Photonic wavelength shifting method

• US 6,407,846 B1
• Filed: 03/16/2001
• Issued: 06/18/2002
• Est. Priority Date: 03/16/2001
• Status: Expired due to Fees

• Current Assignee: All Optical Networks, Inc.
• Original Assignee: All Optical Networks, Inc.
• Inventors: Myers, Michael H., Riley, Juan C., Guest, Clark C., Bablumyan, Arkady S., Melville, Charles D.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): CHOI, WILLIAM C
• Application Number:
  US09/810,888
• Time in Patent Office: 459 Days
• Field of Search: 359/238, 359/243, 359/244, 359/341, 359/113, 359/114, 359/130, 359/115, 359/118, 359/121, 359/124-128, 359/133, 359/158, 359/189, 359/195, 359/246, 359/326, 359/239, 385/20, 385/21.17, 385/18, 385/7, 385/36, 385/24, 385/22, 385/37, 385/39, 385/46, 385/5
• US Class Current: 359/239
• CPC Class Codes: G02F 2/00 Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light G02F1/35 takes precedence
• CPC Class Codes: H04B 10/505 using external modulation
• CPC Class Codes: H04B 10/5053 using a parallel, i.e. shunt, combination of modulators
• CPC Class Codes: H04B 10/5055 using a pre-coder
• CPC Class Codes: H04B 10/5057 using a feedback signal generated by analysing the optical output
• CPC Class Codes: H04B 10/572 Wavelength control
• CPC Class Codes: H04B 10/675 for controlling the optical bandwidth of the input signal, e.g. spectral filtering
• CPC Class Codes: H04B 10/69 Electrical arrangements in the receiver
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

A method for photonic wavelength shifting and stabilization is described. The method receives a photonic signal, comprised of one or more channels, and provides a wavelength shifted, stabilized, and channelized photonic signal. Data encoding is also supported. A modulation synthesizer provides a modulation waveform embedded with the shifting, stabilization and data encoding mechanisms. A variety of modulation techniques are supported. The modulation waveform is optimized for the particular modulation technique. A wavelength error detector provides feedback to the modulation synthesizer. The error signal is used to stabilize the photonic signal and correct channel wavelength errors. Fixed wavelength channels and spread spectrum channels are supported.

Claims

1. A method for providing a wavelength shifted and stabilized photonic signal, the method comprising:

providing a photonic input signal comprising at least one channel, each channel having a wavelength that is definable as a function of time;

providing a modulation waveform configured to shift the wavelength of the photonic input signal;

modulating the photonic input signal with the modulation waveform to shift the wavelength of each channel of the photonic input signal, thereby providing a photonic output signal comprising at least one channel, each channel having a wavelength that is definable as a function of time;

providing a wavelength reference;

comparing the wavelength reference with at least one channel of the photonic output signal to thereby providing an error signal configured to correct the wavelength of at least one channel of the photonic output signal;

adjusting the modulation waveform in accordance with the error signal; and

modulating the photonic input signal with the modulation waveform to correct the wavelength of the photonic output signal.

2. The method of claim 1, further comprising:

providing a data signal, and pre-modulating the modulation waveform in accordance therewith to encode the data signal into the photonic output signal.

3. The method of claim 2, wherein the data signal is encoded into the photonic output signal using Frequency Shift Keying.

4. The method of claim 3, wherein the Frequency Shift Keying comprises orthogonal codes.

5. The method of claim 2, wherein the data signal is encoded into the photonic output signal using ON/OFF Keying.

6. The method of claim 2, wherein the data signal is encoded into the photonic output signal by pre-modulating with orthogonal codes.

7. The method of claim 1, further comprising:

providing a shift signal; and

shifting the wavelength of the photonic output signal with respect to the wavelength of the photonic input signal, in proportion to the shift signal.

8. The method of claim 7, wherein the shift signal comprises a spreading function.

9. The method of claim 7, wherein the shift signal comprises a gathering function.

10. The method of claim 7, wherein the shift signal comprises the difference of two spreading functions.

11. The method of claim 7, wherein the shift signal comprises an allowable range of wavelength shifts.

12. The method of claim 1, wherein modulating the photonic input signal with the modulation waveform comprises phase modulation.

13. The method of claim 1, wherein modulating the photonic input signal with the modulation waveform comprises quadrature amplitude modulation.

14. The method of claim 13, wherein the modulation waveform is a quadrature waveform comprising first and second waveform components that are substantially 90 degrees out of phase.

15. The method of claim 14, wherein the first and second waveform components are substantially sinusoids divided by a transfer function of a modulation device.

16. The method of claim 14, wherein the first and second waveforms are substantially sawtooth in shape.

17. The method of claim 14, wherein the first and second waveforms are substantially triangular in shape.

18. The method of claim 1, wherein the modulation waveform is substantially sawtooth in shape.

19. The method of claim 1, wherein the modulation waveform is substantially triangular in shape.

20. The method of claim 1, wherein the wavelength reference is a wavelength pattern.

21. The method of claim 1, wherein the photonic output signal comprises a representative channel, and the wavelength reference is compared with the wavelength of the representative channel to provide an error signal configured to correct the wavelength of the representative channel of the photonic output signal.

22. The method of claim 1, wherein the wavelength reference is compared with the wavelength of multiple channels to provide an error signal configured to correct the wavelength of multiple channels of the photonic output signal.