1. A method of recovering a clock signal and a data signal of a digital data stream, the method comprising:
sampling said digital data stream to generate a sampled data signal;
sampling said digital data stream to generate a data edge clock signal aligned with edge transitions of the digital data stream;
generating a phase difference signal corresponding to the phase difference between the sampled data signal and the data edge clock signal;
generating, by a loop filter, a phase adjustment signal based on the phase difference signal;
adjusting the bandwidth of the loop filter based on predetermined operating modes;
and
generating the clock signal at the same frequency and phase of the digital data stream based on the phase adjustment signal.
2. The method of claim 1, wherein sampling said digital data stream to generate the sampled data signal is driven by a clock signal that is the inverse of said generated clock signal at the same frequency and phase of the digital data stream.
3. The method of claim 1, wherein sampling said digital data stream to generate the data edge clock signal is driven by said generated clock signal at the same frequency and phase of the digital data stream.
4. The method of claim 1, wherein generating the phase difference signal is performed by a phase difference detector.
5. The method of claim 1, wherein generating the phase difference signal includes:
de-multiplexing the sampled data signal and the data edge clock signal; and
determining whether the sampled data signal leads or lags the data edge clock signal.
6. The method of claim 5, wherein the sampled data signal and the data edge clock signal are de-multiplexed by a ratio of 20.
7. The method of claim 5, wherein determining whether the sampled data signal leads or lags the data edge clock signal is performed by a majority voter.
8. The method of claim 1, wherein adjusting the bandwidth of the of loop filter is performed using a loop lock detector.
9. The method of claim 8, wherein said loop lock detector includes a low pass filter.
10. The method of claim 1, wherein said operating modes are based on the relative phase difference between the sampled data signal and the data edge clock signal.
11. The method of claim 10, wherein said operating modes include an operating mode corresponding to a large loop filter bandwidth setting when the relative phase difference between the sampled data signal and the data edge clock signal is above a programmed threshold value.
12. The method of claim 10, wherein said operating modes include an operating mode corresponding to a small loop filter bandwidth setting when the relative phase difference between the sampled data signal and the data edge clock signal is below a programmed threshold value.
13. The method of claim 1, wherein said loop filter includes a proportional control branch and an integral control branch.
14. A system for recovering a clock signal and a data signal of a digital data stream, the system comprising:
at least one data input for carrying the digital data stream;
a data edge transition sampler in communication with the at least one data input;
a data sampler in communication with the at least one data input;
a phase difference detector in communication with the data edge transition sampler and the data sampler, configured to generate a phase difference signal based on the outputs of the data edge transition sampler and the data sampler;
a loop filter in communication with the phase difference detector, configured to generate a phase adjustment signal based on the phase difference signal;
a lock detector in communication with the loop filter, configured to adjust the bandwidth of the loop filter based on predetermined operating modes; and
a phase interpolator in communication with the output of the loop filter, configured to generate the clock signal at the same frequency and phase of the digital data stream using the phase adjustment signal.
15. The system of claim 14, wherein said data edge transition sampler is driven by said generated clock signal at the same frequency and phase of the digital data stream.
16. The system of claim 14, wherein said data sampler is driven by the inverse of said generated clock signal at the same frequency and phase of the digital data stream.
17. The system of claim 14, further including a signal de-multiplexer in communication with either the data edge transition sampler or the data sampler and the phase difference detector.
18. The system of claim 17, wherein the signal de-multiplexer has the capability of de-multiplexing the sampled signals of the data edge transition sampler and the data sampler by a ratio of 20.
19. The system of claim 14, wherein the phase difference detector includes a majority voter configured to determine whether the output of the data sampler leads or lags the output of the data edge transition sampler.
20. The system of claim 14, wherein the loop filer includes a proportional control branch and an integral control branch.
21. The system of claim 14, wherein the lock detector includes a low pass filter.
22. The system of claim 14, wherein said operating modes are based on the relative phase difference between the outputs of the data sampler and the data edge transition sampler.
23. The system of claim 14, wherein said operating modes include an operating mode corresponding to a large loop filter bandwidth setting when the relative phase difference between the outputs of the data sampler and the data edge transition sampler is above a programmed threshold value.
