Multi-parallel and serial optical digital to analog conversion

An optical digital to analog converter (oDAC), comprising:

• multiple optical paths that are parallel to each other;
• a combiner that comprises multiple combiner inputs and a combiner output;
• a splitter that is configured to receive an optical signal at a splitter input and split the optical signal between multiple splitter outputs to provide multiple path input signals to the multiple optical paths;
• wherein the multiple optical paths are formed between the multiple splitter outputs and the multiple combiner inputs;
• wherein the multiple optical paths are configured to optically process, in parallel, path input signals to provide path output signals;
• wherein each optical path is configured to apply an optical process that comprises applying optical modulation, by an optical gate of the optical path and under a control of an electrical digital-to-analog converter driver, to provide an optical signal having a value selected out of multiple constellation levels;
• wherein the multiple optical paths are configured to output multiple path output signals to the multiple combiner inputs;
• wherein the multiple optical paths comprise a first optical path and a second optical path;
• wherein the multiple path input signals comprise a first path input signal and a second path input signal;
• wherein an input optical power ratio between a power of the first path input signal and a power of the second path input signal differs from one;
• wherein the first optical path comprises a first modulator and a second modulator, the first modulator comprises a first segment that is followed by a second segment, the second modulator comprises a third segment that is followed by a fourth segment;
• wherein the first segment is driven by a first driver that comprises a first trans-impedance amplifier;
• wherein the second segment is driven by a third driver that comprises a third trans-impedance amplifier;
• wherein the third segment is driven by a second driver that comprises a second trans-impedance amplifier;
• wherein the fourth segment is driven by a fourth driver that comprises a fourth trans-impedance amplifier;
• wherein a first modulator phase shift ratio between a phase shift introduced by the first segment to a phase shift introduced by the second segment substantially equals 1.552;
• wherein a second modulator phase shift ratio between a phase shift introduced by the third segment to a phase shift introduced by the fourth segment ranges between 1.1 and 1.95.

A method for optical digital to analog conversion, the method comprises:

• splitting, by a combiner, an input optical signal to multiple path input signals;
• optically processing, the multiple path input signals, by the multiple optical paths, in parallel to provide path output signals;
• wherein the optically processing comprises applying optical modulation by optical gates of the multiple optical paths and while driven by multiple electrical modulators, to provide optical signals;
• and
• combining, by a combiner, multiple path output signals that are outputted from the multiple optical paths to provide an oDAC output signal having a value selected out of values of a single quadrature constellation;
• and
• wherein the multiple optical paths comprise a first optical path and a second optical path;
• wherein the multiple path input signals comprise a first path input signal and a second path input signal;
• wherein the input optical power ratio between the power of the first path input signal and the power of the second path input signal differs from one;
• wherein the first optical path comprises a first modulator that is driven by a first driver that comprises a first trans-impedance amplifier that has a first trans-impedance value and the method comprises receiving by the first trans-impedance amplifier a first input current that exhibits a first peak input current value;
• wherein the second optical path comprises a second modulator that is driven by a second driver that has a second trans-impedance amplifier that has a second trans-impedance value and the method comprises receiving by the second trans-impedance amplifier, a second input current that exhibits a second peak input current value;
• and
• wherein the trans-impedance ratio between the first trans-impedance value and the second trans-impedance value is configured to compensate for the ratio between the first peak input current value and the second peak input current value.