Liquid Core ARROW Waveguides by Atomic Layer Deposition (original) (raw)
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We demonstrate good optical quality TiO 2 thin films grown by atomic layer deposition at 120°C. The optical properties were studied using spectroscopic ellipsometry and prism coupling methods. The refractive index was 2.27, and the slab waveguide propagation loss was less than 1 dB=cm at 1:53 μm. A high quality resonant waveguide grating was fabricated using a thin TiO 2 layer on top of a SiO 2 grating.
Single-mode air-clad liquid-core waveguides on a surface energy patterned substrate
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We demonstrate a new kind of single-mode micro-optical waveguide based on a liquid core on top of solid substrate and air cladding. The liquid is held in place by surface tension and patterned surface energy on the substrate. Due to the smooth nature of the liquid/air interface down to the molecular level, low scattering losses are expected. Losses were measured to be -6.0 and -7.8 dB/cm for, respectively, 12 and 9 μm wide waveguides.
Thin solid films, 2010
In this work, we report low-loss single-mode integrated optical waveguides in the near ultra-violet and visible spectral regions with aluminum oxide (Al2O3) films using an atomic layer deposition (ALD) process. Alumina films were deposited on glass and fused silica substrates by the ALD process at substrate/chamber temperatures of 200 °C and 300 °C. Transmission spectra and waveguide measurements were performed in our alumina films with thicknesses in the range of 210 – 380 nm for the optical characterization. Those measurements allowed us to determine the optical constants (nw and kw), propagation loss, and thickness of the alumina films. The experimental results from the applied techniques show good agreement and demonstrate a low-loss optical waveguide. Our alumina thin-film waveguides is well transparent in the whole visible spectral region and also in an important region of the UV; the measured propagation loss is below 4 dB/cm down to a wavelength as short as 250 nm. The low p...
Silicon Photonics V, 2010
Integrated liquid core AntiResonant Reflecting Optical Waveguide (ARROW) are used as basic component for the realization of complex optofluidic devices. Liquid core ARROW waveguides permit to confine the light in a low refractive index liquid core, by means of two high refractive index cladding layers designed to form a high reflectivity Fabry-Perot antiresonant cavity. This arrangement allows to realize liquid core waveguides that can be very useful in optofluidic applications. We report the fabrication and the characterization different optofluidic devices based on hollow core ARROW waveguide like tuneable couplers and Mach-Zehnder interferometers. The proposed devices have been realized by silicon technology. The channels have been realized by etching the silicon wafer, while the two claddings have been deposited on both wafers by LPCVD or ALD depositions.
Thin Solid Films, 2010
In this work, we report low-loss single-mode integrated optical waveguides in the near ultra-violet and visible spectral regions with aluminum oxide (Al 2 O 3 ) films using an atomic layer deposition (ALD) process. Alumina films were deposited on glass and fused silica substrates by the ALD process at substrate/chamber temperatures of 200°C and 300°C. Transmission spectra and waveguide measurements were performed in our alumina films with thicknesses in the range of 210-380 nm for the optical characterization. Those measurements allowed us to determine the optical constants (n w and k w ), propagation loss, and thickness of the alumina films. The experimental results from the applied techniques show good agreement and demonstrate a low-loss optical waveguide. Our alumina thin-film waveguides are well transparent in the whole visible spectral region and also in an important region of the UV; the measured propagation loss is below 4 dB/cm down to a wavelength as short as 250 nm. The low propagation loss of these alumina guiding films, in particular in the near ultra-violet region which lacks materials with high optical performance, is extremely useful for several integrated optic applications.
Micro-Optics 2014, 2014
We report on variation in the refractive index of amorphous and isotropic TiO 2 thin films grown by Atomic Layer Deposition (ALD) in nano optical devices. ALD-TiO 2 films of thicknesses ≤ 200 nm exhibiting negative thermo-optic coefficient (TOC) due to decrease in refractive index with temperature, owing to inherent hydrophilic nature. While ALD-TiO 2 films with thicknesses > 200 nm show positive TOC due to the predominance of TiO 2 thickness over the very thin surface porosity region. The negative TOC of thin TiO 2 films was controlled by depositing thin ALD-Al 2 O 3 diffusion barrier films that showed impermeable behavior to block the evaporation of adsorbed water molecules on TiO 2 surfaces in thermal environments. This approach turns negative sign of TOC of TiO 2 thin films to positive one which is necessary to stabilize the central resonance peak of a guided mode resonance filter (GMRF). The ALD-TiO 2 and ALD-Al 2 O 3 bi-layer stack was modeled by VASE analysis of spectroscopic ellipsometry using Cauchy Model to extract refractive indices at various temperatures, measured at two different angle of incidence (65° and 75°), covering a wide spectral range 380 ≤ λ ≤ 1800. The temperature dependent index and density of TiO 2 films were calculated from ellipsometric measured data using Lorentz-Lorenz relation.
SPIE Proceedings, 2010
Integrated liquid core AntiResonant Reflecting Optical Waveguide (ARROW) are used as basic component for the realization of complex optofluidic devices. Liquid core ARROW waveguides permit to confine the light in a low refractive index liquid core, by means of two high refractive index cladding layers designed to form a high reflectivity Fabry-Perot antiresonant cavity. This arrangement allows to realize liquid core waveguides that can be very useful in optofluidic applications. We report the fabrication and the characterization different optofluidic devices based on hollow core ARROW waveguide like tuneable couplers and Mach-Zehnder interferometers. The proposed devices have been realized by silicon technology. The channels have been realized by etching the silicon wafer, while the two claddings have been deposited on both wafers by LPCVD or ALD depositions.
Improving solid to hollow core transmission for integrated ARROW waveguides
Optics Express, 2008
Optical sensing platforms based on anti-resonant reflecting optical waveguides (ARROWs) with hollow cores have been used for bioanalysis and atomic spectroscopy. These integrated platforms require that hollow waveguides interface with standard solid waveguides on the substrate to couple light into and out of test media. Previous designs required light at these interfaces to pass through the anti-resonant layers. We present a new ARROW design which coats the top and sides of the hollow core with only SiO 2 , allowing for high interface transmission between solid and hollow waveguides. The improvement in interface transmission with this design is demonstrated experimentally and increases from 35% to 79%. Given these parameters, higher optical throughputs are possible using single SiO 2 coatings when hollow waveguides are shorter than 5.8 mm.
Liquid Core ARROW Waveguides: A Promising Photonic Structure for Integrated Optofluidic Microsensors
Micromachines, 2016
In this paper, we introduce a liquid core antiresonant reflecting optical waveguide (ARROW) as a novel optofluidic device that can be used to create innovative and highly functional microsensors. Liquid core ARROWs, with their dual ability to guide the light and the fluids in the same microchannel, have shown great potential as an optofluidic tool for quantitative spectroscopic analysis. ARROWs feature a planar architecture and, hence, are particularly attractive for chip scale integrated system. Step by step, several improvements have been made in recent years towards the implementation of these waveguides in a complete on-chip system for highly-sensitive detection down to the single molecule level. We review applications of liquid ARROWs for fluids sensing and discuss recent results and trends in the developments and applications of liquid ARROW in biomedical and biochemical research. The results outlined show that the strong light matter interaction occurring in the optofluidic channel of an ARROW and the versatility offered by the fabrication methods makes these waveguides a very promising building block for optofluidic sensor development.