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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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Patent
George E. Berkey1
23 Jul 1998
TL;DR: In this paper, a single mode optical waveguide fiber is proposed for compensating for positive dispersion in optical telecommunications systems, which has a high refractive index center segment (5) surrounded by a plurality of alternating high (6, 10, 13) and low (low, high, low) segments.
Abstract: Disclosed is a single mode optical waveguide fiber designated for compensating for positive dispersion in optical telecommunications systems. A key characteristic of the invention is that the novel dispersion compensating waveguide, viz., a waveguide having large negative dispersion, contains no dopants, such as fluorine, which lower the refractive index of silica. A refractive index profile design which includes a high refractive index center segment (5) surrounded by a plurality of alternating high (6, 10, 13) and low refractive index segments, provides a dispersion compensation fiber which has the optical properties required for the system to be compensated without sacrificing bend resistance, increasing splicing loss, or elevating polarization mode dispersion.

15 citations

Journal ArticleDOI
TL;DR: In this paper, a liquid refractive index (RI) sensor based on resonant optical tunneling effect (ROTE) was proposed to detect the RI changes by measuring the intensity variation of transmission intensity or the wavelength shift of transmission peak.
Abstract: This paper reports the design and analysis of a liquid refractive index (RI) fiber sensor based on resonant optical tunneling effect (ROTE). The device utilizes an optical cavity formed between two angled silver-coated optical fibers to detect the RI changes by measuring the intensity variation of transmission intensity or the wavelength shift of transmission peak. The simulation results show that the intensity-based method could reach a sensitivity of 10 −7 RIU (refractive index unit) and the spectrum-based method promises a sensitivity of 81,000 nm/RIU, which are much larger than those of Fabry–Perot etalons and surface plasmon resonance sensors. With ultrahigh sensitivity, pico-litre sample volume and fiber integration, this sensor may find potential applications in biochemical analysis.

15 citations

Journal ArticleDOI
TL;DR: In this article, a high-sensitivity refractive index sensor was demonstrated near the ultraviolet (UV) wavelength region using a Si3N4-subwavelength grating (SWG) with a normal incident optical geometry.
Abstract: A high-sensitivity refractive index sensor is demonstrated for the first time, near the ultraviolet (UV) wavelength region using a Si3N4-subwavelength grating (SWG) with a normal incident optical geometry. Using the eigenmode within the Si3N4-SWG, a high sensitivity for the refractive index is expected by finite-difference time-domain calculation, without an oblique incident geometry. The proposed SWG is fabricated and the high-sensitivity refractive index sensor operating near the UV wavelength is experimentally and successfully developed. The normal transmitted intensity through the fabricated SWG varies considerably with slight changes in the refractive index. The experimental sensitivity of the SWG attained 1240 % per refractive index unit (RIU) and the sensitivity shows good agreement with the calculation. These experimental results suggest that our refractive index sensor with a normal incident geometry can measure a refractive index change of 8.06 x 10-4 RIU, if the optical detection system can measure an intensity change of 1%.

15 citations

Journal ArticleDOI
M. Medhat1, S.Y. El-Zaiat1, Saleh M Abdou1, Amr Radi1, M. F. Omar1 
TL;DR: In this paper, the effect of gamma radiation, with different doses from 0.01 to 1 MGy, on the optical parameters of both the cladding (pure silica) and the core (germanium-doped silica), of an irradiated GRIN fiber was investigated.
Abstract: Multiple-beam white-light interference fringes across an irradiated GRIN fibre, of length 2 cm and immersed in a liquid wedge interferometer that is followed by a grating spectrograph, are produced. These fringes are used to investigate the effect of gamma radiation, with different doses from 0.01 to 1 MGy, on the optical parameters of both the cladding (pure silica) and the core (germanium-doped silica) of the GRIN fibre. Optical parameters such as refractive index, refractive index difference, numerical aperture, V-number, index profile, chromatic dispersion and zero-dispersion wavelength are determined and studied. A two-term Sellmeier dispersion relation is adopted and fitted to the experimental data of the refractive index. Then, a dose-dependent Sellmeier formula is deduced to represent the effect of gamma radiation on different optical parameters.

15 citations

Journal ArticleDOI
TL;DR: Arc-discharge effects on the residual stress and refractive index in single-mode optical fibers are investigated using a previously developed three-dimensional concurrent stress-index measurement method.
Abstract: Arc-discharge effects on the residual stress and refractive index in single-mode optical fibers are investigated using a previously developed three-dimensional concurrent stress-index measurement method. Using commercial optical fibers and a commercial fusion splicer, the residual stress and refractive index perturbations caused by weak electrical arc discharges in single-mode fibers were measured. Refractive index changes greater than 10-4 and longitudinal perturbation lengths of less than 500 μm were shown to be possible. The subsequent prospects for arc-induced long-period fiber gratings are analyzed, and a typical transmission resonance is predicted to have a depth of 56 dB and a bandwidth of 0.08 nm at a wavelength of 1585 nm. The results of this investigation will be useful in modeling device performance and optimization of arc-induced long-period fiber grating fabrication.

15 citations


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