Inductivity coupled plasma etching to fabricate the nonlinear optical polymer photonic crystal waveguides

To fabricate the photonic crystal (PC) waveguides with large nonlinearity, the inductivity coupled plasma etching characteristics are systematically investigated for the nonlinear optical (NLO) polymer and the fabrication techniques for the NLO polymer PC waveguides are established at the suboptical wavelength scale. We demonstrate the successful fabrication of the NLO polymer PC waveguides with circular holes of diameter 120 nm and very straight sidewalls by using this technique. Moreover, by the examination of the pattern size dependence of etch rates, it is found that rapid reduction of etch rate due to the microloading effect is prevented in the circular hole sizes up to 100 nm at the optimized polymer etching condition. The sharp dip structures originating from resonance coupling to the photonic crystal waveguide modes are clearly observed in the optical reflectance spectra, which exhibits the high-precision feature of this waveguide and the good processability for the material in this technique.