Polarization-insensitive and widely tunable wavelength conversion for polarization shift keying signal based on four wave mixing in highly non-linear fiber.

A fiber-based polarization-insensitive and widely tunable all-optical wavelength conversion for polarization shift keying (PolSK) signal is experimentally demonstrated by means of four-wave-mixing (FWM) in highly non-linear fiber. Polarization sensitivity of our scheme is compared with the conventional one and the conversion performance of the PolSK signal is investigated. In our scheme, preservation of state of polarization (SOP) of input PolSK signal is possible on both of the converted spectral components in FWM spectrum. In addition, over 23 nm of wavelength tunable operation with high conversion performance is achieved and detailed bit-error-rate (BER) characteristics are measured for both the up- and down-converted signal.