System and method for producing high-precision electrical signals and continuous-wave optical signals

• US 9,647,770 B1
• Filed: 10/23/2015
• Issued: 05/09/2017
• Est. Priority Date: 10/23/2015
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Wilkinson, Steven R., Shamee, Bishara
• Primary Examiner(s): Leung, Danny
• Application Number:
  US14/921,146
• Publication Number:
  US 20170117970A1
• Time in Patent Office: 564 Days
• CPC Class Codes: H01S 5/06226 Modulation at ultra-high frequencies
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/2507 for the reduction or elimination of distortion or dispersion
• CPC Class Codes: H04B 10/541 Digital intensity or amplitude modulation
• CPC Class Codes: H04B 10/548 Phase or frequency modulation
• CPC Class Codes: H04B 10/572 Wavelength control
• CPC Class Codes: H04B 10/70 Photonic quantum communication
• CPC Class Codes: H04L 7/0075 with photonic or optical means

Abstract

A photonic oscillator can produce a multifrequency optical signal having a spectrum that includes regularly spaced spectral lines. A photodetector can convert the multifrequency optical signal to a multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines. A bandpass filter can attenuate all but one spectral line of the spectrum of the multifrequency electrical signal to form a single-frequency electrical signal having leading/trailing edges that have the same precision as the photonic oscillator. A continuous-wave laser can lock to the multifrequency optical signal and produce a continuous-wave optical signal at a wavelength precisely locked to the photonic oscillator. A data encoder/decoder can modulate/demodulate a data stream onto/from the continuous-wave optical signal at a data rate of the single-frequency electrical signal. The modulated optical signal can be clocked with the leading/trailing edges of the single-frequency electrical signal.

Claims

1. A system, comprising:

a photonic oscillator configured to produce a multifrequency optical signal having a spectrum that includes regularly spaced spectral lines;

a first photodetector configured to convert the multifrequency optical signal to a first multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines;

a first bandpass filter configured to attenuate all but a first spectral line of the spectrum of the first multifrequency electrical signal to form a first single-frequency electrical signal at the frequency of the first spectral line; and

a first continuous-wave laser configured to lock to the multifrequency optical signal and produce a first continuous-wave optical signal at a first wavelength in response to the multifrequency optical signal.

2. The system of claim 1, further comprising a data encoder configured to:

receive a digital data stream representing digital data;

modulate the first continuous-wave optical signal to include the digital data, the modulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce a modulated optical signal at the first wavelength and modulated at the frequency of the first spectral line.

3. The system of claim 2, wherein the data encoder is further configured to modulate the first continuous-wave optical signal using quadrature amplitude modulation.

4. The system of claim 1, further comprising a data decoder configured to:

receive a modulated optical signal at the first wavelength and modulated at the frequency of the first spectral line;

demodulate the modulated optical signal to extract digital data encoded on the modulated optical signal, the demodulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce a digital data stream representing the extracted digital data.

5. The system of claim 4, wherein the data decoder is further configured to demodulate the modulated optical signal using quadrature amplitude demodulation.

6. The system of claim 1, further comprising:

a second photodetector configured to produce a second multifrequency electrical signal in response to the multifrequency optical signal, the second multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines;

a second bandpass filter configured to attenuate all but a second spectral line of the spectrum of the second multifrequency electrical signal to form a second single-frequency electrical signal at the frequency of the second spectral line; and

a second continuous-wave laser configured to lock to the multifrequency optical signal and produce a second continuous-wave optical signal at a second wavelength in response to the multifrequency optical signal.

7. The system of claim 6, wherein the second wavelength is different from the first wavelength.

8. The system of claim 6, wherein the first and second spectral lines correspond to the same frequency.

9. The system of claim 6, further comprising:

a data encoder configured to;

receive a digital data stream representing transmittable digital data;

modulate the first continuous-wave optical signal to include the transmittable digital data, the modulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce an output modulated optical signal at the first wavelength and modulated at the frequency of the first spectral line; and

a data decoder configured to;

receive an input modulated optical signal at the second wavelength and modulated at the frequency of the second spectral line;

demodulate the input modulated optical signal to extract received digital data encoded on the input modulated optical signal, the demodulation being synchronized to the second single-frequency electrical signal at the frequency of the second spectral line; and

produce an input digital data stream representing the received digital data.