24. The system of claim 14, wherein said operating modes include an operating mode corresponding to a small loop filter bandwidth setting when the relative phase difference between the outputs of the data sampler and the data edge transition sampler is below a programmed threshold value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical modulator comprising:
a first and a second waveguide arm for receiving and transmitting therethrough first and second light beams, respectively;
a first and a second electrode structure associated with said first and second waveguide arms respectively; and
a driving circuit for supplying a voltage to said first and second electrode structures,
said driving circuit being adapted to supply a first modulation voltage superimposed to a first bias voltage to the first electrode structure and a second modulation voltage superimposed to a second bias voltage to the second electrode structure, a peak to peak amplitude of the first modulation voltage being different from a peak to peak amplitude of the second modulation voltage.
2. The optical modulator according to claim 1, wherein the first and second waveguide arms are substantially of the same length.
3. The optical modulator according to claim 1, further comprising a third electrode structure associated with one of the first and second waveguide arms.
4. The optical modulator according to claim 3, wherein the driving circuit is adapted to supply to the third electrode structure a continuous wave voltage.
5. The optical modulator according to claim 1, wherein the driving circuit is adapted to supply the first and second modulation voltage as electric signals having the same waveform.
6. The optical modulator according to claim 5, wherein the driving circuit is adapted to supply the electric signals with inverted sign.
7. A transmitting station comprising an optical transmitter device, the optical transmitter device comprising an optical source for providing an optical light beam at a predetermined wavelength and an optical modulator according to claim 1, associated with the optical source to modulate the intensity of the optical light beam.
8. The transmitting station according to claim 7, wherein the optical transmitter device further comprises an electro-optical converter adapted to convert an input modulated light beam at a generic wavelength into a corresponding modulation electric signal, the electro-optical converter being coupled to the optical modulator so as to supply said corresponding modulation electric signal to the driving circuit of the optical modulator.
9. An optical communication system comprising a transmitting station according to claim 7, and an optical communication line having a first end coupled to the transmitting station.
10. The optical communication system according to claim 9, further comprising a receiving station coupled to a second end of the optical communication line.
11. An optical communication system comprising a transmitting station comprising:
an optical transmitter device wherein said optical transmitter device comprises an optical source for providing an optical light beam at a predetermined wavelength and an optical modulator according to claim 1, associated with the optical source to modulate the intensity of the optical light beam;
an electro-optical converter; and
an optical communication line having a first end coupled to the transmitting station,
the optical modulator and the electro-optical converter comprising a unit adapted to convert an input optical light beam into a corresponding electrical signal.
12. The optical modulator according to claim 1, further comprising:
an optical splitter for splitting an input light beam into the first and second light beams; and
an optical combiner connected to the first and second waveguide arms for combining the first and second light beams into the output light beam.
13. The optical modulator according to claim 12, wherein the first and second waveguide arms each comprise a core region comprising a group IV semiconductor material or a combination of group IV semiconductor materials.
14. The optical modulator according to claim 13, wherein the optical splitter is a symmetric splitter adapted to split the input light beam into the first and second light beams of substantially the same optical power.
15. The optical modulator according to claim 13, wherein the group IV semiconductor material of each core region is selected from the group of Si and Ge and a combination thereof.
16. The optical modulator according to claim 13, comprising a silicon substrate with said optical modulator integrated thereon.
17. A unit comprising:
an optical modulator comprising:
an optical splitter for splitting an input light beam into a first and a second light beam;
a first and a second waveguide arm connected to said optical splitter for receiving and transmitting therethrough said first and second light beams, respectively, said first and second waveguide arms each comprising a core region comprising a group IV semiconductor material or a combination of group IV semiconductor materials;
an optical combiner connected to said first and second waveguide arms for receiving said first and second light beams and combine said first and second light beams into an output light beam;
a first and a second electrode structure associated with said first and second waveguide arms respectively; and
a driving circuit for supplying a voltage to said first and second electrode structures,
said driving circuit being adapted to supply a first modulation voltage superimposed to a first bias voltage to the first electrode structure and a second modulation voltage superimposed to a second bias voltage to the second electrode structure, and
an electro-optical converter adapted to convert the input light beam into a corresponding electrical signal.
18. The unit according to claim 17, wherein the electro-optical converter is coupled to the optical modulator so as to supply the corresponding electrical signal to the driving circuit of the optical modulator.
19. The unit according to claim 17, further comprising a filtering element.
20. The unit according to claim 19, wherein the filtering element is coupled to the electro-optical converter.
21. The unit according to claim 19, wherein the filtering element is coupled to the optical modulator.
22. The unit according to claim 19, wherein the filtering element comprises a drop filtering element coupled to the electro-optical converter and an add filtering element coupled to the optical modulator.
