Lasers, waveguides and fibers for 3.0-μm medical applications

In the last few years, there has been an increasing interest for the 3.0 micrometers laser radiation, as this wavelength is very strongly absorbed by the water and the other components of soft and hard tissue, in various medical applications, as soft tissue treatment, atherosclerotic plagues removal, treatment of eye lenses, vitreous surgery, hard tissue treatment, bone cutting and drilling, dentistry applications, etc. For all these medical applications reliable lasers emitting in the 3.0 micrometers wavelength range are needed and thus an intensive development effort is going on throughout the world. Our laser development effort, with the Er:YAG and the HF lasers, the only lasers emitting in the 3.0 micrometers wavelength part of the spectrum, in N.T.U.A., is briefly described in this article. For each one of the above possible medical applications, a demand for good flexible delivery systems, for pulsed Er:YAG or continuous wave and pulsed HF laser radiation arises. Several research groups around the world have suggested some possible solutions and among them are sapphire fibers, zirconium fluoride glasses, hollow metallic waveguides, hollow dielectric waveguides, hollow plastic waveguides, etc. In this paper we present the transmission properties of dielectric coated silver hollow glass waveguides fabricated in Japan, dielectric coated quartz waveguides and hollow plastic waveguides fabricated in Israel, sapphire fibers fabricated in USA, and fluoride glass fibers fabricated in France, we compare their straight and bent loss characteristics and we discuss their potential in the above mentioned medical applications.