Development of a Lens-less Mid-infrared Laser Head for the Optical Fiber Tip Oscillation to Apply to Therapeutic Treatment

Abstract

Mid-infrared lasers having the wavelength of the vicinity of 3µm are considered as effective for treatment of biomedical tissue because of the strong absorption to water. The drawback of 3µm laser is the difficulty to propagate the silica optical fiber. We have reported the optical fiber tip oscillation laser that has a Er,Cr:YAGG laser crystal and coupling lenses on the tip of a silica fiber outputs 2.8µm laser pumped by laser diode (LD). In this paper, we demonstrated a lens-less laser head for the optical fiber tip oscillation. By using the silica optical fiber having a core diameter of 105µm and a numerical aperture (NA) of 0.12, the average output power of 1.0W was achieved from the lens-less laser head during a squire wave modulation for suppressing heat generation.