An easy-to-fabricate but very efficient fiber-to-waveguide coupler is theoretically analyzed and experimentally demonstrated. In this design, light from a single-mode fiber can be butt-coupled into a single-mode high-index-contrast Si3N4/SiO2 waveguide with a measured coupling efficiency of 96 % at the wavelength of 1550 nm, and > 90 % in the spectral range from 1450 nm to 1650 nm. Large horizo...

Abstract—In this paper, a novel wideband directional coupler using coplanar waveguide multilayer slot-coupled technique is presented and implemented. The coupler uses two coplanar waveguide lines etched on two layers and coupled through an hexagonal slot etched on the common ground plane located between these layers. Firstly, conformal mapping techniques were used to obtain analytic closed-form...

We have designed and fabricated an out-of-plane coupler for butt-coupling from fiber to compact planar waveguides. The coupler is based on a short second-order grating or photonic crystal, etched in a waveguide with a low-index oxide cladding. The coupler is optimized using mode expansion-based simulations. Simulations using a 2-D model show that up to 74% coupling efficiency between single-mod...

Optical nanoantennas can be used for coupling radiation to or from waveguides in analogy to micro- and radio-wave systems. In this letter we provide a systematic description of the design approaches for a coupler to a plasmonic slot waveguide in the telecom range around 1.55 µm with realistic excitation from a lensed optical fiber. We show that the best coupling efficiency of 26% can be achieve...

in this paper a novel all-optical logic nand, nor and xor gate based on nonlinear directional coupler theory is demonstrated. we use the identical structure which contains three waveguides, for designing these gates; the only difference however, is the power of inputs light beam. in other words, while a beam with 4 w/μm in power considered as logical one, the output is nand gate and if a beam w...

Abstract— This paper presented the design of four-port network directional coupler at X-band frequency (8.2-12.4 GHz) by using substrate integrated waveguide (SIW) technique. SIW appears few years back which provides an excellent platform in order to design millimeter-wave circuits such as filter, antenna, resonator, coupler and power divider. It offers great compensation for smaller size and c...

We propose a novel grating coupler design which is inherently reflectionless by focusing the reflected light away from the entrance waveguide. The design rules for this reflectionless grating coupler are explained and the grating coupler design is investigated by means of 3D FDTD simulations for the case of a Silicon-on-Insulator based platform.

We propose an efficient optical coupler between a submicrometer-sized silicon waveguide on a silicon photonic chip and a multi-micrometer wide polymer waveguide on an optical printed circuit board for interchip optical networks. We show low coupling loss <0.4 dB with high lateral and angular tolerance to misalignment so that coupling can be done by automatic pick-and-place equipments with high ...

Asymmetric directional coupling between a hybrid plasmonic waveguide with subwavelength field confinement and a conventional dielectric waveguide is investigated. The proposed hybrid coupler features short coupling length, high coupling efficiency, high extinction ratio, and low insertion loss; it can also be integrated into a silicon-based platform. This coupler can be potentially adopted for ...