Search results for "Length"
showing 10 items of 2188 documents
Highly-sensitive anisotropic porous silicon based optical sensors
2012
The modeling, fabrication and characterization of PSi fabricated from both (110) and (100) surface oriented silicon for optical sensing is thoroughly reported. First, based on the generalized Bruggeman method, the birefringence and sensitivity of the fabricated membranes were calculated as a function of the fabrication parameters such as porosity and pore sizes; and external effects, such as the pores surface oxidation. Thereafter we report on the fabrication of PSi membranes from (110) and (100) surface oriented silicon with pore sizes in the range of 50 - 80 nm, and the characterization of their birefringence using a polarimetric setup. Their sensitivities were determined by filling the p…
Polarization Modulation Instability in Dispersion-Engineered Photonic Crystal Fibers
2021
Generation of widely spaced polarization modulation instability (PMI) sidebands in a wide collection of photonic crystal fibers (PCF), including liquid-filled PCFs, is reported. The contribution of chromatic dispersion and birefringence to the net linear phase mismatch of PMI is investigated in all-normal dispersion PCFs and in PCFs with one (or two) zero dispersion wavelengths. Large frequency shift sidebands are demonstrated experimentally. Suitable fabrication parameters for air-filled and liquid-filled PCFs are proposed as guidelines for the development of dual-wavelength light sources based on PMI.
High efficiency frequency doubling in fully diced LiNbO3ridge waveguides on silicon
2016
Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only the use of a precision dicing machine without the need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. The influence of the geometrical non uniformities of waveguides due to fabrication processes is asserted. Characteristics of the components are studied; notably their robustness and tunability versus temperature.
An Example of Ti:LiNbO3 Device Fabrication: The Mach-Zehnder Electrooptical Modulator
1994
Integrated optics on LiNbO3 has already reached a stage of maturity. Several manufacturers are producing standard and custom devices on LiNbO3 such as high speed (up to 20 GHz) phase and intensity modulators, switching matrices, hybrid optical gyroscopes, etc.1. Two techniques are commonly used to fabricate these devices: titanium indiffusion for 1.3 and 1.5 μm wavelength operation and annealed proton exchange (APE) at 0.8 μm, due to its higher power handling capacity.
Microreflectivity studies of wavelength control in oxidised AlGaAs microcavities
2003
Wet oxidation of GaAs/AlGaAs structures is an important technique in the processing of advanced devices such as vertical cavity surface emitting lasers (VCSELs). In one VCSEL application, the low-index and electrically-insulating AlxOy layers have been used to obtain high-reflectivity and broad bandwidth distributed Bragg reflector mirrors (DBRs). A further recent development has shown that combined lateral–vertical oxidation of intracavity AlGaAs layers can be used to tune the resonant wavelength of a semiconductor microcavity. The slow oxidation rate limits the lateral scale of practical wet oxidation to mesas structures of 50–100 μm in width. Therefore post-processing assessment of spect…
In-line fiber-optic sensors based on the excitation of surface plasma modes in metal-coated tapered fibers
2001
Abstract Metal-coated tapered fibers are reported as refractive index sensors based on the resonant excitation of surface plasma modes supported by the metal coating. The devices are easy to fabricate and constitute an alternative to metal-coated side-polished fibers and to other sensors made up of bulk components. We report the fabrication and power transmission properties of quasi-circular devices and asymmetric devices. Both sets of devices can be operated as wavelength output sensors, as well as amplitude output sensors. The transmittance of quasi-circular devices is polarization independent and it changes more than 30 dB as a function of external refractive index.
CMOS-compatible nanoscale gas-sensor based on field effect
2009
The integration of a solid state gas sensor of the metal oxide sensor type into CMOS technology still is a challenge because of the high temperatures during metal oxide annealing and sensor operation that do not comply with silicon device stability. In the presence of an external electric field sensor sensitivity can be controlled through a change of the Fermi energy level and consequently it is possible to reduce the operation temperature. Based in this effect, a novel field effect gas sensor was developed resembling a reversed insulated : gate field effect transistor (IGFET) with the thickness of gas sensing layer in the range of the Debye length (L D ). Under these conditions the control…
Localization of non-specific X-linked mental retardation gene (MRX73) to Xp22.2.
2001
Clinical and molecular studies are reported on a family (MRX73) of five males with non-specific X-linked mental retardation (XLMR). A total of 33 microsatellite and RFLP markers was typed. The gene for this XLMR condition was been linked to DXS1195, with a lod score of 2.36 at theta = 0. The haplotype and multipoint linkage analyses suggest localization of the MRX73 locus to an interval of 2 cM defined by markers DXS8019 and DXS365, in Xp22.2. This interval contains the gene of Coffin-Lowry syndrome (RSK2), where a missense mutation has been associated with a form of non-specific mental retardation. Therefore, a search for RSK2 mutations was performed in the MRX73 family, but no causal muta…
A PCR-RFLP assay for the distinction between Fasciola hepatica and Fasciola gigantica.
2002
Fascioliasis is of well-known veterinary importance and an increasing human health problem, with reported cases in the five continents. The causative agents, Fasciola hepatica and Fasciola gigantica, present geographical distributions, which overlap in many regions of Africa and Asia, and in which the differentiation of both species is usually difficult because of the many variations in their morphological characteristics. Moreover, in humans, liver fluke classification cannot be achieved by clinical, pathological, coprological or immunological methods. The differential diagnosis between F. hepatica and F. gigantica infection is very important because of their different transmission and epi…
The Length of Leukocyte and Femoral Artery Telomeres in Patients with Peripheral Atherosclerosis.
2022
The length of telomeres (TLs) that protect chromosome ends may reflect the age of cells as well as the degree of genetic material damage caused by external factors. Since leukocyte telomere length is associated with cardiovascular diseases, the aim of this study was to evaluate whether leukocyte TL reflects femoral artery wall telomeres of patients with atherosclerosis and lower limb ischemia. Samples of femoral artery wall and blood were collected from 32 patients qualified to surgical revascularization. The analysis included blood and artery wall telomere length measurement and biochemical parameters. The study indicated that there was a moderate correlation between artery wall TL and leu…