Segmenting silicon waveguides at the subwavelength scale produce an equivalent homogenous material. The geometry of waveguide segments provides precise control over modal confinement, effective index, dispersion and birefringence, thereby opening up new approaches to design devices with unprecedented performance. Indeed, ever-improving lithographic technologies offering sub-100-nm patterning resolution in photonics platform, many practical based on structures have been demonstrated recent...

Abstract Nanophotonic beamsplitters are fundamental building blocks in integrated optics, with applications ranging from high speed telecom receivers to biological sensors and quantum splitters. While high‐performance multiport have been demonstrated several material platforms using multimode interference couplers, their operation bandwidth remains fundamentally limited. Here, we leverage the inherent anisotropy dispersion of a sub‐wavelength structured photonic metamaterial demonstrate...

We propose an ultra-broadband multimode interference (MMI) coupler with a wavelength range exceeding the O, E, S, C, L and U optical communication bands. For first time, dispersion property of MMI section is engineered using subwavelength grating structure to mitigate dependence device. present 2 × design bandwidth 450nm, almost fivefold enhancement compared conventional designs, maintaining insertion loss, power imbalance phase deviation below 1dB, 0.6dB 3°, respectively. The performed...

We explore, to the best of our knowledge, potential diffractionless subwavelength grating waveguides for sensing applications. show that by patterning silicon-wire field delocalization can be engineered increase sensitivity. Fully vectorial 3D-FDTD simulations confirm sensitivity enhancement, achieving sensitivities 0.83 RIU/RIU and 1.5·10(-3) RIU/nm bulk surface sensing, respectively, which compare favorably state-of-the-art waveguides.

Directional couplers are extensively used devices in integrated optics, but suffer from limited operational wavelength range. Here we use, for the first time, dispersive properties of sub-wavelength gratings to achieve a fivefold enhancement operation bandwidth silicon-on-insulator directional coupler. This approach does not compromise size or phase response device. The grating based coupler propose covers 100 nm with an imbalance ≤ 0.6 dB between its outputs, as supported by full 3D FDTD...

We present several fundamental photonic building blocks based on suspended silicon waveguides supported by a lateral cladding comprising subwavelength grating metamaterial.We discuss the design, fabrication, and characterization of waveguide bends, multimode interference devices Mach-Zehnder interferometers for 3715 -3800 nm wavelength range, demonstrated first time in this platform.The propagation loss 0.82 dB/cm is reported, some lowest yet achieved range.These results establish direct...

Fiber-chip edge couplers are extensively used in integrated optics for coupling of light between planar waveguide circuits and optical fibers.In this work, we report on a new fiber-chip coupler concept with large mode size silicon photonic wire waveguides.The allows direct conventional cleaved fibers while circumventing the need lensed fibers.The is designed 220 nm silicon-on-insulator (SOI) platform.It exhibits an overall efficiency exceeding 90%, as independently confirmed by 3D...

Surface grating couplers are fundamental components in chip-based photonic devices to couple light between integrated circuits and optical fibers. In this work, we report on a coupler with sub-decibel experimental coupling efficiency using single etch process standard 220-nm silicon-on-insulator (SOI) platform. We specifically demonstrate subwavelength metamaterial refractive index engineered nanostructure backside metal reflector, the measured peak fiber-chip of -0.69 dB (85.3%) 3 bandwidth...

We present a new type of mid-infrared silicon-on-insulator (SOI) waveguide. The waveguide comprises sub-wavelength lattice holes acting as lateral cladding while at the same time allowing for bottom oxide (BOX) removal by etching. loss is determined wavelength 3.8 μm structures before and after being underetched using both vapor phase liquid hydrofluoric acid (HF). A propagation 3.4 dB/cm was measured design with 300 nm grating period 150 partial (560 nm) BOX HF also demonstrate an...

We present the first experimental demonstration of a new fiber-chip grating coupler concept that exploits blazing effect by interleaving standard full (220 nm) and shallow etch (70 trenches in 220 nm thick silicon layer. The high directionality is obtained controlling separation between deep to achieve constructive interference upward direction destructive toward substrate. Utilizing this concept, can be maximized independent bottom oxide thickness. also includes subwavelength-engineered...

Silicon photonic biosensors hold the potential for highly accurate, yet low cost point-of-care devices. Maximizing sensitivity of sensing chips while reducing complexity and read-out system is pivotal to realize this potential. Here we present an extensive analysis, both from a practical theoretical perspective, current biosensors, analyze how subwavelength structures can be exploited enhance their sensitivity. This study not restricted just near-infrared band as also determine capabilities...

