Low-loss coplanar waveguides interconnects on low-resistivity silicon substrate

This paper describes fabrication, characterization and simulation of low-loss coplanar waveguide (CPW) interconnects on low-resistivity silicon substrate. The fabrication of CPWs is low-temperature (below 250/spl deg/C) and incorporates a spin-on low-k dielectric benzocyclobutene (BCB) and self-aligned electroplating of copper. The performance of CPWs is evaluated by high-frequency characterization and EM simulation. CPWs with different line width (W) and line spacing (S) are investigated and compared. Using a BCB layer as thick as 20 /spl mu/m, CPW fabricated on a low-resistivity silicon substrate exhibits an insertion loss of 3 dB/cm at 30 GHz.     

Low-loss singlemode waveguide and fibre bends

A new theoretical strategy for reducing bend loss is presented. It is based on the concept of introducing both depressed and increased index regions into the cladding of planar waveguides on the outside of the bent core. A similar strategy can be applied to optical fibres. In both cases, the bending loss is reduced beyond that achievable with the presence of depressed regions alone in the cladding     

Low-loss Na-glass waveguides

A new method for the fabrication of low-loss Na-glass waveguides on SiO2has been found. The reglassification process has enabled us to reduce the scattering loss in the planar waveguide to less than 1 dB/cm and to obtain channel waveguide with 2 dB/cm attenuation by the lift-off method or by the direct laser writing method.     

Low-loss singlemode fibre 1/spl times/2 Y-junction

A new method for the fabrication of a singlemode fibre wavelength independent Y-junction is described; through asymmetrically tapering a pre-assembled Y-junction precursor, the splice point is drawn into the waist region of the device and low-loss is ensured. The lowest loss and flattest wavelength response for such a device is reported.     

Low-loss silicon-on-insulator photonic crystal waveguides

Silicon-on-insulator-based 2D photonic crystal waveguides have been optically characterised. The measured total insertion loss is below 19 dB in the waveguides with unpolarised light. With the length mask technique, it is found that the photonic crystal waveguides show propagation losses below 4 dB/mm     

Low-loss high-silica single-mode channel waveguides

Low-loss high-silica single-mode channel optical waveguides of 0.1 dB/cm have been fabricated on crystal silicon substrates with fibre coupling losses of less than 0.05 dB by flame hydrolysis deposition and reactive ion etching. Directional couplers have also been fabricated with excess loss of 0.5 dB by this waveguide fabrication technique.     

Low-loss microwave interconnections by using polymeric based coplanar waveguides on low resistivity silicon substrates

In this paper a new approach to manufacture low losses coplanar waveguide (CPW) lines for microwave and millimeter wave signal processing is presented. A photolithographic process is performed by using SU-8 thick negative photo-resist on low resistivity silicon wafers, to obtain CPW lines elevated with respect to the substrate, in order to take advantages, in terms of propagation losses, from transmission line structures which are almost on-the-air.     

Low-loss propagation in photonic crystal waveguides

The fabrication and characterisation of high-quality silicon membrane photonic crystals are reported. The etching process was carefully optimised to give holes with very smooth and vertical sidewalls, resulting in propagation, with a minimum loss of 4.1plusmn0.9 dB/cm in a single line defect (W1) waveguide     

Low-loss optical branching waveguides consisting of anisotropicmaterials

Low-loss branching waveguides of the mode-conversion type consisting of anisotropic materials are proposed, and their basic wave-guiding characteristics are studied by means of coupled-mode theory. Two mode-conversion sections are introduced on both input and output sides of a conventional symmetric branching waveguide. Each arm of the branching waveguides is assumed to be a single-mode slab waveguide except for the tapered section. A coupled-mode system of equations describing mode-conversion phenomena with respect to the transverse magnetic (TM) mode in the branching waveguides is derived from the field expansion in terms of local normal modes. A Runge-Kutta-Gill method is used to numerically solve the coupled-mode equations. It is found that the proposed branching waveguides suffer mode-conversion losses to a much lesser extent than conventional branching waveguides     

Time-delay measurement in singlemode, low-loss photonic crystal waveguides

The group delay in low-loss, singlemode, 1 mm-long photonic crystal slab waveguides is measured using the phase shift technique for the first time. Low group velocities (相似文献   

Low-loss polymeric optical waveguides fabricated with deuteratedpolyfluoromethacrylate

Deuterated polyfluoromethacrylate which has high transparency, low birefringence and good processability was newly synthesized for use as optical waveguide materials, and both single-mode and multimode optical waveguides were fabricated using the polymer. The propagation loss and waveguide birefringence of the single-mode waveguides were as low as 0.10 dB/cm and -5.5×10^-6 at 1.31 μm, respectively. The propagation losses of the multimode waveguides were less than 0.02 dB/cm at both 0.68 and 0.83 μm, and 0.07 dB/cm at 1.31 μm     

Low-loss bends in planar optical ridge waveguides

Bending losses lower than 0.7 dB for 90° bend sections with radii of curvature as small as 75 μm were measured on silicon-based Al₂O₃ ridge waveguides with SiO₂ cladding layers at a wavelength of 632.8 nm. These values, which are close to the calculated values, are the lowest thus far reported     

