All-optical dual-wavelength conversion based on cross-polarization modulation and its application to format conversion from amplitude-shift keying to frequency-shift keying

Simultaneous noninverted and inverted dual-wavelength conversion is proposed and demonstrated by using a cross-polarization modulation effect in a semiconductor optical amplifier (SOA). Experiments show that noninverted and inverted conversions lead to power penalties of 1.3 dB and 0.8 dB, respectively, at a bit rate of 10 Gb/s. Based on this scheme, we have demonstrated, for the first time to our knowledge, an all-optical modulation format conversion from amplitude-shift keying (ASK) to frequency-shift keying (FSK). A frequency-shift keying signal with flexible tone spacing and high bit rate can be successfully generated by using this method.