Self-fabricated single mode waveguide in fluoride glass excited by self-channeled plasma filaments

Abstract

Self-fabricated permanent structure of single mode waveguide in optical fluoride glasses was demonstrated using the self-channeled plasma filament excited by a femtosecond (130fs) Ti:sapphire laser (λp=790nm). The photoinduced refractive index modification in ZrF4–BaF2–LaF3–AlF3–NaF glasses reached a length of approximately 10–15mm from the input surface of the optical glass with the diameters ranging from 5to8μm at the input intensities of more than 1.0×1012W∕cm2. The graded refractive index profiles were fabricated to be a symmetric form from the center of optical fluoride glass, and a maximum value of refractive index change (Δn) was measured to be 1.3×10−2. The beam profile of the output beam transmitted through the modified region showed that the photoinduced refractive index modification produced a permanent structure of single mode waveguide.