High performance optical modulators and drivers

An optical modulator, comprising:

• a first waveguide;
• a second waveguide, each of the first waveguide and the second waveguide being formed from a thin film including at least one of lithium niobate or lithium tantalate, the thin film having a thickness of not more than two micrometers;
• a first differential electrode pair having a first pair negative electrode and a first pair positive electrode arranged on opposing sides of the first waveguide, the first pair negative electrode being arranged on a distal side of the first waveguide relative to the second waveguide and the first pair positive electrode being arranged on a proximal side of the first waveguide relative to the second waveguide;
• a second differential electrode pair having a second pair negative electrode and a second pair positive electrode arranged on opposing sides of the second waveguide, wherein the second pair negative electrode is arranged on a distal side of the second waveguide relative to the first waveguide and the second pair positive electrode is arranged on a proximal side of the second waveguide relative to the first waveguide;
• a first line coupled to the first pair negative electrode and to the second pair negative electrode, the first line being connectable to an output of a differential driver;
• a second line coupled to the first pair positive electrode and to the second pair positive electrode, the second line being connectable to another output of the differential driver;
• and
• wherein the first waveguide and the first differential electrode pair in combination with the second waveguide and the second differential electrode pair provide optical modulation for a frequency bandwidth of 50-100 GHZ;
• wherein the first waveguide, the second waveguide, the first differential electrode pair and the second differential electrode pair are on a substrate structure including a substrate and an underlayer on the substrate, the substrate having a substrate microwave dielectric constant, the underlayer having an underlayer dielectric constant less than the substrate microwave dielectric constant such that the substate structure has a total microwave dielectric constant less than eleven in a region of a microwave mode for each electrode of the first differential electrode pair and the second differential electrode pair;
• wherein the first pair negative electrode and the second pair negative electrode and the first pair positive electrode and the second pair positive line have a first impedance difference;
• and
• wherein the first line and the second line have a second impedance difference configured to compensate for the first impedance difference.

A method, comprising:

• receiving an optical signal at an optical input of an optical modulator, the optical input directing the optical signal to a first waveguide and a second waveguide, each of the first waveguide and the second waveguide being formed from a thin film of at least one of lithium niobate or lithium tantalate, the thin film having a thickness of not more than two micrometers;
• receiving a differential signal at an interface of the optical modulator, the differential signal including a positive signal and at least one negative signal;
• transmitting the differential signal to a first differential electrode pair and a second differential electrode pair, the first differential electrode pair having a first pair negative electrode and a first pair positive electrode arranged on opposing sides of the first waveguide, the first pair negative electrode being arranged on a distal side of the first waveguide relative to the second waveguide and the first pair positive electrode being arranged on a proximal side of the first waveguide relative to the second waveguide, the second differential electrode pair having a second pair negative electrode and a second pair positive electrode arranged on opposing sides of the second waveguide, wherein the second pair negative electrode is arranged on a distal side of the second waveguide relative to the first waveguide and the second pair positive electrode is arranged on a proximal side of the second waveguide relative to the first waveguide, a first line being coupled to the first pair negative electrode and to the second pair negative electrode, the first line being connectable to an output of a differential driver, a second line being coupled to the first pair positive electrode and to the second pair positive electrode, the second line being connectable to another output of the differential driver;
• the transmitting further including
• providing the positive signal to the first pair positive electrode and to the second pair positive electrode, the providing the positive signal further including converting the positive signal into a first positive signal for the first pair positive electrode a second positive signal for the second pair positive electrode;
• and
• providing the at least one negative signal to the first pair negative electrode and to the second pair negative electrode;
• wherein the first waveguide and the first differential electrode pair in combination with the second waveguide and the second differential electrode pair provide optical modulation for a frequency bandwidth of 50-100 GHZ;
• wherein the first waveguide, the second waveguide, the first differential electrode pair and the second differential electrode pair are on a substrate structure including a substrate and an underlayer on the substrate, the substrate having a substrate microwave dielectric constant, the underlayer having an underlayer dielectric constant less than the substrate microwave dielectric constant such that the substate structure has a total microwave dielectric constant less than eleven in a region of a microwave mode for each electrode of the first differential electrode pair and the second differential electrode pair;
• wherein the first pair negative electrode and the second pair negative electrode and the first pair positive electrode and the second pair positive electrode have a first impedance difference;
• and
• wherein the first line and the second line have a second impedance difference configured to compensate for the first impedance difference.

An interface to an optical modulator, comprising:

• a first differential line pair having a first differential line pair negative line and a first differential line pair positive line arranged on opposing sides of a first waveguide, wherein the first differential line pair negative line is arranged on a distal side of the first waveguide relative to a second waveguide and the first differential line pair positive line is arranged on a proximal side of the first waveguide relative to the second waveguide, wherein each of the first waveguide and the second waveguide is formed from a thin film of at least one of lithium niobate or lithium tantalate, the thin film having a thickness of not more than two micrometers;
• and
• a second differential line pair having a second differential line pair negative line and a second differential line pair positive line arranged on opposing sides of the second waveguide, wherein the second differential line pair negative line is arranged on a distal side of the second waveguide relative to the first waveguide and the second differential line pair positive line is arranged on a proximal side of the second waveguide relative to the first waveguide, the first waveguide and the first differential line pair in combination with the second waveguide and the second differential line pair provide optical modulation for a frequency bandwidth of 50-100 GHZ;
• a first line coupled to the first differential line pair negative line and to the second differential line pair negative line, the first line being connectable to an output of a differential driver;
• and
• a converter configured to convert a positive input line to the first differential line pair positive line and the second differential line pair positive line, such that a positive signal provided to the interface by the positive input line is converted into a first positive signal for the first differential line pair positive line and a second positive signal for the second differential line pair positive line, the converter including a second line coupled to the first differential line pair positive line and to the second differential line pair positive line, the second line being connectable to another output of the differential driver;
• wherein the first differential line pair negative line and the second differential line pair negative line and the first differential line pair positive line and the second differential line pair positive line have a first impedance difference and
• wherein the first line and the second line have a second impedance difference configured to compensate for the first impedance difference.