All optical sampling orthogonal frequency division multiplexing systems

A novel all-optical sampling orthogonal frequency division multiplexing (AOS-OFDM) scheme with optical cyclic postfixes (OCP) inserted is proposed and demonstrated. Ultra short pulses are used as optical samples and processed by forward and inverse discrete Fourier transform (DFT/IDFT) modules in optical domain. Optical CPs can be added in the proposed optical DFT modules, which can eliminate optical gates and simplify the receiver structure. In this scheme, high speed real-time OFDM system can be realized without limitation of electronic digital processing. AOS-OFDM system is suitable for different modulation formats, and it has better spectral efficiency and dispersion tolerance than traditional single-carrier optical systems. Compared to coherent OFDM system, it has better fiber nonlinearity tolerance for the low peak to average power ratio (PAPR) induced with fewer sub-carriers.