Low half-wave voltage and high electro-optic effect in hybrid polymer/sol-gel waveguide modulators

The authors report on hybrid electro-optic (EO) polymer-sol-gel modulators with low half-wave voltage (Vπ) and low insertion loss. Larger EO coefficient r33 results from the high poling field achieved when EO polymer is sandwiched between sol-gel cladding layers. The reduced interelectrode distance (d) resulting from the elimination of the sol-gel core layer in the active region further reduces Vπ. Straight channel phase modulators operate with Vπ =4.2 V at 1550 nm using a reduced d of 11.5 μm, which corresponds to an r33 of 78 pmV, among the highest r33 reported. The authors also examine a Mach-Zehnder modulator with Vπ =3.9 V using a conventional d of 15 μm.