In this Letter, we report suspended silicon waveguides operating at a wavelength of 7.67 μm with propagation loss 3.1 0.3 dB∕cm.To our knowledge, is the first demonstration low-loss such long wavelength, comparable to other platforms that use more exotic materials.The Si waveguide core supported by sub-wavelength grating provides lateral optical confinement while also allowing access buried oxide layer so it can be wet etched using hydrofluoric acid.We demonstrate bends and s-bends.

Current bandwidth capacity provided by wavelength-division multiplexing and polarization-division is insufficient to keep up with the increasing demand required for new services. Mode-division technology paves way further increase transmission capacities in photonic interconnects. In this work, we propose an ultra-broadband two-mode converter de/multiplexer based on a sub-wavelength engineered multimode interference coupler, 90° phase shifter, symmetric Y-junction silicon-on-insulator...

Properties of reflection and transmission spectral filters based on Bragg gratings in subwavelength grating (SWG) metamaterial waveguides silicon-on-insulator platform have been analyzed using proprietary 2D 3D simulation tools Fourier modal method the coupled-mode theory. We also demonstrate that coupled Bloch mode theory can be advantageously applied to design SWG waveguides. By combining different techniques, including judiciously positioning silicon loading segments within evanescent...

The design and fabrication of an ultracompact silicon-on-insulator polarization converter is reported. conversion with extinction ratio 16 dB achieved for a length only 10 μm. Polarization rotation by inducing vertical asymmetry forming in the waveguide core two subwavelength trenches different depths. By taking advantage calibrated reactive ion etch lag, depths are implemented using single mask etching process. measured loss -0.7 3 bandwidth 26 nm.

As most integrated optics platforms, silicon offers only a fixed set of material refractive indices for designing devices. The ability sub-wavelength patterned structures to synthesize arbitrary equivalent index values between nSi ~ 3.5 and nair=1 has thus enabled completely new design approaches that have led waveguide devices with breakthrough performance. This review covers the latest advances in structured fiber-to-chip grating couplers multimode interference couplers. We discuss, among...

We propose a multimode interference coupler (MMI) design for high-index-contrast technologies based on shallowly etched region, which is, the first time to our knowledge, directly coupled deeply input and output waveguides. This reduces phase errors associated with high-index contrast, while still allowing very compact layout. Using this structure, we fabricate 2×4 MMI operating as 90° hybrid, footprint of only 0.65mm×0.53mm, including all structures necessary couple light fiber array....

Abstract Grating couplers are key elements enabling the coupling of light between planar waveguide circuits and optical fibers. In this work, it is demonstrated using simulations experiments that a high efficiency can be achieved for an arbitrary buried oxide thickness by judicious adjustment grating radiation angle. The coupler strength engineered subwavelength structure, allowing straightforward apodization single etch step fabrication. design has been implemented Fourier‐eigenmode...

We present a tool to aid the design of periodical structures, such as subwavelength grating (SWG) structures.It is based on Fourier Eigenmode Expansion Method and includes Floquet modes theory.Besides, most interesting implemented functionalities ease photonic devices are detailed.The capabilities shown using it analyse three different SWG devices.

We propose a fiber-chip grating coupler that interleaves the standard full and shallow etch trenches in 220 nm thick silicon layer to provide directionality upward exceeding 95%. By adjusting separation between two sets of trenches, constructive interference is achieved direction independent bottom oxide thickness without any reflectors, overlays, or customized depths. implement transverse subwavelength structure first periods minimize back-reflections. The has calculated coupling efficiency...

Subwavelength gratings (SWG) are photonic structures with a period small enough to suppress diffraction, thereby acting as artificial dielectric materials, also called all-dielectric metamaterials. This property has been exploited in many high-performance integrated devices the silicon-on-insulator (SOI) platform. While SWG waveguides theoretically lossless, they may exhibit leakage penalty substrate due combination of reduced modal confinement and finite thickness buried oxide (BOX) layer....

Subwavelength grating (SWG) structures are an essential tool in silicon photonics, enabling the synthesis of practical metamaterials with controllable refractive index.Here we propose, for first time, tilting elements to gain control over anisotropy metamaterial.Rigorous FDTD simulations demonstrate that a 45°tilt results effective index variation on fundamental TE mode 0.23 units, whereas change TM is 20 times smaller.Our simulation predictions corroborated by experimental results.We...

Abstract Graded‐index materials offer virtually complete control over light propagation in integrated photonic chips but can be challenging to implement. Here, an anisotropic graded‐index metamaterial, synthesized with fully etched silicon subwavelength structures, is proposed. Based on this material, a spot size converter that expands the transverse electric (TE) mode field profile from 0.5 µm wide wire waveguide 15 within length of only 14 designed. Measured insertion losses are below 1 dB...