Multifunctional optical logic device based on nanoscale rectangular ring resonator

Integrated optical logic devices are essential building blocks for implementing all-optical arithmetic and logic unit. In this paper, an ultra-compact multifunctional optical logic device consisting of a rectangular ring resonator coupled with two parallel metal–insulator–metal waveguides is presented. The transmission characteristics of the structure are analyzed in detail via temporal coupled-mode theory. The finite-difference time-domain simulation results reveal that multiple logic functions can be implemented with the aid of the wavelength division multiplexing technique at different output ports. Specifically, all seven basic types of logic gates, half-adder, half-subtractor, and 2*4 decoder can be implemented by monitoring the transmission of through and drop ports at different wavelengths. More importantly, among these functions, six logic gates (OR, XNOR, NAND, NOR, XOR, and AND) and half-adder functions can be performed simultaneously; the NOT logic operation is performed with controllable output ports and selectable working wavelengths; the half-subtractor and 2*4 decoder functions can be operated simultaneously. The proposed logic device is characterized by a small area overhead, multifunctionality, fast response time, and ultrahigh-speed information processing. It may potentially be applied in on-chip universal and parallel photonic computing units.