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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 article, it was shown that a stress-induced birefringence fiber can be operated as a single-polarized single-mode fiber if absorption loss is introduced in the stress-applying regions and the refractive index of the regions is raised to a level between the effective indices of the two fundamental polarization modes.
Abstract: By a simple numerical method, it is shown that a stress-induced birefringence fiber can be operated as a single-polarized single-mode fiber if absorption loss is introduced in the stress-applying regions and the refractive index of the regions is raised to a level between the effective indices of the two fundamental polarization modes. Numerical results also show that the characteristics of this fiber are sensitive to the refractive index and the location of the stress-applying regions, but rather insensitive to the size of these regions. >
51 citations
Patent•
20 Nov 2007TL;DR: In this article, an anti-resonant reflecting optical waveguide structure is proposed to reduce optical crosstalk in an image sensor and the method of forming the same is described.
Abstract: An anti-resonant reflecting optical waveguide structure for reducing optical crosstalk in an image sensor and method of forming the same. The method includes forming a trench within a plurality of material layers and over a photo-conversion device. The trench is vertically aligned with the photo-conversion device and is filled with materials of varying refractive indices to form an anti-resonant reflecting optical waveguide structure. The anti-resonant reflecting optical waveguide structure has a core and at least two cladding structures. The cladding structure in contact with the core has a refractive index that is higher than the refractive index of the core and the refractive index of the other cladding structure. The cladding structures act as Fabry-Perot cavities for light propagating in the transverse direction, such that light entering the anti-resonant reflecting optical waveguide structure remains confined to the core. This reduces the chance of photons impinging upon neighboring photo-conversion devices.
51 citations
TL;DR: It was proved that the deposition of an overlay of higher refractive index than that of the cladding of the LPFG causes large shifts in the attenuation bands induced by the grating, and it is proved that, if the second overlay is thick enough, its behavior resembles that of an infinite layer.
Abstract: It was proved [Opt Lett30, 720 (2005) ] that the deposition of an overlay of higher refractive index than that of the cladding on a long-period fiber grating (LPFG) causes large shifts in the attenuation bands induced by the grating The result is an enhancement of the sensitivity of the LPFG to variations in the ambient and overlay refractive indices or the overlay thickness The limitation of the previous design to materials with higher refractive indices than that of the cladding of the LPFG is overcome with a five-layer model To this purpose, a first overlay of higher refractive index than that of the cladding of the LPFG will enhance the sensitivity of the device to variations in the refractive index of a second overlay of lower refractive index than that of the cladding of the LPFG Moreover, it is proved that, if the second overlay is thick enough, its behavior resembles that of an infinite layer
50 citations
TL;DR: In this paper, the authors present a systematic analytic and numerical study of the detection limit of a refractive index sensor employing a directional coupler architecture within a photonic crystal fiber (PCF), based on the coupling between the core mode and a copropagating mode of a satellite waveguide formed by a single hole of the PCF infiltrated by a high index analyte.
Abstract: We present a systematic analytic and numerical study of the detection limit of a refractive index sensor employing a directional coupler architecture within a photonic crystal fiber (PCF). The device is based on the coupling between the core mode and a copropagating mode of a satellite waveguide formed by a single hole of the PCF infiltrated by a high-index analyte. Using coupled mode theory as well as full simulations, we investigate the influence of changes in the geometrical parameters of the PCF and the analyte's refractive index on sensor performance, including sensitivity, resonance width, and detection limit. We show that regardless of the details of the sensor's implementation, the smallest detectable refractive index change is inversely proportional to the coupling length and the overlap integral of the satellite mode with the analyte, so that best performance comes at the cost of long analyte infiltration lengths. This is experimentally confirmed in our dip sensor configuration, where the lowest detection limit achievable for realistic implementation is estimated to 7 × 10-8 refractive index units (RIU) based on realistic signal to noise ratios in a commercially available PCF.
50 citations
TL;DR: In this article, a partially compensated Michelson interferometer with cube-corner reflectors was used to measure the change of refractive index of water as a function of temperature.
Abstract: A partially compensated Michelson interferometer with cube-corner reflectors was used to measure the change of refractive index of water as a function of temperature. The change of refractive index was observed almost continuously from 20 to 35 °C; the results indicate 1×10−5 as the upper limit of irregularities of the temperature dependence of the refractive index of water. Some deviation from a smooth curve was observed in the temperature region of 34.5 °C, indicating probable structure in the refractive-index-vs-temperature curve of water.
49 citations