Differential ring modulator

Patent metadata

Field	Value
Publication number	US-2016306201-A1
Application number	US-201615070665-A
Country	US
Kind code	A1
Filing date	Mar 15, 2016
Priority date	Mar 16, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

A differential optical modulator includes, in part, a splitter splitting an incoming optical signal into first and second input signals, a first variable coupler generating a first differential output signal in response to the first input signal, and a second variable coupler generating a second differential output signal in response to the second input signal. The first variable coupler includes, in part, first and second couplers and a phase shifter disposed therebetween. The first coupler generates a pair of internal signals in response to the first input signal. The second coupler generates the first differential output signal. The second variable coupler includes, in part, third and fourth couplers and a phase shifter disposed therebetween. The third coupler generates a pair of internal signals in response to the second input signal. The fourth coupler generates the second differential output signal.

First claim

What is claimed is:

1 . A differential optical modulator comprising:
a splitter adapted to split an incoming optical signal into first and second input signals; a first variable coupler adapted to generate a first differential output of the optical modulator in response to the first input signal; a second variable coupler adapted to generate a second differential output of the optical modulator in response to the second input signal, wherein said first variable coupler is further adapted to generate a first internal signal applied to the second variable coupler, and wherein said second variable coupler is further adapted to generate a second internal signal applied to the first variable coupler.

2 . The differential optical modulator of claim 1 wherein said first variable coupler comprises:
a first coupler adapted to generate third and fourth internal signals in response to the first input signal and the second internal signal;
a second coupler adapted to generate the first differential output signal and the first internal signal in response to the first coupler; and
a first phase shifter disposed between the first and second couplers.

3 . The differential optical modulator of claim 2 wherein said second variable coupler comprises:
a third coupler adapted to generate fifth and sixth internal signals in response to the second input signal and the first internal signal;
a fourth coupler adapted to generate the second differential output signal and the second internal signal in response to the third coupler; and
a second phase shifter disposed between the third and fourth couplers.

4 . The differential optical modulator of claim 3 further comprising:
a thermal phase shifter adapted to match phases of the first and second input signals.

5 . The differential optical modulator of claim 4 wherein each of the first and second phase shifters comprises a p-n junction adapted to vary the phase shifter's optical length in response to a voltage applied thereto.

6 . The differential optical modulator of claim 5 wherein the second phase shifter receives a complement of a first voltage applied to the first phase shifter.

7 . The differential optical modulator of claim 6 wherein said first variable coupler comprises a third phase shifter disposed between the first and second couplers, and wherein said second variable coupler comprises a fourth phase shifter disposed between the third and fourth couplers.

8 . The differential optical modulator of claim 7 wherein each of the third and fourth phase shifters comprises a p-n junction adapted to vary the phase shifter's optical length in response to a voltage applied thereto.

9 . The differential optical modulator of claim 8 wherein said third phase shifter receives the first voltage and the fourth phase shifters receives the complement of the first voltage.

10 . The differential optical modulator of claim 9 wherein each of the first, second, third and fourth couplers is a 3-dB coupler.

11 . The differential optical modulator of claim 1 wherein each of said first and second variable couplers has an associated optical ring, wherein at any given time either the first variable coupler or the second variable coupler couples power to the coupler's associated ring.

12 . A method of modulating an incoming optical signal, the method comprising:
splitting the incoming optical signal into first and second input signals; generating a first optically modulated differential output signal in response to the first input signal; and generating a second optically modulated differential output signal in response to the second input signal.

13 . The method of claim 12 further comprising:
generating the first optically modulated differential output signal via a first coupler; and
generating a second optically modulated differential output signal via a second coupler, wherein said first coupler is responsive to the second coupler, and wherein said second coupler is responsive to the first coupler.

14 . The method of claim 13 further comprising:
generating first and second internal signals via a third coupler responsive to the second coupler; and
generating third and fourth internal signals via a fourth coupler responsive to the first coupler.

15 . The method of claim 14 further comprising:
delaying a phase of the first internal signal to generate a first delayed signal; and
applying the first delayed signal to the first coupler.

16 . The method of claim 15 further comprising:
delaying a phase of the fourth internal signal to generate a second delayed signal; and
applying the second delayed signal to the second coupler.

17 . The method of claim 16 further comprising:
generating the first delayed signal in response to a first voltage; and
generating the second delayed signal in response to a complement of the first voltage.

18 . The method of claim 17 further comprising:
delaying a phase of the second signal to generate a third delayed signal; and
applying the third delayed signal to the first coupler.

19 . The method of claim 18 further comprising:
delaying a phase of the third signal to generate a fourth delayed signal; and
applying the fourth delayed signal to the second coupler.

20 . The method of claim 19 further comprising:
generating the third delayed signal in response to the complement of the first voltage; and
generating the fourth delayed signal in response to the first voltage.

21 . The method of claim 20 wherein each of the first, second, third and fourth couplers is a 3-dB coupler.

22 . The method of claim 13 wherein each of said first and second variable couplers has an associated optical ring, wherein at any given time either the first variable coupler or the second variable coupler couples power to the coupler's associated ring.

Assignees

• California Inst Of Techn

Inventors

• Saeedi Saman
• Abiri Behrooz
• Emami Azita
• Hajimiri Seyed Ali

Classifications

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title

• G02F2203/50

  Phase-only modulation · CPC title

• H04B10/541

  Digital intensity or amplitude modulation · CPC title

• G02B6/293

  with wavelength selective means · CPC title

• G02B6/38

  having fibre to fibre mating means · CPC title