Integrated low-voltage CMOS-compatible electro-optic modulator

1. A method of modulating an optical signal, comprising:

receiving an unmodulated optical signal input to a slot waveguide having:

a slot in a direction of propagation of the unmodulated optical signal, the slot being filled at least partially with an electro-optic polymer poled orthogonal to the direction of propagation, and

Bragg gratings defined along sides of the slot to slow the optical signal;

modulating a phase of the unmodulated optical signal by providing an electrical input signal to the slot waveguide via a pair of electrodes; and

outputting a modulated optical signal with the modulated phase.

2. The method of claim 1 , further comprising:

splitting the unmodulated optical signal prior to the slot waveguide into a first optical signal and a second optical signal, wherein the first optical signal is modulated by the electrical input signal;

passing the second optical signal through an additional slot waveguide; and

combining the modulated first optical signal and the second optical signal to form the modulated optical signal.

3. The method of claim 2 , wherein the second optical signal is modulated by an additional electrical input signal prior to the combining step.

4. The method of claim 3 , wherein the modulating includes delaying the phase of the first optical signal and/or advancing the phase of the second optical signal.

5. The method of claim 2 , wherein the second optical signal is passed unmodulated through the additional slot waveguide prior to the combining step.

6. The method of claim 1 , wherein the electrical input signal is a voltage signal and the modulation is carried out by applying the voltage signal to a pair of electrodes adjacent to the slot waveguide.

7. An electro-optic modulator for modulating an unmodulated optical signal, the electro-optic modulator comprising:

a slot waveguide configured to propagate an optical signal, the slot waveguide including a slot and Bragg gratings defined by outer walls of the slot, the Bragg gratings configured to slow the optical signal; and

a pair of electrodes extending parallel and adjacent to the slot waveguide, electrodes in the pair configured to carry an electrical modulation signal to induce a change in a phase of the optical signal,

wherein the slot of the slot waveguide is at least partially filled with an electro-optic polymer poled in a direction orthogonal to a direction of propagation of the optical signal in the slot waveguide.

8. The electro-optic modulator of claim 7 , wherein the Bragg gratings are periodic structures whose widths are modulated by recessed and protruding portions.

9. The electro-optic modulator of claim 7 , wherein the slot having the electro-optic polymeric material defines a low refractive index region, and the Bragg gratings formed on the outer walls of the slot define a high refractive index region.

10. The electro-optic modulator of claim 7 , wherein the slot is filled with a non-polymeric electro-optic material.

11. An integrated photonic circuit comprising the electro-optic modulator of claim 7 .

12. The electro-optic modulator of claim 7 , wherein the electro-optic modulator is fabricated by a CMOS-compatible silicon photonic fabrication technique.

13. The electro-optic modulator of claim 7 , further comprising:

an optical splitting element configured to split the unmodulated optical signal into a first optical signal and a second optical signal, the first optical signal being propagated through the slot waveguide;

an additional slot waveguide configured to propagate the second optical signal; and

an optical combining element configured to combine the first optical signal and the second optical signal to form a modulated optical signal.

14. The electro-optic modulator of claim 13 , wherein the additional slot waveguide includes:

an additional slot and additional Bragg gratings disposed on both outer walls of the additional slot, the additional Bragg gratings configured to slow the second optical signal; and

an additional pair of electrodes extending parallel and adjacent to the additional slot waveguide.

15. The electro-optic modulator of claim 14 , wherein electrodes in the additional pair are configured to carry another electrical modulation signal to induce a change in the phase of the second optical signal.

16. The electro-optic modulator of claim 15 , wherein the electrical modulation signal in the additional pair of electrodes is a polarity reversed signal of the first pair of electrodes.

17. The electro-optic modulator of claim 13 , wherein the second optical signal is unmodulated prior to being combined with the first optical signal at the optical combining element.

18. The electro-optic modulator of claim 11 , wherein the electro-optic modulator is a Mach-Zehnder interferometer type modulator.

19. The electro-optic modulator of claim 7 , wherein the electro-optic modulator has at least one of the following attributes:

a half-wave voltage V π less than 1 V,

an insertion loss less than 5 dB, and

a bandwidth of at least 100 GHz.

20. A slot waveguide for electro-optic modulation, comprising:

a slot and Bragg gratings defined by outer walls of the slot, the Bragg gratings configured to slow an optical signal, the slot defining a low-refractive index region and the Bragg gratings spaced apart by the slot defining a high-refractive index region; and

a pair of electrodes extending parallel and adjacent to the slot waveguide, the electrodes configured to carry an electrical modulation signal to induce a change in a phase of the optical signal,

wherein the slot of the slot waveguide is at least partially filled with an electro-optic polymeric material poled in a direction orthogonal to a direction of propagation of the optical signal in the slot waveguide.