Equilateral Triangle Arrangement Research Articles

Switching in three-core nonlinear fiber coupler with second order coupling dispersion coefficient

The propagation and switching of fundamental solitons in three-core fiber nonlinear directional coupler with three cores in an equilateral-triangle arrangement have been investigated with two methods. Firstly, by using variational method, we obtained the equation of transmission coefficient with respect to distance. Secondly, we used the split-step Fourier method (SSFM) to solve the nonlinear Schrdinger equations. The results of both variational method and SSFM indicate that the energy of optical pulses transfer periodically between the three cores and have sharp switching characteristics when the first order intermodal dispersion coefficient is small. Otherwise, the periodicity of the coupling transmission characteristics of optical solitons in fiber coupler and the sharpness of switching are destroyed. The second order intermodal dispersion coefficient and initiative chirp reduce the coupling length, shorten the periods of the energy transfer of optical pulses between the three cores, and increase the threshold switching power. Though the cross phase modulation coefficient has weaker impact on transmission characteristics, it increases the threshold switching power of couplers.

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.

Stir Bars in Miniature

MICROFLUIDICS Mixing fluids at micrometer size is challenging because of the increasing importance of surface effects on fluid motion and because of difficulties associated with the miniaturization of mechanical systems. Barbic et al. have added another option to the microfluidics designer's toolbox by devising a small-scale analog of the magnetic stirrer. They created a long cylindrical stir bar using electrodeposition of nickel into a porous substrate. The rotor retained its magnetization parallel to its long axis and thus did not need to be magnetized by an outside source. The stator assembly was made from three soft ferromagnetic core wires, each of which was manually wound with a current-carrying wire and etched in order to focus the magnetic field. The cores were positioned in an equilateral triangle arrangement, and the sinusoidal current in each wire was 120° out of phase with its neighbors, thus causing the rotor to rotate. Lower viscosity fluids allowed higher rotation rate but with less control over the lateral motion of the rotor. Such a micromotor system could be used to form a micro pump, stirrer, or flow control valve. — MSL Appl. Phys. Lett. 79 , 1399 (2001).

Nonadditive Interactions in Trimers Containing H2, N2, and O2

A study comparing the magnitudes of the second-order nonadditive induction energy and the nonadditive triple-dipole dispersion energy for interactions in trimers containing the linear homonuclear molecules H2, N2, and O2 has been undertaken. The configurations are a linear, symmetric and an equilateral triangle arrangement of the trimers: H2−H2−H2, N2−N2−N2, O2−O2−O2, N2−N2−O2, and O2−N2−H2. The observed trends are discussed.

Anisotropy of non-additive energies for interactions in some trimers containing homonuclear molecules

The second-order non-additive induction energy for interactions in trimers containing the linear homonuclear molecules H2, N2 and O2 has been computed for two different configurations via expressions recently derived using the MAPLE symbolic computational language. The configurations are a linear, symmetric and an equilateral triangle arrangement of the trimers: H2–H2–H2, N2–N2–N2, O2–O2–O2, N2–N2–O2, N2–H2–O2 and O2–N2–H2. The induction energies are compared with the corresponding triple-dipole dispersion energies for the two different configurations. The significance of these results is also discussed.