23. The unit according to claim 17, wherein at least a portion of the electro-optical converter comprises a group IV semiconductor material or a combination of group IV semiconductor materials.
24. The unit according to claim 23, wherein the electro-optical converter and the optical modulator are integrated on a silicon substrate.
25. The unit according to claim 19, wherein the filtering element comprises a material selected from the group of a group IV semiconductor material, SiO2, doped SiO2, Si3N4, SiON and a combination thereof.
26. The unit according to claim 19, wherein the electro-optical converter, the optical modulator and the filtering element are integrated on a silicon substrate.
27. A method for modulating an intensity of an optical signal comprising the steps of:
a) propagating first and second light beams along a first and a second optical path, respectively; and
b) introducing through Franz-Keldysh effect a relative phase shift between the first and second optical paths so as to obtain an intensity modulation of an output light beam;
wherein the step of introducing through the Franz-Keldysh effect is carried out by supplying a first modulation voltage superimposed to a first bias voltage to the first optical path and a second modulation voltage superimposed to a second bias voltage to the second optical path, a peak to peak amplitude of the first modulation voltage being different from a peak to peak amplitude of the second modulation voltage.
28. The method according to claim 27, further comprising supplying to at least one of the first and second optical paths a continuous wave voltage for introducing a further prefixed relative phase shift between the first and second optical paths.
29. The method according to claim 27, wherein a relative phase shift of \u03c0 or an integer odd multiple thereof is introduced for obtaining a 0 logic state and a relative phase shift of zero or an integer even multiple of iv is introduced for obtaining a 1 logic state.
30. The method according to claim 29, wherein the first and second modulation voltages are electric signals having the same waveform.
31. The method according to claim 30, wherein the electric signals have an inverted sign.
32. The method according to claim 31, wherein the first and second bias voltages and the first and second modulation voltages are such as to induce through the Franz-Keldysh effect an overall phase shift in the first and second optical paths which is substantially the same in absolute value but opposite in sign when passing from the 1 logic state to the 0 logic state, and vice versa.
33. The method according to claim 32, wherein the first bias voltage is substantially the same as the second bias voltage.
34. The method according to claim 32, wherein the first bias voltage is different from the second bias voltage.
35. The method according to claim 31, wherein the first and second bias voltages and the first and second modulation voltages are such as to induce through the Franz-Keldysh effect an overall phase shift in the first and second optical paths which is different in absolute value and sign, when passing from the 1 logic state to the 0 logic state, and vice versa.
36. The method according to claim 35, wherein the first bias voltage is different from the second bias voltage.
37. The method according to claim 27, comprising:
splitting a light beam into the first and second light beams; and
combining the first and second light beams into an output light beam after propagation along the first and second optical paths.
38. The method according to claim 37, wherein each of the first and second optical paths comprises a group IV semiconductor material or a combination of group IV semiconductor materials.
39. The method according to claim 38, wherein the light beam is split into the first and second light beams of substantially the same optical power.
40. A method for modulating an intensity of a light beam comprising the steps of:
a) splitting the light beam into a first and a second light beam;
b) propagating said first and second light beams along a first and a second optical path, respectively;
c) combining said first and second light beam into an output light beam after propagation along the first and second optical paths; and
d) introducing through Franz-Keldysh effect a relative phase shift between the first and second optical paths so as to obtain an intensity modulation of the output light beam;
wherein the step of introducing through the Franz-Keldysh effect is carried out by supplying a first modulation voltage superimposed to a first bias voltage to the first optical path and a second modulation voltage superimposed to a second bias voltage to the second optical path,
wherein in step d) a relative phase shift of \u03c0 or an integer odd multiple thereof is introduced for obtaining a 0 logic state and a relative phase shift of zero or an integer even multiple of \u03c0 is introduced for obtaining a 1 logic state,
wherein the first and second modulation voltages are electric signals having the same waveform,
wherein the electric signals have an inverted sign,
wherein the first and second bias voltages and the first and second modulation voltages are such as to induce through the Franz-Keldysh effect an overall phase shift in the first and second optical paths which is substantially the same in absolute value but opposite in sign when passing from the 1 logic state to the 0 logic state, and vice versa,
wherein the first bias voltage is different from the second bias voltage, and
wherein a peak to peak amplitude of the first modulation voltage is different from a peak to peak amplitude of the second modulation voltage.