All-Optical Modulation-Format Convertor Employing Polarization-Rotation-Type Nonlinear Optical Fiber Loop Mirror

An all-optical modulation-format convertor with regenerative function based on fiber nonlinearity is proposed and demonstrated. The convertor was formed utilizing polarization- rotation-type nonlinear optical fiber loop mirror and could operate at both on-off keying (OOK) to OOK and OOK to phase-shift keying (PSK) format conversions only by simply rotating the optical axis of the intra lambda/2 waveplate, without excess-loss generation and realignment of the driving conditions of control optical signals in the format exchange. The 40-Gb/s OOK to OOK/PSK format conversions were successfully performed utilizing this new type of the all-optical convertor. The results also revealed that this convertor has a reshaping function to degraded control signals as an inline all-optical regenerator.