Both wavelength dispersion and a dispersion slope of a line fiber are simultaneously compensated for by combining two types of dispersion compensators having different characteristics. The implant body has a tapered cylindrical surface near its top end and an internally threaded or unthreaded passage extending into the implant body through an opening at the top of the implant. The second clad layer has a dielectric permittivity larger than that of the first clad layer, and the second clad layer has a thickness thicker than that of the first clad layer. The ozone is supplied and discharged from the same opening. The needle fixing body is mold processed of resin to be made a slightly longer than the tray ditch so that each projection part of the waveform adheres closely onto the tray, to increase the force to hold and fix the needles.