Experimental implementation of an all-optical OFDM system based on time lens

A real time all-optical orthogonal frequency division multiplexing (OOFDM) system based on two time lenses is experimentally demonstrated. At the transmitter, groups of initial optical pulses are transformed into OOFDM symbols by a continuous inverse Fourier transform (IFT) device, which consists of the first a quadratic phase modulator and two high dispersive elements. After transmission, a continuous Fourier transform (FT) device, consisting of another quadratic phase modulator and two high dispersive elements, rebuilds the initial optical pulses at the receiver. The electrical sinusoidal waveform employed in the FT module at the receiver is obtained directly from the transmitter with certain phase shift. In the system, the guard interval is necessary for each OOFDM symbol to ensure the initial pulses are operated FT/IFT under a parabolic waveform driving and to have more Fourier transformation time window. Experiment results show that 8 × 2.5 Gb/s signals successfully transmit through 200-km-G.655 fibers without any dispersion compensation, with the BER being 10− 12.