Experimental implementations of continuous optical time domain Fourier transformation based on time lenses and optical orthogonal frequency-division multiplexing (OFDM) system are carried out. Such a system is verified through 100-km transmission of 10-Gb/s non-return-to-zero (NRZ) intensity-modulated direct-detection (IM-DD) without any dispersion compensation. The system's bit error rate (BER) and power penalty are 10^-12 and 4 dBm, respectively.

A novel method for distortion-free optical pulse transmission is theoretically proposed and simulated, in which two time lenses formed by dispersion fibers and quadratic phase modulations are utilized. One is used as an optical inverse Fourier transformation (OIFT) device to transform the initial time-domain data to frequency-domain one at the transmitter and the other as an optical Fourier transformation (OFT) device to recover the data at the receiver. By using the unchanged spectral envelope in linear optical fiber communication, the initial data can be recovered. Through simulations, a 10\times100 Gb/s intensity-modulated direct-detection (IM-DD) dense wavelength division multiplexing (DWDM) system over 2000-km transmission without the compensation for polarization mode dispersion (PMD) and dispersion slope is achieved, which can be used to upgrade the current 10-Gb/s IM-DD system to a 100-Gb/s one directly.