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201.
Theoretical and experimental study of differential group delay and polarization dependent loss of Bragg gratings written in birefringent fiber 总被引:3,自引:0,他引:3
Sébastien Bette Christophe Caucheteur Marc Wuilpart Patrice Mégret 《Optics Communications》2007,269(2):331-337
In this paper, we completely study the wavelength dependency of differential group delay (DGD) and polarization dependent loss (PDL) for Bragg gratings written in birefringent fibers. Based on the coupled mode theory, we present analytical expressions for the evolution with wavelength of the transmission coefficient, the DGD and the PDL. The wavelength dependencies of these evolutions on the birefringence are then discussed. Experimental results are finally presented for an apodized FBG written in a bow-tie fiber. A very good agreement between theory and experience is reported, confirming the validity of the theoretical analysis. 相似文献
202.
Optical fibers are key components in telecommunication technologies. Apart from optical specifications, optical fibers are expected to keep most of their physical properties for 10–20 years in current operating conditions. The reliability and the expected lifetime of optical links are closely related to action of the chemical environment on the silica network. However, the coating also contributes largely to the mechanical properties of the fibers.The aim of this work was to study the strength and the mechanical behavior of the silica optical fibers in an acid environment and with a permanent deformation. A container with ammonium bifluoride acid salt was plunged into hot water at different temperatures (55 and 75 °C). This emitted acid vapors which attacked the optical fibers for a period of 1–18 days. An aging study was performed on silica optical fibers with standard polyacrylate coating and with hermetic carbon coating. A dynamic two-point bending bench at different faceplate velocities (100, 200, 400 and 800 μm/s) was used. For comparison, the same dynamic measurements were also carried out on non-aged fibers.After acid vapor condensation, salt crystal deposits on the fibers were displayed using an electron scanning microscope. These crystals became visible to the naked eye from the seventh day. 相似文献
203.
This study proposes a common path interference optical system for the measurement of refractive indices and thickness of uniaxial crystal material. The measurement system comprises an accurate Mach–Zehnder laser interferometer, a single-axis rotary stepping motor, and a computer. The laser interferometer is composed of a single-frequency He–Ne laser, two-beam splitters and two reflectors. The Mach–Zehnder laser interferometer measures the optical length difference by using its linear measurement accuracy. The proposed solution procedure enables both the refractive indices and the thickness of the optical waveplate to be obtained. The proposed design differs from conventional designs in that it does not use a heterodyne modulator with a lock-in technique. It is shown that the refractive indices and thickness of the tested optical elements can be measured rapidly and accurately. 相似文献
204.
Xianqing Piao Xianmin Zhang Yuichi Mori Masayuki Koishi Akinari Nakaya Shinichiro Inoue Isao Aoki Akira Otomo Shiyoshi Yokoyama 《Journal of polymer science. Part A, Polymer chemistry》2011,49(1):47-54
Electro‐optic side‐chain polymers have been synthesized by the post‐functionalization of methacrylate isocyanate polymers with novel phenyl vinylene thiophene vinylene bridge (FTC) nonlinear optical chromophores. For this application, FTC‐based chromophores were modified in their electronic donor structure, exhibiting much larger molecular hyperpolarizabilities compared with the benchmark FTC. Of these new chromophores, absorption spectra, hyper‐Rayleigh scattering experiment, and thermal analysis were carried out to confirm availability as effective nonlinear optical units for electro‐optic side‐chain polymers. The electro‐optic coefficients (r33) of obtained polymers were investigated in the process of in situ poling by monitoring the temperature, current flow, poling field, and electro‐optic signal. Compared with the nonsubstituted analogue, benxyloxy modified FTC chromophore significantly achieved higher nonlinear optical property, exhibiting molecular hyperpolarizability at 1.9 μm of 4600 × 10?30 esu and an r33 value of 150 pm/V at the wavelength of 1.31 μm. Synthesized electro‐optic polymers showed high glass transition temperature (Tg), so that the temporal stability examination exhibited >78% of the electro‐optic intensity remaining at 85 °C over 500 h. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
205.
A carbon monolith was synthesized via a polymerization–carbonization method, styrene and divinylbenzene being adopted as precursors and dodecanol as a porogen during polymerization. The resultant monolith had bimodal porous substructure, narrowly distributed nano skeleton pores and uniform textural pores or throughpores. The carbon monolith was directly used as an extracting fiber, taking place of the coated silica fibers in commercially available solid-phase microextraction device, for the extraction of phenols followed by gas chromatography–mass spectrometry. Under the studied conditions, the calibration curves were linear from 0.5 to 50 ng mL−1 for phenol, o-nitrophenol, 2,4-dichlorophenol and p-chlorophenol. The limits of detection were between 0.04 and 0.43 ng mL−1. The recoveries of the phenols spiked in real water samples at 10 ng mL−1 were between 85% and 98% with the relative standard deviations below 10%. Compared with the commercial coated ones (e.g. PDMS, CW/DVB and DVB/CAR/PDMS), the carbon monolith-based fiber had advantages of faster extraction equilibrium and higher extraction capacity due to the superior pore connectivity and pore openness resulting from its bimodal porous substructure. 相似文献
206.
The low-pressure rf plasma of a secondary neutral mass spectrometer (e-gas SNMS) was connected with a time-of-flight (ToF)
mass spectrometer for the first time. As opposed to ToF–SIMS in e-gas SNMS, the primary ion pulse cannot be used for triggering
the flight time measurement. Therefore, an extraction pulse is used which at a defined time loads an ion package from the
beam of the post-ionised particles into the ToF spectrometer. The newly developed ToF–SNMS system is described, and first
experimental results are presented. 相似文献
207.
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209.
The doped fiber amplifier has already emerged as the indispensable potential candidate for repeaterless transmission of information processed through single mode. Therefore the fundamental modal field in the doped single-mode fiber needs to be accurately prescribed both in the pump as well as the signal to facilitate further study of their variation with distance. Based on the novel approximation of the fundamental modal field in graded-index fiber, we formulate analytical expression as regards the variation of modal intensity with radial distance from the axis of the fiber both for the pump and the signal fields and estimate such variation for step-index fiber of some typical V values as example. We find that our estimation matches excellently with the available exact results in case of both the pump and the signal and is shown to be much superior to one-parameter Gaussian approximation. In addition, our methodology involves less computation compared to the exact analysis involving cumbersome computation. 相似文献
210.
In this paper, we have proposed a new scheme to generate double-sideband (DSB) optical millimeter-wave (mm-wave) with signal carried only by optical carrier, and its transmission performance is investigated. The theoretical and numerical results show that the DSB optical mm-wave signal generated by our scheme suffers only from the fading effect, the time shift of the sidebands has little influence on its transmission performance. The signal demodulated from the harmonic photocurrent shows a clear and open eye diagram and has good performance even if the transmission distance is very close to but not just at the fading nodes. The theoretical results are in good agreement with our numerical simulation. 相似文献