A novel microstrip coupled-line directional coupler is proposed in this paper. It is based on the introduction of a complementary split ring resonator and dumbbell-like defected ground structure on the coupled lines to strongly enhance the designed backward coupling. The designed frequency band is from 1.2 to 1.5GHz. The coupler is fabricated and tested. The insertion loss is less than 3.5 dB. ...

A polarization-independent optical directional coupler based on slot waveguides is proposed and analyzed by using rigorous full-vectorial analysis methods based on a finite-element scheme. Properly choosing materials and structural parameters makes the coupling length for quasi-TE modes become equal to that for quasi-TM modes. Tolerances to operating wavelength and structural parameters are als...

In this paper a novel design of all-optical half-subtractor based on nonlinear directional coupler is proposed. By using four waveguides and appropriately adjusting the refractive indices and selecting the proper length of waveguides, halfsubtractor function can be obtained. The operation of this function is simulated by RSoft CAD-Layout (BeamPROP) simulator. The simulation results confirm the ...

Soliton switching in a nonlinear directional coupler (NLDC) with Kerr nonlinearity and coupling constant dispersion (caused by intermodal dispersion between the symmetric and the anti-symmetric modes of the coupler) is studied using the well-known variational method. Switching characteristics are calculated and discussed. It is shown that the switching characteristics of the Kerr coupler for al...

Directional mode coupling in an asymmetric holey fiber coupler is demonstrated both numerically and experimentally for the first time. The holey fiber mode couplers have interesting spectral characteristics and are also found to exhibit increased dimensional tolerances. Following a design based on numerical investigations, a dual-core polymer holey fiber coupler for LP(01) and LP(11) mode multi...

We analyze hybrid plasmonic waveguides with metallic layers on two sides. Confinement of closely stacked metal induces large difference of effective indices of vertical even and odd modes. This phenomenon can be utilized as ultracompact vertical directional coupler. Simulation shows directional coupling can be achieved in less than 1 μm.

The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching of solitons between the arms. Power losses accompanying the switching can be fully compensated by using a c...

We suggest a novel scheme for multistep cascaded parametric processes based on a periodically poled nonlinear directional coupler and derive the conditions for simultaneous phase matching of the second-harmonic generation and sum-frequency mixing processes. We predict an efficient wavelength conversion by the cascaded third-harmonic generation from the third optical communication window (1.53-1...

A novel, wideband, symmetrical, printed directional coupler is described, which has tight coupling and high directivity. The coupler consists of four interconnected strips printed in two layers. The dimensions of the strips are optimized to minimize the dispersion of propagating modes. Design data are provided for some typical practical cases. The theoretical results are verified experimentally...