Polarization-insensitive wavelength-division-multiplexing optical millimeter wave generation based on copolarized pump four wave mixing in a semiconductor optical amplifier.

We proposed a novel scheme to generate polarization-insensitive optical millimeter-wave (mm-wave) wavelength-division-multiplexing (WDM) signals by using an external modulator and a semiconductor optical amplifier (SOA). In the scheme, two copolarized pumps and a WDM signal are mixed in the SOA based on four wave mixing (FWM), and the quadruple frequency mm-wave signal, similar to the single-sideband mm-wave signal, is obtained by using an optical filter to remove one sideband after FWM. Based on the scheme, we have experimentally demonstrated the generation of a two-channel 2.5 Gbit/s WDM optical mm-wave signal with a repetitive frequency up to 40 GHz by a 10 GHz local oscillator, and the downstream signal delivery over a 20 km fiber with power penalty less than 1 dB.