Fluorinated polyimide waveguides were fabricated by CO<sub>2</sub> laser direct-writing. The poly(amic acid) micro-region
exposed by CO<sub>2</sub> laser beam was measured with FT-IR micro-spectroscopy. The FT-IR spectra indicated that the laser
imidized polyimide was semicrystalline, and the imidization degree of scanned micro-region increased with the rising of
output laser power. The increased aspect ratio of waveguide and smoothness of surface can be achieved by increasing the
pre-cured temperature (below 120 °C) and writing rate, and optimizing laser power and the distance between the lens
and the annular aperture. The guided light was clearly confined to the core of the fabricated waveguide, which means this technique can be used for fluorinated polyimide waveguide fabrication.