The authors study suitable process parameters, and the resulting pattern formation, in additive layer-by-layer fabrication of arbitrarily shaped three-dimensional (3D) silicon (Si) micro- and nanostructures. The layer-by-layer fabrication process investigated is based on alternating steps of chemical vapor deposition of Si and local implantation of gallium ions by focused ion beam writing. In a final step, the defined 3D structures are formed by etching the Si in potassium hydroxide, where the ion implantation provides the etching selectivity.

Keywords: 3d, implantation, ion_beam, koh, kth_paper, mems, mst_paper, own_paper, silicon

A method for additive layer-by-layer fabrication of arbitrarily shaped 3D silicon micro- and nanostructures is reported. The fabrication is based on alternating steps of chemical vapor deposition of silicon and local implantation of gallium ions by focused ion beam (FIB) writing. In a final step, the defined 3D structures are formed by etching the silicon in potassium hydroxide (KOH), in which the local ion implantation provides the etching selectivity. The method is demonstrated by fabricating 3D structures made of two and three silicon layers, including suspended beams that are 40 nm thick, 500 nm wide, and 4 .m long, and patterned lines that are 33 nm wide.

Keywords: 3d, experiment, fib, first_paper, gallium, implantation, ion_beam, koh, mems, own_paper, processing, si3dnl, silicon

We present the design, fabrication, and characterization of a grating for coupling between a single mode silica fiber and the TE mode in a silicon photonic waveguide on a silicon on insulator (SOI) substrate. The grating is etched completely through the silicon device layer, thus permitting the fabrication of through-etched surface coupled silicon nanophotonic circuits in a single lithography step. Furthermore, the grating is apodized to match the diffracted wave to the mode profile of the fiber. We experimentally demonstrate a coupling efficiency of 35% with a 1 dB bandwidth of 47 nm at 1536 nm on a standard SOI substrate. Furthermore, we show by simulation that with an optimized buried oxide thickness, a coupling efficiency of 72% and a 1 dB bandwidth of 38 nm at 1550 nm is achievable. This is, to our knowledge, the highest simulated coupling efficiency for single-etch TE-mode grating couplers. In particular, simulations show that apodizing a conventional periodic through-etched grating decreases the back-reflection into the waveguide from 21% to 0.1%.

Keywords: apodized, camfr, coupler, design_optimization, experiment, for:antelius, grating, kth_paper, mst_paper, own_paper, silicon, silicon_oxide, simulation, soi, waveguide

We present an experimental study of an integrated slot-waveguide refractive index sensor array fabricated in silicon nitride on silica. We study the temperature dependence of the slot-waveguide ring resonator sensors and find that they show a low temperature dependence of 16.6 pm/K, while at the same time a large refractive index sensitivity of 240 nm per refractive index unit. Furthermore, by using on-chip temperature referencing, a differential temperature sensitivity of only 0.3 pm/K is obtained, without indivvidual sensor calibration. This low value indicates good sensor-to-sensor repeatability, thus enabling use in highly parallel chemical assays. We demonstrate refractive index measurements during temperature drift and show a detection limit of 8.8×106 refractive index units in a 7 K temperature operating window, without external temperature control. Finally, we suggest the possibility of athermal slot-waveguide sensor design.

We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 [times] 10-6 refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm-2, to our knowledge the best reported values for integrated planar ring resonators.

We present an efficient and highly alignment-tolerant light coupling and distribution system for a multichannel Si3N4/SiO2 singlemode photonics sensing chip. The design of the input and output couplers and the distribution splitters is discussed. Examples of multichannel data obtained with the system are given.

Keywords: optical systems, integrated optics, sensors, waveguides

We present a procedure to reconfigure microring resonators based on liquid surface adhesion. Droplets of organic solvents were deposited over Si₃N₄/SiO₂ strip- and slot-waveguide ring resonators, and the transmission spectra were measured several hours after the evaporation of the droplets at room temperature. Our measurements show that the optical properties of the microrings are significantly modified by liquid adhered to the waveguides, persisting even 96 h after bulk evaporation. Liquid-solid interfacial forces slow down liquid evaporation at the nanoscale, enabling permanent photonic configurations. Rewriteability is achieved by removing the adhered liquid with heat.

This article describes the first demonstration of ring resonators based on vertical multiple-slot silicon nitride waveguides. The design, fabrication and measurement of multiple-slot waveguide ring resonators with several coupling distances and ring radii (70 µm, 90 µm and 110 µm) have been carried out for TE and TM polarizations at the wavelength of 1.3 µm. Quality factors of 6,100 and 16,000 have been achieved for TE and TM polarization, respectively.

Keywords: 230.7370) Waveguides, (230.0230) Optical devices, (070.5753) Resonators, (130.0130) Integrated optics, (130.3120) Integrated optics devices

Ultra thin platinum films were grown by dc magnetron sputtering on thermally oxidized Si (1 0 0) substrates. The electrical resistance of the films was monitored in situ during growth. The coalescence thickness was determined for various growth temperatures and found to increase from 1.1 nm for films grown at room temperature to 3.3 nm for films grown at 400 °C. A continuous film was formed at a thickness of 2.9 nm at room temperature and 7.5 nm at 400 °C. The room temperature electrical resistivity decreases with increased growth temperature, while the in-plain grain size and the surface roughness, measured with a scanning tunneling microscope (STM), increase. Furthermore, the temperature dependence of the film electrical resistance was explored at various stages during growth.

Keywords: fabrication, hardcopy, magnetron, own_paper, platinum, resistivity, silicon_oxide, sputtering

We demonstrate label-free molecule detection by using an integrated biosensor based on a Si₃N₄/SiO₂ slot-waveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm²) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm² for anti-BSA and BSA, respectively, limited by wavelength resolution.

Keywords: biosensor, experiment, hardcopy, kth_papers, mst_papers, own_paper, protein, resonant_sensor, ring_resonator, sabio, sabio_group_papers, silicon_nitride, silicon_oxide, slot_waveguide

High efficiency surface grating couplers for silicon nitride waveguides have been designed, fabricated, and characterized. Coupling efficiencies exceeding 60 % are reported at a wavelength of 1.31 µm, as well as angular and wavelength -3 dB tolerances of 4° and 50 nm, respectively. When the wavelength is increased from 1310 nm to 1450 nm the coupling efficiency progressively decreases but remains above 20 % at 1450 nm. The influence of the duty ratio of the grating has also been investigated: maximum coupling efficiency was obtained at 50 % duty ratio.

Keywords: grating_coupler, kth_papers, mst_papers, own_paper, sabio, sabio_group_papers, silicon_nitride, silicon_oxide

We report an experimental demonstration of an integrated biochemical sensor based on a slot-waveguide microring resonator. The microresonator is fabricated on a Si₃N₄-SiO₂ platform and operates at a wavelength of 1.3 µm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n=1.33 to 1.42. A linear shift of the resonant wavelength with increasing ambient refractive index of 212 nm/refractive index units (RIU) is observed. The sensor detects a minimal refractive index variation of 2×10^-4 RIU.

Keywords: biosensor, cavity_resonator, hardcopy, kth_papers, mst_papers, own_paper, ring_resonator, silicon_nitride, silicon_oxide, slot_waveguide, waveguide

We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks. (c)2007 American Institute of Physics

Keywords: magnetron, own_paper, resistivity, sputtering

We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of < 20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.

Keywords: experiment, kth_papers, own_paper, ring_resonator, sabio_group_papers, silicon_nitride, silicon_oxide, slot_waveguide

Keywords: hardcopy, hipims, magnetron, own_paper, solitary_waves, sputtering