Abstract: Encoders and decoders for applying composite codes to optical data signals include encoders and decoders for applying both subcodes and supercodes. The subcodes have a duration selected as less than or equal to an interchip duration or a chip duration of the supercodes. The encoders and decoders (“coders”) include fiber Bragg gratings configured to encode or decode a subcode, a supercode, or a composite code. By coding with a subcode coder and a supercode coder, a coder is reconfigurable by selecting different subcodes or supercodes. Communication systems and methods using composite codes are also described.

Abstract: A waveguide that is operative to produce a reflected optical signal having a spectral profile corresponding to a product of a spectral profile of an input optical signal and a predetermined complex-valued spectral filtering function wherein the waveguide includes a plurality of spatially distinct subgratings each possessing a periodic array of diffraction elements. The subgratings are situated and configured based on the predetermined complex-valued spectral filtering function.

Abstract: Methods and apparatus for optical communication are disclosed. An optical data stream is encoded to produce an optical data stream having a predetermined time-wavelength spectrum. Two or more encoded data streams are combined in a transmission medium (e.g., optical fiber) and the combined data stream is decoded with decoders corresponding to the encoding of the data streams, producing decoded outputs. The decoded outputs include a portion corresponding to a selected data stream as well as a portion corresponding to unselected data streams (crosstalk). A nonlinear detector receives the decoded outputs and rejects crosstalk. Coders produce temporal delays and phase shifts specified by a time-wavelength code for, the spectral components of an input optical signal. Some coders convert optical signals encoded with a first time-wavelength code into an output corresponding to a second time-wavelength code. Temporal delays and phase shifts can be selected to compensate for dispersion in a transmission medium.

Abstract: Methods and apparatus are provided for the recognition of an optical signal that is encoded with a specified temporal pattern. Nonlinear optical interactions and time-integrating optical detectors are used to identify temporally short correlation peaks in an optical signal in an optical communication system without temporally resolving the correlation signal. The apparatus includes means for decoding an encoded optical waveform, a time-integrating nonlinear detection system, a time-integrating linear detection system for proper normalization, and thresholding electronics that produce voltage pulses corresponding to the presence of specified waveforms at the detector input.