Single-mode polymer waveguide modulator

We report herein the first single-mode polymer waveguide modulator which can be formed on any surface regardless of its conductivity and refractive index. These include semiconductor, conductor, and insulator surfaces. The tunability of the refractive index of the polymer film allows us to shift the guiding layer from a stepped index profile to a graded index profile. The phase-matching condition for optical power transfer is achieved through current-induced index modulation. Thirty-six dB extinction ratio, which includes 3 dB absorption loss and 33 dB phase-matched cross coupling, was observed with a current injection density of ∼1.8 μA/μm2. Unlike the conventional symmetrical dual channel coupler, the disparity of the collinear waveguide pair provides us with a much larger dynamic range of waveguide dimension suitable for generating the required phase-matching condition and thus easing the requirement of waveguide fabrication.