1,720,962 research outputs found
Fabrication and characterization of low-cost polarimetric fiber-optic pressure sensor
No full textPolarimetric optical fiber sensors exploit the variation in the polarization state of light transmitted from a single-mode fiber with external factor, such as pressure, temperature, etc. to estimate these physical quantities. In this paper we present the principles, fabrication and operation of a low-cost polarimetric pressure sensor that is based on the coupling between the two orthogonally polarized fundamental modes in a standard telecommunication fiber
Determination of field profiles in buffer superconducting multilayer optical planar waveguides
No full textThe effect on the propagation characteristics due to a low-index buffer layer added over a lossy superconductive leaky waveguide in a high-index substrate is related to a transition from the guided modes to the leaky one. For a guided waveguide structure, neglecting the high-index substrate, the TM mode field amplitude is more confined within the core layer and in superconducting thin film and more evanescent in the air claddings than the corresponding TE mode profile. Moreover, both the TE and TM mode profiles of the buffered waveguide leaks out more into the high-index substrate in comparison with those of the waveguide with a larger buffer thickness. This behaviour is confirmed by the fraction of the power carried by the modes along of the propagation direction
Sensitivity of traveling wave photodetectors in superconducting box-shaped plasmon-polariton optical waveguides
No full textA new, very sensitive, superconducting traveling-wave photodetector made by a modified box-shaped waveguide, which includes a high-index layer, a metallic layer, and an active superconducting layer, is studied. The light confinement regimes and the power absorption efficiency in superconducting layer can be maximized by optimizing only the waveguide geometry
Simulation of the Sensing Performance of a Plasmonic Biosensor Based on Birefringent Solid-Core Microstructured Optical Fiber
Full text linkA finite element method is used to analyze the per- formance of a microstructured optical fiber-based surface plasmon resonance sensors aimed for biomedical applications, such as the detection of blood carried species. Birefringence obtained by removing of a row of holes in a two-ring hexag- onal lattice of holes in a gold covered silica fiber leads to a relatively high sensitivity of the fiber optical response to a refractive index of the analyte surrounding the fiber. This fiber structure supports two types (I and II) of resonant modes. In these modes, there is an opposite variation of some sensing parameters with the increase of the refractive index of the analyte between 1.36 and 1.39. Thus, for a smaller value (1.36) of the refractive index of the analyte na, the resonance spectral width δλ0.5 is large for the core mode I and small for the core mode II but for a larger value (1.39) of na, δλ0.5 is small for the core mode I and large for the core mode II. Also, for na = 1.36, the amplitude sensitivity SA is small for the core mode I and large for the core mode II but for na = 1.39, SA is large for the core mode I and small for the core mode II. By adjusting the radius of the gold layer, the proposed sensor shows high spectral sensitivity Sλ and narrow δλ0.5 at the same resonance wavelength and na (1.39) where the figure of merit (FOM) is very large in comparison with the most recently published values
Sensing Performance of the Bragg Fiber- Based Plasmonic Sensors with Four Layers
No full textWe report the application of the analytical and finite element methods to the analysis of the sensing performance for the Bragg fiber-based plasmonic sensors having four layers. The advantages of an optical fiber with four (SiO2, GaP, gold, and H2O) layers are a very large value of the am- plitude sensitivity (3708.8 refractive index units (RIU)−1), large values of the loss (3091.0 dB/cm) and the power fraction P (0.36) at the loss matching point for the core mode in H2O, a small value of the full width at half maximum (19.4 nm), a smaller value (2.1 nm) of the difference Δλ between maximal amplitude sensitivity and resonant wavelengths, and a sym- metric line shape of the wavelength-dependent loss but a small spectral sensitivity (3236 nmRIU−1). A modification in the geometry of the fiber produces a significant change in the sensitivity and in the propagation parameters of the device. Thus, the advantages of another optical fiber with four layers are a very large value of spectral sensitivity ( nmRIU−1), large values of the amplitude sensitivity (2084.4 RIU−1), and the loss (3214.5 dB/cm) and the power fraction P (0.35), but the difference Δλ is large (8.6 nm) and the line shape for the wavelength dependence of the imaginary part of the effective index is asymmetri
Application of a new vector mode solver to optical fiber-based plasmonic sensors
Full text linkOur analytical method uses a linear combination of the Hankel functions H1 and H2 to represent the field in the gold region of a fiber-based plasmonic sensor. This method is applied for different structures made from three, four and five layers. When the analyte is distilled water, the difference between the resonant wavelengths calculated with the finite element method and the analytical method is very small (0.00 nm for three layers, 0.19 nm for four layers and 0.07 nm for five layers with two gold layers). The important characteristics of the Bessel and Hankel functions at the loss matching point are analyze
Power absorption efficiency in superconducting box-shaped optical waveguides
No full textA very sensitive superconducting traveling wave photodetector made of a modified box-shaped waveguide, which includes two high index layers and an active superconducting layer, is studied. The optical propagation constants and the power absorption efficiency for guided modes are determined using the finite element method; the results show that by acting only on the waveguide geometry, different confinement regimes of the light in the absorption superconducting layer can be achieved and optimize
Characterization of Er3+-doped Ti:LiNbO3 waveguides: losses, absorption spectra and near field measurements
No full textIn this paper we present some experimental results about the characterization of Er^3+-doped Ti:LiNbO_3 waveguides using nondestructive methods. We report results concerning losses, near field and absorption measurements.
Waveguide losses have been measured in the 1550 nm wavelength region through an interferometric method based on two different techniques: thermal cavity tuning and wavelength sweeping. Homogeneous absorption and emission cross sections have been calculated from
transmitted spectra. The near field measurements have been used to obtain the waveguide mode profile through a deconvolution algorithm to eliminate the
probe effect. The resulting field profile allowed to reconstruct the refractive index distribution
A high performance and low-cost polarimetric fiber-optic pressure sensor
No full textIn this paper we present the working principle, fabrication and operation of a high performance, but low-cost, polarimetric pressure sensor using standard single-mode fibers. The measurement system exploits the coupling between the two orthogonally polarized fundamental modes in a standard fiber and is based on the direct evaluation of the power variation along a predefined linear polarization. The transducer is made by few loops of fiber sandwiched between two plates and its sensitivity can be tailored by changing the number of loops and position
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