Experimental AND and OR Logic Gates With MZI and SOA Using PAM Modulation

One of the main limitations of optical communication systems is the current need for optoelectronic conversions in intermediate devices, which do not reach the transmission rates of optical fibers of terabits per second. In this work, we investigated the obtaining of logic gates through a configuration of a Mach-Zehnder interferometer with a semiconductor optical amplifier (SOA) as the unbalancing element of the interferometer. We experimentally studied three different scenarios of input power for a continuous wave regime and one scenario for the PAM regime, both with varying levels of gain of the SOA. As a result, we obtained the AND and OR logic gates in all scenarios in a wide range of gain of the SOA, besides the logic functions 0 and 1 in some of the cases. We confirm the quality of these logic gates by the precision rate regarding the threshold of 0.4 dB above and below the central limit, according to recommendations from the literature. We highlight that the technique used in this experiment is much less complex than most of those described in the literature. The use of pulse amplitude modulation (PAM) suggests a simpler way for controlling logic gates, once we can obtain those by simply changing the injection current applied by the SOA. The experimental obtaining of such logic gates is relevant for all-optical logic circuits that are proposed to optimize the current optical communication systems.