Bit-rate and format conversion from 10-Gbit/s WDM channels to a 40-Gbit/s channel using a monolithic Sagnac interferometer integrated with parallel-amplifier structure

Full bit-rate conversion from 10-Gbit/s random wavelength-division multiplexing (WDM) channels to a 40-Gbit/s channel, including non-return-to-zero (NRZ) to return-to-zero (RZ) format conversion and reconversion, was successfully demonstrated. The key technique is wavelength conversion using a monolithic Sagnac interferometer integrated with a parallel-amplifier structure. Good eye-openings through the 10-Gbit/s NRZ to 40-Gbit/s RZ, and 40-Gbit/s RZ to 10-Gbit/s NRZ conversions were obtained. Error-free operation and a small power penalty of less than 0.8 dB were achieved. Phase adjustment of 10 Gbit/s signals was also successfully demonstrated with slight wavelength conversions using a planar lightwave circuit and semiconductor optical amplifier hybrid integrated Mach-Zehnder interferometer.