Programmable optical processor achieves multichannel OTDM-to-WDM conversion

Scientists at the Universidade de Aveiro (Aveiro, Portugal) and Nokia Siemens Networks Portugal (Amadora, Portugal) have created an optical time-division multiplexing (OTDM) to wavelength-division multiplexing (WDM) converter that handles multichannel conversion with flexibility in both time and wavelength domains, thus opening up the possibility of getting OTDM and WDM systems to work together in a straightforward manner. The converter relies on a so-called programmable optical processor (POP) to do its work.

Part of a 160 Gbit/s input data signal from an OTDM with N different signal “tributaries,” or channels, feeds a clock-recovery system, which provides a clean optical clock signal that is then split into N different wavelengths, with the resulting signal pulses (SPs) processed by the POP to suppress amplified-spontaneous-emission and other noise. Via four-wave mixing in a highly nonlinear optical fiber, the rest of the OTDM signal interacts with the multiwavelength sampling pulse train. The time delays and shapes of the SPs are controlled through adjusting the POP’s phase and amplitude function, respectively. An output tunable optical filter filters the resulting signals, producing a 4 × 40 Gbit/s WDM output. Error-free performance was achieved for all signals, with a maximum power penalty of 6.3 dB. Tweaking of the system parameters can further reduce the power penalty. Contact Miguel Drummond at [email protected].