostructure photonic crystal laser. A very low threshold optical power of 1.5 muW in a butt-jointed InP waveguide and a maximum fiber output of 0.44 muW are achieved.
We aim to investigate biological function of emotional bodily movements while building a robot in the sense of survival. In this particular paper, we build a novel active vision system which detects weak signals by generating tremor actively. Proposed active vision system consists of a noise generator and a neural system. As a noise generator, we use motors with a decentered weight. And as a neural...
Questionnaires have been conducted to the owners of Paro in order to investigate people living with Paro at home. Although service robots such as AIBO have been commercialized and tend to be familiar with us, researches on owners' background are few. The owners of Paro answered the questionnaires and 85 feedbacks were obtained. The results showed that majority of the owners were females and have kept...
We demonstrate an all-optical wavelength-routing switch monolithically integrated with four wavelength converters and an 8times8 arrayed-waveguide-grating (AWG) filter. In the switch, double-ring-resonator-coupled tunable laser diodes allow rapid and stable switching between output ports (~5 ns) and optical gates based on a parallel amplifier structure prevent the input optical signal from being routed...
This paper describes an approach to improve the performance of the position sensorless control of an interior permanent magnet synchronous motor using parameter identification. The model-based sensorless method requires accurate motor parameters. At low speed, the resistance variation degrades the accuracy of position estimation. The identified parameter is used in the sensorless drive system to improve...
Deep trenches with inclined parts were fabricated with laser-induced backside wet etching by gradual shifting the irradiation area. Inclined parts with tilting angle of up to 30deg could be fabricated.
In recent decades, rapid progress in technology and changes in media environment have made it possible to convey works of art to the masses, even if it is hard to preserve the meaning of an original work of artpsilas conception. Such problems have occurred particularly with respect to several Asian nations whose works of art have a long history,since they cause concern among lovers of such artworks...
This paper proposes nondestructive current measurement for surface mounted power MOSFET on VRM board using the micro-magnetic probing technique to facilitation discussion of the self-turn-on phenomenon. A notable feature of the proposed technique is that the sensor part is much smaller than that of conventional methods because this method measures the intensity of a partial magnetic field caused by...
A long-term experiment of robot therapy for elderly people has been conducted at a health service facility for the aged since Aug. 2003. Three therapeutic seal robots, Paro, were introduced there. This paper describes the results of the experiment for five year. We regularly visited the facility twice or once a month and observed their interaction with the robots. Moreover, face scales that consist...
In this paper, a novel transient noise reduction technique for video conferencing system is proposed. Transient noise such as paper rustling noise of documents, prevents users of video conferencing systems from smooth conversation. To reduce transient noise, the proposed method utilizes vertically aligned multiple microphones. By spatial beamforming technique controlled by DOA (direction of arrival)...
We propose a novel non-stationary and convolutive noise reduction method under reverberant environments. Unlike many multichannel noise reduction methods, the proposed method does not need pre knowledge of impulse response or direction of arrival (DOA) of the target source. The proposed method is composed of two processes. On the noise reduction process, the noise component is reduced without the...
In this research, we developed a sphere-shaped mobile robot that can generate multiple behaviors by using only one motor. The robot can generate the translational motion and the rotational motion by controlling the motion of the motor. The motor itself acts as an eccentric weight during motions. To generate emergent behaviors, many protrusions are mounted on the surface of the spherical body. The...
A traveling-wave-electrode InP n-p-i-n Mach-Zehnder modulator monolithically integrated with a semiconductor optical amplifier was developed. Loss-less operation and full C-band 40-Gbit/s DPSK modulation with a low driving voltage of 3 Vpp was successfully demonstrated.
Using a frequency modulated DBR-LD and an optical filter, error-free transmission of a 40-Gb/s signal over a 0- to 20-km span (non-dispersion-shifted fiber) has been demonstrated for the first time.
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