Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
87 records were found.
Integrated optical techniques offer the potential for miniature, low-cost, reliable microsystems for chemical analysis which may be exploited in monitoring environmental pollution, food contamination, state of health, and threats to security. Some approaches towards providing flexible multisensor platforms for a wide variety of chemical and biochemical species will be presented.
Simple planar waveguides are well established components for the optical interrogation of chemical processes at surfaces, with total internal reflection fluorescence (TIRF) elements having a long pedigree and surface plasmon resonance (SPR) sensors finding widespread use in biomolecular research, for example.
Key attributes of these devices are that the optical fields are confined to a submicrometer region above the solid surface of the transducer and that the light is delivered to the surface in a well-controlled way without passing through the bulk of the sample.
Planar optical waveguides may be used for the sensitive rcal-timc interrogation of the optical properties of very thin films attached at surfaces, and microfabrication allows the definition of integrated optical circuits, including electrodes, for sensor arrays. Sensing techniques based upon thin-film absorption and rehctive index changes are presented, including electrochemically-controlled surface reactions, and present work on fluoroimmunosensor arrays and instrumentation are discussed. In particular, integrated optical immunoprobes for environmental analysis are described.
The motivation, progress and potential of optical waveguide integration into microsystems for bioanalysis will be discussed.
Planar processing technology enables great complexity at low cost for electronic systems and now has the potential to provide a revolution in mass-manufacture for all-optical systems. For this to be realised, new materials and fabrication processes suitable for advanced photonic applications must be devised. Silica is ideal for many photonics applications but its small nonlinearity, low refractive index, poor rare-earth solubility and limited IR transmission precludes its application to high-density all-optical circuits or new wavelength windows. Silicon has exhibited remarkable performance for compact linear and nonlinear optical devices and while waveguiding in silicon is attractive at wavelengths beyond 1.1μm, the recent use of Si3N4 for optical parametric oscillators [J.S. Levy et al., Nat. Photon., 4, 37-40 (2010)] has emphasised ...
Guided-wave optical biosensors have great potential for use in the field of environmental monitoring. In particular, planar waveguide technologies offer the possibility of producing compact, monolithic, multisensor devices which may be connected to instrumentation using optical fibres, allowing remote operation. Optical evanescent field sensing techniques presently under investigation include grating couplers, waveguide interferometers and surface plasmon resonance (SPR) sensors. In the latter case, the surface plasmon is generally excited using a "bulk" optical component such as a prism, and equipment using this technique is now commercially available. One potential advantage of the SPR technique is that the metal film which supports the surface plasmon may also be used as an electrode for electrochemical control of sensing reactions....
Recent research into optical fibre and waveguide amplifiers has been characterised by steady but unrevolutionary progress. Advances in the 1.5µm telecommunications window include erbium doped materials with flatter gain spectra, and planar amplifiers in a broad range of materials. At 1.3µm, substantial improvements in praseodymium doped fluoride fibre amplifiers have been witnessed and chalcogenide glasses have shown promise for enhanced gain efficiency.
Guided-wave optical biosensors have great potential for use in the field of environmental monitoring. In particular, planar waveguide technologies offer the possibility of producing compact, monolithic, multisensor devices which may be connected to instrumentation using optical fibres, allowing remote operation. Optical evanescent field sensing techniques presently under investigation include grating couplers, waveguide interferometers and surface plasmon resonance (SPR) sensors. In the latter case, the surface plasmon is generally excited using a "bulk" optical component such as a prism, and equipment using this technique is now commercially available. One potential advantage of the SPR technique is that the metal film which supports the surface plasmon may also be used as an electrode for electrochemical control of sensing reactions....
Greater integration of optical devices is required in microfluidic systems for on-chip functionality, with lenses being key components. In this paper several candidate lens types are compared and simulations are presented which show that the paraxial kinoform lens offers optimum performance for efficiency and compactness in weak guiding systems.
Rare-earth-doped multiple-cavity waveguide lasers driven by on-chip phase modulators comprise a new class of integrated optical sources. In this paper, a transfer matrix model suitable for the analysis of multiple-cavity resonators is developed and used to investigate the spectral characteristics of a resonator incorporating a Y-junction. This resonator is shown to be suitable for the realization of monolithically integrated Q-switched, line-narrowed. and tunable planar waveguide lasers.
