Hybrid electro-optic polymer/sol-gel waveguide directional coupler switches

Abstract

We report electro-optic (EO) switches using transversely tapered hybrid EO/sol-gel waveguide directional couplers. The length of the active region critically reduces to 1.5 mm with transverse tapers, which is shorter by a factor of 5 than the active region with vertical tapers. The transitions are performed from a sol-gel core to two EO polymer cores with gradual index changes using gray-scaled photobleaching. The device shows the lowest switching voltage and an active length product (VsLa) of 2.9 V cm with a guest–host EO polymer AJLS102, compared to hybrid waveguide switches and modulators with vertical taper and higher EO coefficients.