Investigation of ultrafast all-optical AND gate based on cascaded SOAs and optical filters

Abstract

We propose an ultrafast all-optical logic AND gate based on two cascaded SOA-OF configurations. Each SOA-OF consists a semiconductor optical amplifier (SOA) followed by an optical filter (OF) which reshapes the spectrum of the modulated probe light. A delayed interferometer (DI) and a tunable band pass filter (TNBPF) are chosen as OFs in the first and second SOA-OF. 40Gbit/s AND operation with 33% duty cycle return-to-zero (RZ) signals has been successfully demonstrated with SOAs whose 10%~90% recovery time are measured much larger than the time duration of one bit period. The quality factor (QF) and the extinction ratio (ER) of the eye diagram of the derived AND results were 6.3 and 8.8dB respectively. Numerical analysis and experimental demonstration with 40Gbit/s nonreturn-to-zero (NRZ) signals is also presented and shows that in order to achieve good AND result at the second stage, the differential time delay of the DI must be shorter than the single bit period of the input signals. The proposed AND gate takes the advantage of high speed WC realized by SOA-OF which displays flexibility to various data rates, pulse width as well as data formats.