Optical modulator having a plurality of modulator segments

1. A modulator apparatus comprising:

an optical path comprising an optical input port receiving an optical carrier wave, an optical output port outputting a modulated optical signal, and a succession of serially optically coupled optical modulator segments extending between the input and output optical ports modulating the optical carrier wave so as to obtain the modulated optical signal;

a plurality of segment drivers, wherein each segment driver has associated: a low voltage V low ; a high voltage V high ; a unique offset voltage V os ; and a threshold voltage V th ;

wherein each segment driver is electrically coupled to one of the succession of the modulator segments applies a driving voltage V d thereto in response to a control voltage V c , such that:

V d =V low when V c <V os −V th ;

V d =V high when V c >V os +V th ; and

V d varies between V low and V high when V c varies between V os −V th and V os +V th ;

an electrical input port receiving an electrical signal to be modulated onto the optical carrier wave to obtain the modulated optical signal;

a plurality of electrical connections between the electrical input port and each segment driver.

2. The modulator apparatus of claim 1 , wherein each segment driver comprises a limiting amplifier having the corresponding low voltage V low , the high voltage V high , the unique offset voltage V os , and the threshold voltage V th .

3. The modulator apparatus of claim 2 , wherein each electrical connection has a corresponding delay ΔT electrical between the electrical input port and each limiting amplifier; and wherein the delays ΔT electrical are such that in operation, the application of the driving voltage V d to individual optical modulator segments in the succession of optical modulator segments is substantially synchronized with propagation of the optical carrier wave therein.

4. The modulator apparatus of claim 1 , further comprising a comparator module operationally coupled to the electrical input port and the plurality of segment drivers to provide individual control signals to the plurality of segment drivers when the control voltage V c exceeds the offset voltages V os of corresponding segment drivers of the plurality of segment drivers.

5. The modulator apparatus of claim 1 , wherein the succession of serially optically coupled optical modulator segments comprises an optical waveguide and a succession of electrodes disposed along the optical waveguide and operationally coupled thereto.

6. The modulator apparatus of claim 1 , wherein the plurality of electrical connections comprise a succession of serially electrically coupled electrical delay line segments,

wherein each progressive one of the succession of electrical delay line segments is electrically coupled to a segment driver of the plurality of segment drivers, and

wherein the segment driver is electrically coupled to a corresponding progressive one of the succession of optical modulator segments.

7. The modulator apparatus of claim 6 , comprising more than eight optical modulator segments and more than eight segment drivers.

8. The modulator apparatus of claim 1 , wherein the offset voltage V os of each successive segment driver is greater than the offset voltage V os of the immediately preceding segment driver, if any.

9. The modulator apparatus of claim 8 , wherein the offset voltage V os of each successive segment driver is greater than the offset voltage V os of the immediately preceding segment driver, if any, by a same step voltage ΔV os .

10. The modulator apparatus of claim 1 , wherein a slope of each segment driver, defined as ( V high −V low)/ 2V th , is such that in operation, a degree of modulation of the modulated optical signal is substantially proportional to a magnitude of the electrical signal received at the electrical input port.

11. The modulator apparatus of claim 10 , wherein the slope is less than 5.

12. The modulator apparatus of claim 1 , wherein in operation, each segment driver has a delay ΔT amp between application of the control voltage V c thereto and generation of the corresponding driving voltage V d thereby, wherein the delays ΔT amp of at least two of the plurality of segment drivers are substantially different from one another.

13. The modulator apparatus of claim 1 , wherein at least one of the low voltage V low ,the high voltage V high , and the threshold voltage V.sub.th, of at least one segment driver of the plurality of segment drivers is substantially different from a corresponding one of the low voltage V low , the high voltage V high , and the threshold voltage V.sub.th of another segment driver of the plurality of segment drivers.

14. The modulator apparatus of claim 5 , further comprising a silicon photonic chip comprising the optical waveguide.

15. The modulator apparatus of claim 14 , wherein the silicon photonic chip comprises the plurality of segment drivers.

16. The modulator apparatus of claim 1 , wherein the low voltage V low , the high voltage V high , and the threshold voltage V th of each segment driver of the plurality of segment drivers are such that a degree of modulation of the modulated optical signal is a function of the electrical signal received by the electrical input port;

wherein the function is selected from the list consisting of quadratic, cubic, periodic, or an exponential function.

17. A method of modulating an optical carrier wave by an electrical signal, the method comprising:

propagating the optical carrier wave in a succession of serially optically coupled optical modulator segments; and coupling the electrical signal to a plurality of segment drivers,

wherein each segment driver has associated:

a low voltage V low ;

a high voltage high ;

a unique offset voltage V os ; and

a threshold voltage V th ,

wherein each segment driver is electrically coupled to one of the succession of the modulator segments for applying a driving voltage V d thereto in response to a control voltage V c , such that:

V d =V low when V c <V os −V th ;

V d =V high when V c >V os +V th ; and

V d varies between V low and V high when V c varies between V os −V th and V os +V th .

18. The method of claim 17 , wherein the electrical signal is coupled to an electrical input port, from which the electrical signal propagates to each segment driver via a plurality of electrical connections between an electrical input port and each segment driver; wherein each electrical connection has a corresponding delay ΔT electrical between the electrical input port and each segment driver; and wherein the delays ΔT electrical are such that the application of the driving voltage V d to individual optical modulator segments in the succession of optical modulator segments is substantially synchronized with propagation of the optical carrier wave therein.

19. The method of claim 17 , further comprising pre-selecting the offset voltage V os of each successive segment driver to be greater than the offset voltage V os of the immediately preceding segment driver, if any.

20. The method of claim 19 , further comprising pre-selecting the low voltage V low , the high voltage V high , the offset voltage V os , and the threshold voltage V th of each segment driver of the plurality of segment drivers such that V low of each successive segment driver is substantially equal to V high of the immediately preceding segment driver, if any.

21. The method of claim 19 , further comprising pre-selecting a slope of each segment driver, defined as (V high −V low )/2V th , so as to provide a degree of modulation of the optical carrier wave substantially proportional to a magnitude of the electrical signal received at the electrical input port.

22. A modulator apparatus comprising:

an optical path comprising an optical input port receiving an optical carrier wave, an optical output port outputting a modulated optical signal, and a plurality of serially optically coupled optical modulator segments extending between the input and output optical ports and modulating the optical carrier wave so as to obtain the modulated optical signal;

an electrical input port receiving an electrical signal to be modulated onto the optical carrier wave to obtain the modulated optical signal;

an analog to digital converter operationally coupled to the electrical input port, digitizing the electrical signal to provide a plurality of input digital signals;

a digital filter operationally coupled to the analog to digital converter, and receiving and digital filtering the plurality of input digital signals to provide a plurality of output digital signals, each of which for driving one of the plurality of optical modulator segments.

23. The modulator apparatus of claim 22 , wherein the digital filter is configured to provide an amplitude pre-emphasis to lessen a non-linearity of modulation of the optical carrier wave by the electrical signal.

24. The modulator apparatus of claim 22 , wherein the digital filter is configured to provide a pre-determined frequency response.

25. The modulator apparatus of claim 22 , further comprising

a photodetector optically coupled to the optical output port to provide a feedback signal; and

a controller operationally coupled to the photodetector and the digital filter to receive the feedback signal from the photodetector and provide a control signal to the digital filter in dependence on the feedback signal.