Efficient Chemical Sensing by Coupled Slot SOI Waveguides

A guided-wave chemical sensor for the detection of environmental pollutants or biochemical substances has been designed. The sensor is based on an asymmetric directional coupler employing slot optical waveguides. The use of a nanometer guiding structure where optical mode is confined in a low-index region permits a very compact sensor (device area about 1200 μm2) to be realized, having the minimum detectable refractive index change as low as 10-5. Silicon-on-Insulator technology has been assumed in sensor design and a very accurate modelling procedure based on Finite Element Method and Coupled Mode Theory has been pointed out. Sensor design and optimization have allowed a very good trade-off between device length and sensitivity. Expected device sensitivity to glucose concentration change in an aqueous solution is of the order of 0.1 g/L

Efficiency of evanescent excitation and collection of spontaneous Raman scattering near high index contrast channel waveguides

info:eu-repo/semantics/publishe

Diamond Integrated Optomechanical Circuits

Diamond offers unique material advantages for the realization of micro- and nanomechanical resonators due to its high Young's modulus, compatibility with harsh environments and superior thermal properties. At the same time, the wide electronic bandgap of 5.45eV makes diamond a suitable material for integrated optics because of broadband transparency and the absence of free-carrier absorption commonly encountered in silicon photonics. Here we take advantage of both to engineer full-scale optomechanical circuits in diamond thin films. We show that polycrystalline diamond films fabricated by chemical vapour deposition provide a convenient waferscale substrate for the realization of high quality nanophotonic devices. Using free-standing nanomechanical resonators embedded in on-chip Mach-Zehnder interferometers, we demonstrate efficient optomechanical transduction via gradient optical forces. Fabricated diamond resonators reproducibly show high mechanical quality factors up to 11,200. Our low cost, wideband, carrier-free photonic circuits hold promise for all-optical sensing and optomechanical signal processing at ultra-high frequencies

An Innovative Straight Resonator Incorporating a Vertical Slot as an Efficient Bio-Chemical Sensor

A compact and integrated label-free refractometric bio-chemical sensor based on silicon-on-insulator (SOI) is proposed and comprehensively studied at the telecommunication wavelength of λ = 1550 nm. This device incorporated a three-dimensional (3D) Fabry-Perot cavity in the nano-scale regime with maximum footprint area around 470 × 473 nm2. A resonance shift (Δλres) of 5.2 nm is reported for an ultrathin (5 nm) bio-layer sensing. Besides, an improved maximum sensitivity (S = 820 nm/RIU) is also achieved for bulk refractive index change in surroundings. As a chemical sensor, very low detection limit (DL = 6.1 × 106 RIU) also can be possible to achieve by this device. All the numerical investigations and optimizations were carried out in frequency domain by a numerically efficient and rigorous full vectorial H-field based 2-D and 3-D finite element methods (FEM). A 3D-FEM code is developed and used to find out the wavelength dependencies of the resonator. Possibility of easy CMOS fabrication and integration opportunities make this structure as a prospective and efficient lab-on-chip device

Real-time label-free biosensing with integrated planar waveguide ring resonators

We review the use of planar integrated optical waveguide ring resonators for label free bio-sensing and present recent results from two European biosensor collaborations: SABIO and InTopSens. Planar waveguide ring resonators are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics and microfluidics. This enables integrated sensor arrays for compact labs-on-chip. One application of label-free sensor arrays is for point-of-care medical diagnostics. Bringing such powerful tools to the single medical practitioner is an important step towards personalized medicine, but requires addressing a number of issues: improving limit of detection, managing the influence of temperature, parallelization of the measurement for higher throughput and on-chip referencing, efficient light-coupling strategies to simplify alignment, and packaging of the optical chip and integration with microfluidics. From the SABIO project we report refractive index measurement and label-free biosensing in an 8-channel slotwaveguide ring resonator sensor array, within a compact cartridge with integrated microfluidics. The sensors show a volume sensing detection limit of 5 × 10-6 RIU and a surface sensing detection limit of 0.9 pg/mm2. From the InTopSens project we report early results on silicon-on-insulator racetrack resonators

Optical Slot-Waveguide Based Biochemical Sensors

Slot-waveguides allow light to be guided and strongly confined inside a nanometer-scale region of low refractive index. Thus stronger light-analyte interaction can be obtained as compared to that achievable by a conventional waveguide, in which the propagating beam is confined to the high-refractive-index core of the waveguide. In addition, slot-waveguides can be fabricated by employing CMOS compatible materials and technology, enabling miniaturization, integration with electronic, photonic and fluidic components in a chip, and mass production. These advantages have made the use of slot-waveguides for highly sensitive biochemical optical integrated sensors an emerging field. In this paper, recent achievements in slot-waveguide based biochemical sensing will be reviewed. These include slot-waveguide ring resonator based refractometric label-free biosensors, label-based optical sensing, and nano-opto-mechanical sensors