Optical modulator having coplanar electrodes for controlling chirp

An optical modulator, comprising:

• a substrate having an electrooptic effect;
• an optical waveguide having first and second cascading portions in the substrate, and transmitting an optical field;
• a first coplanar waveguide electrode having a first part over the second cascading portion and second and third parts extending beyond the second cascading portion, wherein the first part is approximately perpendicular to the second and third parts;
• a second coplanar waveguide electrode having a first part over the first cascading portion and second and third parts extending beyond the first cascading portion, wherein the first part is approximately perpendicular to the second and third parts;
• a third coplanar waveguide electrode having a shape symmetric to the first coplanar waveguide electrode and separated apart from the second coplanar waveguide electrode by a distance the same as the distance between the first and second coplanar waveguide electrodes;
• a fourth coplanar waveguide electrode having a shape symmetric to the first coplanar waveguide electrode, and having a first part over the second cascading portion and being in contact with the first part of the first coplanar waveguide electrode;
• a fifth coplanar waveguide electrode having a shape symmetric to the second coplanar waveguide electrode and separated apart from the fourth coplanar waveguide electrode by a distance the same as the distance between the first and second coplanar waveguide electrodes;
• a sixth coplanar waveguide electrode having a shape symmetric to the third coplanar waveguide electrode and separated apart from the fifth coplanar waveguide electrode by a distance the same as the distance between the second and third coplanar waveguide electrodes;
• and
• a voltage source supplying a voltage to the second and fifth coplanar waveguide electrodes, wherein the first, third, fourth, and sixth coplanar waveguide electrodes are grounded.