Method and apparatus for encoding optical power and non-payload data in an optical signal

• US 7,346,284 B2
• Filed: 12/19/2006
• Issued: 03/18/2008
• Est. Priority Date: 12/29/1999
• Status: Expired due to Fees

• Current Assignee: Ciena Corporation
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Wan, Ping Wai
• Primary Examiner(s): Bello; Agustin
• Application Number:
  US11/612,916
• Publication Number:
  US 20070122162A1
• Time in Patent Office: 455 Days
• Field of Search: 398202-214
• US Class Current: 398/202
• CPC Class Codes: H04B 10/5161 Combination of different modulation schemes
• CPC Class Codes: H04B 10/541 Digital intensity or amplitude modulation
• CPC Class Codes: H04B 10/5561 Digital phase modulation
• CPC Class Codes: H04L 27/2096 Arrangements for directly or externally modulating an optical carrier optical modulation H04B10/503
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits

Abstract

A method and apparatus for encoding optical power and non-payload data in an optical signal is described. The method involves producing a dither modulating signal having an amplitude of indicative of the optical power in the optical signal and having a phase representing the non-payload data, and modulating the optical signal with the dither modulating signal. The apparatus involves a waveform generator for producing an amplitude adjusted waveform having an amplitude responsive to the optical power of the optical signal and a binary phase shift keying modulator for binary phase shift keying the amplitude adjusted waveform in response to the non-payload data to produce a dither modulating signal having an amplitude indicative of the optical power in the optical signal and having a phase representing the non-payload data.

Claims

1. A method of extracting non-payload data from an optical signal carrying both payload data and said non-payload data, said optical signal modulated with a dither modulating signal, said dither modulating signal being modulated by a binary phase shift keyed signal carrying said non-payload data, the method comprising:

a) producing an electrical representation of said optical signal;

b) demodulating said electrical representation to extract said binary phase shift keyed signal; and

c) demodulating said binary phase shift keyed signal to obtain said non-payload data.

2. The method as claimed in claim 1 wherein demodulating said electrical representation comprises filtering said electrical representation.

3. The method as claimed in claim 1 further comprising squaring said binary phase shift keyed signal to produce a tone signal having an amplitude representative of the power of said optical signal.

4. The method as claimed in claim 3 further comprising producing an amplitude value representative of the amplitude of said tone signal and determining the power of said optical signal from said amplitude value.

5. An apparatus for extracting non-payload data from an optical signal carrying payload data, said optical signal modulated with a dither modulating signal said dither modulating signal being modulated by a binary phase shift keyed signal carrying non-payload data, the apparatus comprising:

a) an optical to electrical signal converter for converting said optical signal into an electrical signal;

b) a first demodulator for demodulating said electrical signal to extract said binary phase shift keyed (BPSK) signal from said electrical signal; and

c) a BPSK demodulator for demodulating said binary phase shift keyed signal to obtain said non-payload data.

6. The apparatus as claimed in claim 5 wherein said first demodulator comprises a low pass filter.

7. A method of measuring optical power in individual optical signals of a composite optical signal, the method comprising:

a) converting the composite optical signal into a composite electrical signal;

b) demodulating the composite electrical signal to produce a composite dither signal comprised of a plurality of dither modulating signals; and

c) squaring the individual dither modulating signals to produce a composite squared signal including a plurality of tone signals representing optical power in respective individual optical signals.

8. The method as claimed in claim 7 wherein demodulating comprises filtering said electrical representation.

9. The method as claimed in claim 7 further comprising calculating an amplitude of at least one of said tone signals and computing said power from said amplitude.

10. An apparatus for measuring optical power in individual optical signals of a composite optical signal, the apparatus comprising:

a) an optical to electrical signal converter for converting the composite optical signal into a composite electrical signal;

b) a demodulator for demodulating the composite electrical signal to produce composite dither signal comprised of a plurality of dither modulating signals; and

c) a squarer for squaring the individual dither modulating signals to produce a composite squared signal including a plurality of tone signals representing optical power in respective individual optical signals.

11. The apparatus as claimed in claim 10 wherein said demodulator comprises a low pass filter for filtering said composite signal.

12. The apparatus as claimed in claim 10 further comprising a processor for calculating an amplitude of at least one of said tone signals and for computing said power from said amplitude.