Optical switches and all-fiber logical devices based on triangular and planar three-core nonlinear optical fiber couplers

In this paper, we investigate the switching process in a triangular (T) and planar (P1 and P2) symmetric three-core nonlinear fiber coupler (TNLDC) operating in the CW regime. We have numerically shown, via the coupled nonlinear Schrödinger equations (NLSEs), that AND, NAND, OR, NOR, XOR, NXOR and NOT logic gates can be constructed. The first configuration, a triangular (TNLDC-T) symmetrical structure, is composed with three cores in an equilateral-triangle arrangement and using a control signal (CS) applied to the first core. The P1 and P2 configurations presents a planar symmetrical structure with three cores in a parallel equidistant arrangement, with different input positions of the control signal (CS). In the P1 configuration the CS is applied to the input of the first fiber (core 1) while for the P2 configuration the CS is applied to the input of the central fiber (core 2). Looking at the transmission characteristics of the device, through the direct and cross channel, we did a study of the extinction ratio (XRatio(dB) of these devices. In comparing the performance of all switches operating as logic gates we will use the figure-of-merit of the logic gates (FOMELG(dB)) defined as a function of the extinction ratio of the gate outputs.