Electro-optic polymer/TiO2 vertical slot waveguide modulators

We report the efficient poling for efficient poling of electro-optic (EO) polymer in a hybrid EO polymer/TiO₂ vertical slot waveguide modulators based on enhanced conductivity of sol-gel silica under-cladding. The electrical volume conductivity of sol-gel silica cladding increases approximately 30 times when the calcining time of the cladding layer is critically reduced to 45 minutes, which increases the in-device EO coefficient of the 600-nm-thick EO polymer film in modulators and reduces the lower half-wave voltage (V) of the modulators. The lowest driving voltage (V_π) of the TiO₂ slot waveguide modulator is 2.0 V for an electrode length (L_e) of 10 mm and wavelength of 1550 nm (V_πL_e = 2.0 V-cm) for the low-index guest-host EO polymer SEO125. The optical propagation loss is reduced to 7 dB/cm.