A new approach to all-optical half-adder by utilizing semiconductor optical amplifier based MZI wavelength converter

Semiconductor optical amplifier (SOA) has already been established itself as a strong all-optical switching element for conducting super fast optical operations. Many all optical logic operations have been proposed by the use of SOA. Here in this paper the authors proposed a new method of implementing all-optical frequency encoded logic operations and half-adder by the use of SOA as well as Mach Zehnder interferometer. The advantage of frequency encoding has been strongly exploited here.     

Luminescence-based molecular scale logic circuits

We show how a half-adder logic circuit can be implemented on one molecule for a molecule exhibiting both S₁→S₀ and S₂→S₀ fluorescence. This is achieved by using both one photon S₀→S₁ excitation and consecutive S₁→S₂ excitation and establishing logic thresholds by utilizing the laser-induced photoquenching process. We present results pertaining to rhodamine and azulene molecules, in which, for the first time, an all optical half-adder logic circuit is implemented.