Spectrally phase encoded optical code division multiple access system

1. A system for transmitting user data over a network defined by a usable frequency band that includes a continuous frequency range, comprising:

an encoder that operates to encode a signal transmitted by a user to occupy a plurality of non-contiguous frequency bands within the continuous frequency range; and

an optical time gate that operates to temporally extract the signal transmitted by the user from among a plurality of other signals in the plurality of non-contiguous frequency bands.

2. The system of claim 1 , wherein the network comprises an optical network and the continuous frequency range is characterized by a set of discrete frequencies.

3. The system of claim 2 , further comprising a laser source for generating the set of discrete frequencies.

4. The system of claim 2 , wherein the non-contiguous frequency range comprises a subset of the set of discrete frequencies.

5. The system of claim 4 , wherein the encoder comprises a phase mask that encodes the phase of each discrete frequency that comprises the subset of discrete frequencies.

6. The system of claim 1 , wherein the encoder comprises a mask that operates to adjust the phase and amplitude of the user signal to convey the user signal over a plurality of non-contiguous frequency bands.

7. The system of claim 1 , wherein the mask uses a zero-padded orthogonal or quasi-orthogonal spreading sequence.

8. The system of claim 1 , wherein the network comprises a wireless network and the encoder comprises a pseudo-random phase encoder, the system further including a radio-frequency transmitter for transmitting the encoded signal onto the network.

9. An optical code division multiple access system, comprising:

a data modulator for receiving an optical pulse sequence having N spectral lines, and modulating the pulse sequence with a signal to produce a modulated signal;

a spectral encoder for encoding the amplitude and phase of the modulated signal, the encoder being operable to define a coding pattern having N symbols, each symbol being associated with a particular one of the N spectral lines of the modulated signal, and forming a plurality of non-contiguous spectral bands separated by one or more spectral gaps; and

an optical time gate for temporally extracting the signal from the modulated signal.

10. The system of claim 9 , further comprising means for transmitting the modulated signal using the one or more spectral gaps.

11. The system of claim 10 , wherein the means for transmitting includes a wavelength division multiplexer.

12. The system of claim 9 , wherein the data modulator comprises an on-off keyed modulator.

13. The system of claim 9 , wherein the spectral encoder comprises a phase mask filter that defines a phase shift for each of the N symbols.

14. The system of claim 13 , wherein the phase shift for each of the N symbols comprises an orthogonal or quasi-orthogonal code set.

15. A method for transmitting data, comprising:

modulating an optical pulse with user data, the modulated optical pulse comprising N-contiguous spectral lines;

encoding the modulated optical pulse such that the N-contiguous spectral lines are partitioned into two or more groups of non-contiguous spectral lines within the N-contiguous spectral lines, each of the groups being separated by a frequency band;

adding one or more signals to the encoded signal;

decoding the encoded signal to retrieve the modulated optical pulse; and

optically gating the modulated optical pulse to retrieve the user data.

16. The method of claim 15 , further comprising selecting an encoding sequence that is either a spreading sequence or its Fourier transform.