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 ...

The wavelength response of a waveguide volume grating coupler (WVGC) is analyzed for coupling light from a slab waveguide into the superstrate. A leaky-mode approach is used in conjunction with rigorous coupled-wave analysis. A quantitative theoretical study of the effect of index modulation, waveguide index, and grating thickness on the wavelength bandpass of a WVGC is also presented. The FWHM...

Shifting the location of a dielectric boundary in the cross section of an integrated optical waveguide with piecewise constant refractive index profile results in a permittivity perturbation in a layer along the discontinuity line. On the basis of these thin layer perturbations, we discuss perturbational expressions for the derivatives of the propagation constants with respect to geometry param...

A variable coupling ratio Y-Branch plastic optical fiber (POF) coupler based on acrylic has been developed. This device utilized two optical designs: a Y-branch structure with a novel suspended waveguide taper and a simple attenuation technique based on lateral displacement of two fibers for the non-symmetrical coupling ratios. The high index contrast waveguide taper is constructed on the acryl...

in this article, we suggested a novel design of polarization splitter based on coupler waveguide on inp substrate at 1.55mm wavelength. photonic crystal structure is consisted of two dimensional (2d) air holes embedded in inp/ingaasp material with an effective refractive index of 3.2634 which is arranged in a hexagonal lattice. the photonic band gap (pbg) of this structure is determined using t...

We demonstrate that nonlinear directional coupler with special bending of waveguide axes can be used for all-optical switching of polychromatic light with very broad spectrum covering all visible region. The bandwidth of suggested device is enhanced five times compared to conventional couplers. Our results suggest novel opportunities for creation of all-optical logical gates and switches for po...

A high-performance and compact fiber-to-waveguide binary blazed subwavelength grating coupler was designed based on silicon-on-insulator. By the appropriate choice of waveguide/grating parameters, including thicknesses, periods, height, and fill factor, to optimize the mode matching, a relatively high coupling efficiency was obtained for the fiber and waveguide interface. Moreover, perfectly ve...

We theoretically investigate the properties of compact couplers between high-index contrast dielectric slab waveguides and two-dimensional metal-dielectric-metal subwavelength plasmonic waveguides. We show that a coupler created by simply placing a dielectric waveguide terminated flat at the exit end of a plasmonic waveguide can be designed to have a transmission efficiency of ~70% at the optic...

31.1 Silicon Photonics Fundamentals 31.1.1 A historical perspective 30.1.2 Silicon waveguide 30.2 Coupling Light to Silicon Waveguides 30.2.1 Problem of external coupling 30.2.2 Nonvertical taper (NVT) 30.2.3 Grating coupler 30.2.4 Nanotaper 30.3 Resonant Structures 30.3.1 Principle of directional coupling 30.3.2 Mach-Zehnder interferometers 30.3.3 Ring Resonators 30.4 Modulation of Optical Sig...