Coupled-mode equations for an asymmetric fibre-to-planar optical coupling system, incorporated a grating structure are presented. A grating-assisted coupling coefficient is described. When the parameters of the coupler are such that there is no phase synchronism between the fibre and the slab modes, the grating enhances the coupling in both the resultant amplitude and phase modulation. However,...

We propose and demonstrate all-optical mode-selective wavelength conversion in a silicon waveguide. The mode-selective wavelength conversion relies on strong four-wave mixing when pump and signal light are on the same spatial mode, while weak four-wave mixing is obtained between different modes due to phase mismatch. A two-mode division multiplexing circuit with tapered directional coupler base...

We report simulation results for a directional coupler between silicon waveguides in different layers of a threedimensional (3D) optical circuit. The coupling length is 1.4 mm. The device is manufacturable using standard CMOS technology provided individual waveguide layers can be vertically stacked. In simulations of coupling efficiency the design exhibits negligible loss with respect to transl...

We have developed a powerful parallel genetic algorithm design tool for photonic crystal and waveguide structures. The tool employs a small-population-size genetic algorithm (microgenetic algorithm) for global optimization and a two-dimensional finite-difference time-domain method to rigorously design and optimize the performance of photonic devices. We discuss the implementation and performanc...

Abstract: Alteration of a geometry parameter in the cross section of a dielectric waveguide with piecewise constant permittivity profile can be regarded as a refractive index perturbation in a layer along a dielectric discontinuity line. Starting from these thin layer perturbations, we derive explicit expressions for partial derivatives of propagation constants with respect to the transverse wa...

A novel design of all-optical logic gates based on nonlinear slot waveguide couplers is proposed. NOT, OR, and AND logic gates can be realized by simple single optical directional coupler configuration. Strong polarization dependencies of slot waveguides are effectively utilized for realizing polarization-independent optical directional couplers in linear regime and polarization-dependent all-o...

We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-...

The electron flow through quantum waveguides is modeled by the time-dependent Schrödinger equation with absorbing boundary conditions, which are realized by a negative imaginary potential. The Schrödinger equation is discretized by a time-splitting spectral method, and the quantum waveguides are fed by a mono-energetic incoming plane wave pulse. The resulting algorithm is extremely efficient du...

Analysis of cylindrical integrated optical microresonators involves the coupling between a straight waveguide and a bent waveguide. Our (2D) variant of coupled mode theory is based on analytically represented mode profiles. With the bend modes expressed in Cartesian coordinates, coupled mode equations can be derived in a classical way, and solved by numerical integration. Proper manipulation of...

A miniature optical spectrometer with a thin-film planar waveguide grating coupler in combination with a miniature plano-convex focusing lens has been investigated. With optical part of the spectrometer as small as 0.2 cubic cm, the spectral resolution varies from 0.3 nm to 4.6 nm within the wavelength range 488.0 nm - 632.8 nm.