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Step-index profile

About: Step-index profile is a research topic. Over the lifetime, 3104 publications have been published within this topic receiving 53199 citations.


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TL;DR: In this paper, a new optical fiber sensing structure is described, which is capable of refractive index detection based on surface plasmon resonance (SPR) interrogation, and the sensor simply consists of two different core diameter fibers, which are connected by thermal fusion splicing, in order to deliberately leak the transmitted light wave into the cladding layer of the sensing fiber region.
Abstract: A new optical fiber sensing structure is described, which is capable of refractive index detection based on surface plasmon resonance (SPR) interrogation. The sensor simply consists of two different core diameter fibers, which are connected by thermal fusion splicing, in order to deliberately leak the transmitted light wave into the cladding layer of the sensing fiber region. Silver film was uniformly deposited around the cladding surface for SPR excitation. Experiment to measure the SPR resonance wavelength for the refractive index ranging from 1.333 to 1.398 was carried out, by using a white light source and a spectrum analyzer. Sensor response exhibited characteristic spectrum which has a minimum in a specific wavelength for a given refractive index. Sensitivities obtained from an experimentally derived curve were 2.1×10−4 and 1.5×10−4 at refractive indices of 1.333 and 1.398, respectively. It has been demonstrated that the developed hetero-core fiber structure is one of promising techniques for remote monitoring systems as a SPR refractive index sensor.

151 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that photons may tunnel through a much greater distance when a LHM that has the same magnitudes of refractive index, relative permeability and thickness as those of the RHM (which could also be air or vacuum) is included between two semi-infinite media.
Abstract: Recent experiments give evidence of a negative refractive index at microwave frequencies in a microstructured material. This discovery may allow some unique features associated with negative- refraction materials to be observed and applied. This letter describes the calculated results for photon tunneling via evanescent fields in the presence of a layer of negative-refraction material, also known as a left-handed material (LHM) in contrast to the conventional right-handed materials (RHMs). We show that photons may tunnel through a much greater distance when a LHM that has the same magnitudes of refractive index, relative permeability, and thickness as those of the RHM (which could also be air or vacuum) is included between two semi-infinite media.

151 citations

Journal ArticleDOI
TL;DR: In this paper, a compact in reflection modal interferometer consisting of a stub of large-mode area photonic crystal fiber (PCF) spliced to standard fiber is presented.
Abstract: A compact in reflection modal interferometer consisting of a stub of large-mode area photonic crystal fiber (PCF) spliced to standard fiber is presented. In the splice, the voids of the PCF are fully collapsed allowing so coupling and recombining PCF core and cladding modes. The interferometer is highly stable over time and can be used for different applications. The measuring of refractive index in the 1.33–1.45 range with high sensitivity is demonstrated. Sensing applications based on refractive index changes are also feasible.

142 citations

Journal ArticleDOI
TL;DR: Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside.
Abstract: Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside. The sensitivity to refractive index changes is larger than in other optical microcavities as microspheres, microdisks and microrings. The outer surface where total internal reflection takes place remains always in air, enabling the measure of refractive index values higher than the refractive index of the capillary material. The fabrication of capillaries with submicron wall thickness has required the development of a specific technique. A refractometer with a response higher than 390 nm per refractive index unit is demonstrated. These sensors are readily compatible with microfluidic systems.

138 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the refractive index of InP and of liquid phase-epitaxy-grown InGaAsP layers on InP in the transparent wavelength region using a Brewster-angle method.
Abstract: We have measured the refractive index of InP and of liquid‐phase‐epitaxy–grown InGaAsP layers on InP in the transparent wavelength region using a Brewster‐angle method. The dependence of the refractive index on material composition and light wavelength has been investigated for near‐lattice‐matched samples and compared with theoretical models. We show that both an interband transition model and a single effective oscillator model can be used to calculate the refractive index if the parameters used in the calculations are chosen properly. We have also studied the variation with lattice mismatch by varying the growth temperature. We found that a lattice mismatch variation of 10−3 corresponds to a change in the refractive index of approximately 0.02 for λg=1.20 μm layer band gap at λ=1.30 μm wavelength. Finally, we have measured the refractive index of doped InP substrates and found refractive index reductions, due to doping, of up to 0.05.

137 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202318
202236
20219
202011
201913
201814