Multi-branch microwave line for electro-optical devices

An electro-optical device for controlling an optical signal in response to an electrical signal comprising:

• a substrate having an optical path therethrough, said optical path having an input section and an output section and having an intermediate section between said input and output sections, said intermediate section having first and second arms that diverge at an end of said input section and that converge at an end of said output section, said first and second arms having substantially opposite poling polarities;
• an electrical path along said substrate, said electrical path having input and output signal lines, said electrical path having first and second branches between said input and output signal lines for conducting a signal in electrical parallel relationship from said input line to said output line, said first branch being aligned with said first arm to apply an electric field to said first arm, said second branch being aligned with said second arm to apply an electric field to said second arm, said electrical path having a first microwave impedance;
• and
• source means connected to said input signal line for applying a microwave signal to said first and second branches, said source means having a microwave impedance substantially matched to said first microwave impedance.

A method of forming an electro-optical device comprising steps of:

• forming a substrate having at least one polymeric layer and an optical path within said polymeric layer, including defining said optical path to have input and output sections and an intermediate section between said input and output sections, said defining said optical path including changing the index of refraction of said polymeric layer at selected regions of said polymeric layer and further including forming said intermediate section to have first and second arms that diverge at an end of said input section and converge at an end of said output section;
• establishing a nonlinear electro-optic effect at each of said first and second arms, including poling said polymeric layer such that opposite poling polarities are formed at said first and second arms;
• forming an electrical path along said substrate such that an input line having a first electrical impedance is connected to first and second branches, including aligning said first and second branches to couple substantially identical electrical fields respectively to said first and second arms;
• and
• connecting a microwave signal to said electrical path to induce said substantially identical electrical fields.