فهرست مطالب marzieh naddafan

This study evaluated the light transmission characteristics of a single modular fiber with a cylindrical microchannel using the FDTD method. To this end, various microchannel diameters (4-11μm) were explored. The SMF included a silica core (n=1.4) coated by a nanodiamond layer with a refractive index of 2.42. The impact of Fabry-Perot resonance was evidently detected in transmission features. At constant , the light transmission variations depended on the refractive index of the microchannel. A significant change was observed in the upon altering the microchannel refractive index. Based on the results, a microchannel-based SMF with different diameters can be employed for refractive index sensing. In the cases where the diameter of the microchannel largely differs from that of the core (8μm), the transmission variations were negligible. The numerical results are in good agreement with those reported in the microhole or microchannel experiment. The highest and lowest transmissions were recorded for the microchannel at diameters of 4 and 11μm, respectively. Comparing related experimental and numerical results show proper control of the microchannel diameter can enhance light transmission through the core-microchannel. The sensitivity of the refractive index to the microchannel diameter is a promising feature that can be exploited for developing various fiber optical devices.

Functionalized Multi-walled carbon nanotubes (f-MWCNTs) which are modified using nitric acid and sulfuric acid were evaluated to synthesize a uniform nanocomposite via application of TiO2. The f-MWCNTs-TiO2 nanocomposites have been produced via using the chemical simple two-step method. To characterize the structural analysis, scanning electron microscopy (SEM) imaging, ultraviolet-visible (UV-Vis) spectroscopy, and Raman spectroscopy were utilized. The maximum shift of D, G, and 2G-bands of f-MWCNTs were related to 20 wt. % f-MWCNTs in TiO2 nanoparticles. Moreover, an up-shift of 40 cm-1 was recorded for the MWCNTs (G’-band) for 5 wt. % f-MWCNTs. For 20 wt. % f-MWCNTs/TiO2 (G-band) nanocomposites, was determined by 4.7%. By increasing the amount of f-MWCNTs in f-MWCNs/TiO2 nanocomposite, the compressive strain was increased. Among the four bonds, the G’-band behaved differently against increasing f-MWCNTs. The shifting frequency of G-band indicates the strong interaction between f-MWCNTs and TiO2 nanoparticles. The interaction between f-MWCNTs and TiO2 nanoparticles identified by the Gruneisen parameter. Therefore, a mechanism generated for stress transfer at the interface between f-MWCNTs and TiO2 nanoparticles which is indicated in many significant increases obtained in the mechanical and acoustical properties.