Masahiro Asano

Wide and fast wavelength-tunable mode-locked fiber laser using dispersion tuning

We demonstrate a wide and fast wavelength-tunable mode-locked fiber laser based on tuning the mode-locking frequency. The laser is in a sigma-laser configuration and a wideband semiconductor optical amplifier (SOA) at 1.3 μm wavelength region is used as a gain medium. Mode-locking is achieved by direct modulation of the injection current to the SOA, and a dispersion compensation fiber (DCF) is used to provide desired intracavity dispersion. By tuning the modulation frequency, a wide tuning range over 100 nm is achieved. Lasing wavelength is measured to be in linearly proportion to the RF frequency applied to the SOA. The sweep rate over the entire wavelength range (100 nm) can be raised to be as high as 100 kHz.

Design criteria of implantable blood pump in the goat’s chest cavity

It is desirable to use the adult goat as an experimental animal for the TAH with an implantable pneumatic driven blood pump since the calf has the problem of growth during the study period. Adult animals are also much more similar to adult human patients in physiological terms than immature animals such as the calf. However, it has not yet been possible to design a blood pump that fits well into the narrow space of the goat chest cavity. To solve this problem, a new design of the blood pump fitted to the goat chest cavity was investigated in this study. A bullet-shaped blood pump, which has two sack-type ventricles, was designed and fabricated together with a low-profile atrial cuff. The pump fitted well into goats weighing 47–67 kg and easily produced normal pump output. The results show the promise of future success in obtaining long survival with goats using this blood pump.

Widely and fast wavelength-tunable mode-locked fiber laser at 1.55μm region using intracavity dispersion

We realized a wavelength-tunable mode-locked fiber laser using intracavity dispersion. Continuous tuning over 100 nm was obtained at a sweep rate of 20 kHz. Discrete tuning was achieved over 39 nm by inserting a FFPI into the cavity.

Laser Angioplasty With Excimer Laser :Animal Experiment

Excimer laser is able to destruct tissue with less thermal effect. This characteristics was considered to prevent thermal perforation in laser angioplasty. In order to realize coronary laser angioplasty with excimer laser under the visual condition, the basic studies were performed to evaluate the tissue reactions of excimer laser on atheroma and to develop laser endoscopic system for the coronary arteries. The tissue reactions of excimer laser in atheroma were evaluated with rabbits atherosclerotic aorta, which was made with 1.5% high cholesterol diet. The bigger tissue destruction was obtained in accordance with the increase of the oscillating frequency. Excimer laser indused rather selective destruction of atheroma with high oscillating frequency. The fiber transmission of excimer laser was tried and atheroma was destructed through 400 μm core diameter fiber. Atheroma was observed as like as small lump under endoscopic obsevation, and excimer laser could be irradiated through the fiber under endoscopic view. In order to realize endoscopic application of excimer laser to the coronary arteries, the endoscope was designed from the point of percutaneous approach method to the coronary arteries, and 1.5 mm diameter of endoscope with the channel for laser fiber was developed experimentally. The endoscope could be inserted deeply into the coronary arteries of goat, and the laser irradiation could be performed under endoscopic observation. The possibility of visual coronary laser angioplasty with the combination of excimer laser and coronary endoscope was demonstrated with the endoscope.