Development for medical surgical system with function variability and flexible delivery using dual-wavelength infrared fiber laser

We developed a medical surgical system with function variability and flexible delivery of dual-wavelength infrared fiber laser that simultaneously oscillated 3 and 2 μ m radiation. We studied the function variability (cutting/coagulation) of this fiber laser using a specially designed filter which contained two adjacent areas with different transmission for 2 μ m radiation. When the power of 3μ m radiation was set to 0.6 W and the power of 2 μ m radiation was changed from 0 W to 0.77 W using this filter at the beam traveling speed of 0.25 mm/s, the cutting groove formed in myocardium tissue increased from 0.80 mm to 0.89 mm and the coagulation layer thickness increased from 0.41 mm to 0.85 mm. We successfully developed a filter system that could continuously control coagulation layer thickness with cutting capability constant. We studied a flexible beam delivery using a single crystal sapphire fiber. The transmission efficiency per meter for 3 and 2 μ m radiation using a 200-μ m core-diameter sapphire fiber was 58.0 % and 60.4 %, respectively. The bending loss at 3-cm loop radius was 5.6 %. The high flexibility and low bending loss of the sapphire fiber might make it possible to apply the dualwavelength infrared fiber laser to endoscopic treatment. In summary, these results may encourage the possibility for practical use of the fiber laser.