On-Chip All-Optical Wavelength Conversion of PAM-4 Signals Using an Integrated SOA-Based Turbo-Switch Circuit

We experimentally demonstrate on-chip all-optical wavelength conversion (AOWC) of four-level pulse amplitude modulation (PAM-4) signals by cross-gain modulation in an InP monolithically integrated turbo-switch circuit based on semiconductor optical amplifiers (SOAs). Full characterization of the photonic integrated circuit (PIC) is given, where sevenfold reduction in effective gain recovery is achieved by the PIC turbo-switch compared with a case of single SOA switch. Wavelength conversion of 25 Gbit/s PAM-4 signal in the C-band is successfully demonstrated with ~2 dB power penalty at 1 × 10
^-3
bit error rate. Moreover, the wavelength dependence of the converter is studied. The integrated AOWC device has the advantages of high-speed switching operation as well as small footprint, high stability, and low switching power.