Coherent OCDMA receivers with robust performance

Optical code division multiple access can achieve good spectral efficiency, a high degree of security, and soft degradation in many network applications. Robust performance in the presence of key impairments is achieved by careful selection of encoding sequences according to correlation properties and spread-time pulse shapes. A new, coherent receiver retrieves transmitted information coherently without phase locking or fast nonlinear detectors, while minimizing multiple access interference and cancelling beat noise. A key design improvement prevents link outage caused by random states of polarization without requiring polarization management.