Perfectly synchronized bit-parallel WDM data transmission over a single optical fiber

We demonstrate a bit-level synchronization technique by conducting a bit-parallel wavelength-division-multiplexed (WDM) data transmission over 27.5 km of optical fiber. Multiple WDM channels, which may represent individual bits in a byte or a word in parallel computer input-output, are transmitted in the optical fiber in non-return-to-zero format. These bits experience time skew due to group velocity dispersion. By sampling with an all-optical switch in the range where all these bits overlap, we obtained perfectly synchronized WDM signals. The synchronized WDM channels are demultiplexed with an array waveguide grating. Bit error rates below 10^-10 are measured for each channel. The spectral range of the experimental demonstration covers about 24 nm with the smallest wavelength separation of 1.4 nm, enough to pack 16 bits into the span. More bits are available if smaller channel-separation and wider spectral span are employed.