10. A system, comprising:

a photonic oscillator configured to produce a multifrequency optical signal having a spectrum that includes regularly spaced spectral lines;

a photodetector configured to convert the multifrequency optical signal to a multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines;

a bandpass filter configured to attenuate all but a first spectral line of the spectrum of the multifrequency electrical signal to form a single-frequency electrical signal at the frequency of the first spectral line;

a first continuous-wave laser configured to lock to the multifrequency optical signal and produce a first continuous-wave optical signal at a first wavelength in response to the multifrequency optical signal;

a second continuous-wave laser configured to lock to the multifrequency optical signal and produce a second continuous-wave optical signal at a second wavelength in response to the multifrequency optical signal.

11. The system of claim 10, wherein the second wavelength is different from the first wavelength.

12. The system of claim 10, further comprising a data encoder configured to:

receive a digital data stream representing digital data;

modulate the first continuous-wave optical signal to include the digital data, the modulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce a modulated optical signal at the first wavelength and modulated at the frequency of the first spectral line.

13. The system of claim 12, wherein the data encoder is further configured to modulate the first continuous-wave optical signal using quadrature amplitude modulation.

14. The system of claim 10, further comprising a data decoder configured to:

receive a modulated optical signal at the second wavelength and modulated at the frequency of the first spectral line;

demodulate the modulated optical signal to extract digital data encoded on the modulated optical signal, the demodulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce a digital data stream representing the extracted digital data.

15. The system of claim 14, wherein the data decoder is further configured to demodulate the modulated optical signal using quadrature amplitude demodulation.

16. A system, comprising:

a photonic oscillator configured to produce a multifrequency optical signal having a spectrum that includes regularly spaced spectral lines;

a first photodetector configured to convert the multifrequency optical signal to a first multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines;

a first bandpass filter configured to attenuate all but a first spectral line of the spectrum of the first multifrequency electrical signal to form a first single-frequency electrical signal at the frequency of the first spectral line;

a plurality of continuous-wave lasers configured to lock to the multifrequency optical signal and produce respective continuous-wave optical signals at respective wavelengths in response to the multifrequency optical signal, the wavelengths of the continuous-wave optical signals are different from one another.

17. The system of claim 16, further comprising:

a second photodetector configured to convert the multifrequency optical signal to a second multifrequency electrical signal having a spectrum that includes the regularly spaced spectral lines; and

a second bandpass filter configured to attenuate all but a second spectral line of the spectrum of the second multifrequency electrical signal to form a second single-frequency electrical signal at the frequency of the second spectral line.

18. The system of claim 17, further comprising a plurality of data encoders, each data encoder of the plurality configured to:

receive a digital data stream representing digital data;

modulate the respective continuous-wave optical signal to include the digital data, the modulation being synchronized to the first single-frequency electrical signal at the frequency of the first spectral line; and

produce a respective modulated optical signal at the respective wavelength and modulated at the frequency of the first spectral line.

19. The system of claim 18, further comprising a plurality of data decoders, each data decoder of the plurality configured to:

receive a respective modulated optical signal at the respective wavelength and modulated at the frequency of the second spectral line;

demodulate the modulated optical signal to extract digital data encoded on the modulated optical signal, the demodulation being synchronized to the second single-frequency electrical signal at the frequency of the second spectral line; and

produce a digital data stream representing the extracted digital data.

20. The system of claim 19, wherein:

each data encoder is further configured to modulate the respective continuous-wave optical signal using quadrature amplitude modulation;

each data decoder is further configured to demodulate the respective modulated optical signal using quadrature amplitude demodulation; and

the frequencies of the first and second spectral lines are equal.