Low-loss GaAs/AlGaAs optical waveguides on InP substrates

It is shown that the waveguide losses in lattice-mismatched GaAs-on-InP structures can be significantly reduced using an appropriate buffer layer. An AlGaAs buffer layer sequence was used for this purpose. A thin (400 nm) layer of Al_0.7Ga_0.3As, with an index below that of InP, was placed adjacent to the GaAs guiding layer both to maximize optical confinement in the guide and to increase the allowable guide dimensions for a single planar waveguide mode. Additional separation between guide and mismatched interface was achieved by inserting an Al_0.5Ga_0.5As layer with an index nearly equal to that of InP between the low-index buffer and InP. The final waveguide structure also included a thin (<40 nm) GaAs layer which was used to initiate growth and did not affect waveguide performance. Low losses (typically 3 dB/cm, with best results below 1 dB/cm) were achieved at a 1.52-μm wavelength for samples grown by organometallic chemical vapor deposition     

Low-loss multifibre connectors with plug-guide-grooved silicon

Low-loss interchangable multifibre connectors have been developed using plugs consisting of large guiding grooved and fibre-fixing V-grooved silicon chips. Guiding grooves etched on silicon chips accomplish extremely small average fibre offset less than 2 ?m. A 6-fibre connector plug pair selected from the same wafer exhibits 0.14 dB average connection loss. Connector plugs from different wafers exhibit 0.17 dB and 0.24 dB average connection losses.     

Low-loss coupling of multiple fiber arrays to single-mode waveguides

A method for obtaining permanent low-loss couping between arrys of single-mode fiber and Ti:LiNbO3waveguides is described. The technique, based on the use of silicon chip V-grooves, simplifies the coupling problem by simultaneously aligning the entire array and by providing a large surface area for a higher integrity adhesive bond. Atlambda = 1.3 mum, we measure an average 1.9-dB coupling loss (exclusive of propagation loss) for the assembled array. The average excess loss due to the fiber array is 0.8 dB. We present an analysis of the effect of various types of array misalignment on coupling efficiency. Angular alignment and array periodicity are found to be critical. If the fiber and waveguide periodicities are matched exactly, the fibers need only be placed withinpm 1.3mum of their optimum position to maintain coupling efficiencies greater than 90 percent.     

Low-loss straight and curved ridge waveguides in LPE-grown GaInAsP

Loss measurements on ridge waveguides in LPE-grown GaInAsP at a wavelength of 1.3 mu m are presented. An attenuation of 4.5 dB/cm has been obtained for straight waveguides, and for curved waveguides an excess loss at low as 0.7 dB was found for a 20.8 degrees S-bend with a radius of 300 mu m ( approximately=1.5 dB/90 degrees ).<>     

Low-loss single-mode InP/InGaAsP waveguides grown by MOVPE

Losses as low as 0.4 ± 0.1 dB/cm for TE- and 0.65 ± 0.1 dB/ cm for TM-polarised light have been observed in tightly confined single-mode InP/lnGaAsP waveguides grown by MOVPE and processed using RIE. These are the lowest losses reported for InP-based waveguides. The structure could be used to make low-loss modulators for communications wavelengths.     

Low-loss sapphire waveguides for 75-110 GHz frequency range

Low-loss dielectric waveguides are promising for use instead of metal ones, but problems in transitions have to be overcome. A simple and effective structure made of a monocrystalline sapphire waveguide has been designed. Experimental results at 75-110 GHz indicate good matching with metal waveguides (VSWR ⩽1.13) and low insertion loss (0.05-0.35 dB for 47 mm dielectric section)     

Low-loss, single-mode, organic polymer waveguides utilizingrefractive index tailoring

Low-loss, single-mode optical waveguides have been fabricated from photopolymerizable acrylic monomers. The material system consists of a low-index cladding resin and a high-index core resin. The two resins are miscible so that precise control over the refractive index can be obtained. This allows the fabrication of single-mode waveguides with specific cross-sectional dimensions. One advantage of this is the ability to fabricate waveguides with high coupling efficiencies to other devices such as optical fiber or semiconductor lasers. The materials adhere to a wide variety of substrates and exhibit average waveguide losses of 0.56 dB/cm at 1300 nm for single-mode waveguides. Details of the fabrication procedure, index of refraction tailoring technique, and waveguide loss data are presented     

Low-loss fibre-pigtailed 256 channel arrayed-waveguide gratingmultiplexer using cascaded laterally-tapered waveguides

A fibre-pigtailed 25 GHz-spacing 256 channel arrayed-waveguide grating (AWG) module has been fabricated. The module was composed of an AWG chip with a Δ of 1.5%, a fan-out planar lightwave circuit (PLC) with a A of 0.75%, an input fibre and two 128 fibre arrays. To improve the coupling loss of the 256 output fibres, a new PLC-fibre connection using cascaded laterally-tapered waveguides was developed. The fibre-pigtailing loss is reduced to only 1.1 dB and a multiplexer with a low insertion loss of 1.9-3.9 dB is realised