Ryuji Kobayashi

1.3-/spl mu/m AlGaInAs strain compensated MQW-buried-heterostructure lasers for uncooled 10-gb/s operation

We have successfully fabricated 1.3-/spl mu/m AlGaInAs strain-compensated multiple-quantum-well (MQW) buried-heterostructure (BH) lasers by narrow-stripe selective metalorganic vapor-phase epitaxy. Based on the optimization of AlGaInAs strain compensated MQW and the Al-oxidation-free BH process, we obtained a low-threshold current of 12.5 mA and a relaxation frequency of more than 10 GHz at 85/spl deg/C for Fabry-Perot lasers. For distributed feedback lasers, we demonstrated a 10-Gb/s operation and transmission of over 16 Km for a single mode fiber at 100/spl deg/C. Furthermore, a record-low 25.8-mA/sub p-p/ modulation current for a 10-Gb/s modulation at 100/spl deg/C was demonstrated with shorter cavity and high grating-coupling coefficient. A median life of more than 1/spl times/10/sup 5/ h at 85/spl deg/C was estimated after an aging test of over 5000 h for these lasers. These superior characteristics at high temperatures were achieved by the combination of the high differential gain of AlGaInAs strain compensated MQW and the BH structure.

10-Gb/s 23-km penalty-free operation of 1310-nm uncooled EML with semi-insulating BH structure

We have developed a 1310-nm uncooled electroabsorption modulator integrated light source (EML) with an AlGaInAs multiple quantum well (MQW) active/absorption stripe, which was simultaneously grown using the narrow-stripe selective MOVPE technique and was buried with an Fe-doped InP. The Al-content MQW oxidation was effectively inhibited by using the same technique. An experiment-based evaluation of the devices performance revealed that by only changing the modulation bias voltage linearly with temperature, it was possible to achieve 10-Gb/s penalty-free operation at up to 85/spl deg/C over a 23-km single-mode fiber.

Low Drive-Current and Wide Temperature Operation of 1.3-μm AlGaInAs-MQW BH-DFB Lasers by Laterally Enhanced Cladding Layer Growth

Low drive-current and extremely wide temperature (from -45 to 105°C) operation were demonstrated in 10-Gb/s directly-modulated 1.3-μm AlGalnAs-MQW BH-DFB lasers with a new DH structure having a p-InP cladding layer grown by a lateral-growth technique.

The Effect of Low Calcium Diet on Bone in Ovariectomized Mice

This study investigates the effects of Ca on bone in the ovariectomized mice. Twenty-six female ICR mice aged 5 weeks were used. They were ovariectomized (OVX) or sham-operated (SHAM) and fed standard mouse diet (SF) or special low calcium diet (L.Ca), respectively. All animals were sacrificed at day 100 after operation. Mechanical strength of the left femur and tibia was measured by the three-point bending strength test. The bones were dried, weighed and burned to ash. Correlation between mechanical strength and ash content was found. A specimen of the right tibia was prepared. Mechanical strength, ash content and ratio of dry bone weight to body weight of the femur and tibia in OVX and L.Ca mice were significantly less than in SHAM and SF mice. SHAM/SF mice and OVX/L.Ca group showed highest and lowest values in all cases. The values for the femur and tibia in OVX/SF mice were lower than in SHAM/SF group and in OVX/L.Ca group were less than in OVX/SF mice. Correlation coefficients for mechanical strength and ash content were 0.704 and 0.776 for the femur and tibia. Ca is thus related to inhibition of bone loss and maintenance of bone mass and effective prevention of osteoporosis.

Modification of postural response caused by footwear conditions.

The purpose of this study was to clarify the effect of changing footwear conditions on postural response against postural perturbation. Twenty-three healthy subjects participated in this study. Postural response was induced by moving a platform forward, hereafter referred to as forward-perturbation of a platform. The center of pressure (COP) from the force plate and the electromyograms (EMG) of the tibialis anterior (TA) and quadriceps femoris (QUAD), which are both agonists of the response, were measured. The effect of plantar material and shape of footwear on postural response was examined as footwear condition. Changing plantar materials had an effect on integrated EMG of the agonists (IEMG) but not on the response pattern. On the other hand, the shape of footwear had an effect on the response pattern but not on IEMG. It was supposed from this result that changes in somatosensory input, caused by coupling of plantar material and shape of footwear, modifies postural response variously.

10 Gbit/s FP-TOSA and PIN-ROSA for 10GBASE-LRM application

Wide temperature operating 10 Gbit/s 1.3 /spl mu/m AlGaInAs FP-TOSA and InGaAs PIN-ROSA were newly developed for 10GBASE-LRM application. Error-free 330 m MMF transmission was successfully demonstrated using these components and EDC for the first time.

100ºC, 10-Gb/s Direct Modulation with a Low Operation Current of 1.3-?m AlGaInAs Buried Heterostructure DFB Laser Diodes

1.3-?m AlGaInAs BH DFB laser diodes have been developed for the first time. 100°C, 10-Gb/s operation and transmission over 16 km of SMF were demonstrated with an 80-mA operating current and a 42-mAp-p modulation current.

Time course of influence by ovariectomy and calcium diet on bone properties in mice.

This study was investigated the influence by ovariectomy (OVX) and calcium diet on bone properties in eighty-one female ICR strain mice with age of 5 weeks. The animals were randomly assigned to sham operation (SHAM), OVX, SHAM+low Ca intake (L.Ca) and OVX+L.Ca group. They were euthanized with lethal dose of pentobarbital sodium at day 50, 100 and 140 post-operatively. For determining the bone properties, both femur and tibial bones were excised from the hind limb, and removed off surrounding tissues. Thereafter, bone length, bone dry weight, and also mechanical strength and ash content of the bones were determined. The bone length on both femur and tibia was significantly longer in OVX group than in the other groups after 50 day of experiment, this situation was continued to the end of the experiment. Bone dry weight, mechanical strength, and ash content were significantly decreased by OVX and L.Ca over the time of the experiment, and those of OVX+L.Ca group were the lowest in all groups. OVX and L.Ca have a great potential for weakening the mechanical strength and have an additive effect when combined. OVX and L.Ca block the gain of bone mass.