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,...

A compact silicon bandpass filter with high sidelobe suppression is proposed and experimentally demonstrated using an apodized subwavelength grating (SWG) coupler. The device is implemented by placing a SWG waveguide next to a strip waveguide, and apodization is employed with a Gaussian profile to taper the gap between the two waveguides. A high sidelobe suppression ratio of 27 dB can be obtain...

We propose an all-optical integrated nonreciprocal device on the optomechanical platform with a large nonreciprocal bandwidth and low operating power. The device is based on an asymmetric silicon coupler consisting of two branches. One of them is a conventional strip waveguide fixed on the substrate, and the other is a freestanding nanostring suspended above a groove in the substrate. When ligh...

We demonstrate the preparation and transmission of the lowest loss azimuthally polarized TE₀₁₋ like mode in a photonic band gap (PBG) fiber. Using the nature of the mode and the properties of the band gap structure we construct a novel coupler that operates away from the band gap's center to enhance the differential losses and facilitate the radiative loss of hybrid fundamental fiber modes. Rem...

We report our study on nonlinear parity-time (PT) symmetric coupler from a dynamical perspective. In the linear regime, the differential equations governing the dynamics of the coupler, under some parametric changes, can be solved exactly. But with the inclusion of nonlinearity, analytical solution of the system is a rather complicated job. And the sensitiveness of the system on the initial con...

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 describe the optical and mechanical design, construction philosophy, and testing of a pair of matched, spaceflight-qualified fiber couplers. The couplers were developed for the LISA Pathfinder mission but are relevant for other applications-both on ground and in space-where a robust fiber coupler with well-controlled beam parameters and stable beam pointing is required. This particular imple...

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...

An optical hybrid design based on paired multimode interference couplers in silicon-on-insulator process is investigated. The device exhibits greater than 20 dB CMRR and low phase deviation (<10) over 30 nm in the C-band. The design eliminates the use of optical cross waveguides for integration with balanced photodetectors. Introduction Coherent detection scheme provides high spectral efficienc...

PC Coupler DC bias Combiner Abstract— In this paper, all-optical signal processors that perform both microwave mixing and bandpass filtering in a radio-over-fiber (RoF) link are presented. The key device is a Mach-Zehnder modulator (MZM) which performs all-optical microwave mixing. An up-converted microwave signal is obtained and other unwanted frequency components are suppressed at the end of ...