Power attenuation coefficient and intermodal beat length in perturbed optical fibers: the role of cladding

2008 ◽  
Vol 10 (8) ◽  
pp. 085306
Author(s):  
Fouad El-Diasty ◽  
E A El-Dahshan
2014 ◽  
Vol 307 (1) ◽  
pp. H73-H79 ◽  
Author(s):  
Wei Kong ◽  
Vladimir G. Fast

Previous experiments in cultures of neonatal rat myocytes demonstrated that the shape of Cai2+ transients measured using high-affinity Ca2+-sensitive dyes may be misrepresented. The purpose of this study was to examine the role of dye affinity in Cai2+ measurements in intact adult cardiac tissue by comparing optical recordings obtained with high- and low-affinity dyes. Experiments were carried out in porcine left ventricular (LV) wedge preparations stained locally by intramural injection via microcapillaries (diameter = 150 μm) with a low-affinity Ca2+-sensitive dye Fluo-4FF or Fluo-2LA (nominal Kd, ∼7–10 μmol/l), high-affinity dye Rhod-2 ( Kd = 0.57 μmol/l), and Fluo-4 or Fluo-2MA ( Kd, ∼0.4 μmol/l); in addition, tissue was stained with transmembrane potential ( Vm)-sensitive dye RH-237. Optical recordings of Vm and Cai2+ were made using optical fibers (diameter = 325 μm) glued with the microcapillaries. The durations of Cai2+ transients measured at 50% level of recovery (CaD50) using high-affinity Fluo-4/Fluo-2MA dyes were up to ∼81% longer than those measured with low-affinity Fluo-4FF/Fluo-2LA at long pacing cycle lengths (CL). In Fluo-4/Fluo-2MA measurements at long CLs, Cai2+ transients often (∼50% of cases) exhibited slow upstroke rise and extended plateau. In Rhod-2 measurements, CaD50 was moderately longer (up to ∼35%) than in Fluo-4FF recordings, but Cai2+ transient shapes were similar. In all series of measurements, mean action potential duration values were not significantly different ( P > 0.05). The delays between Vm and Cai2+ upstrokes were comparable for low- and high-affinity dyes ( P > 0.05). In conclusion, measurements of Cai2+ transient in ventricular myocardium are strongly affected by the affinity of Ca2+ dyes. The high-affinity dyes may overestimate the duration and alter the shape of Cai2+ transients.


2002 ◽  
Vol 49 (3) ◽  
pp. 1410-1413 ◽  
Author(s):  
M.O. Zabezhailov ◽  
A.L. Tomashuk ◽  
I.V. Nikolin ◽  
K.M. Golant

2008 ◽  
Vol 39-40 ◽  
pp. 261-264 ◽  
Author(s):  
K.V. Dukel`skii ◽  
A.V. Komarov ◽  
A.V. Khokhlov ◽  
E.V. Ter-Nersesyantz ◽  
V.S. Shevandin

The conception of main role of the lattice pitch value in bend-induced short-wavelength optical losses is presented. There is shown that creation of the fiber core by substitution with seven or nineteen central elements leads to the essential expansion of spectral working range in microstructured large core optical fibers.


Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 52 ◽  
Author(s):  
Igor Ayesta ◽  
Mikel Azkune ◽  
Eneko Arrospide ◽  
Jon Arrue ◽  
María Illarramendi ◽  
...  

This paper employs the solution-doping technique for the fabrication of active polymer optical fibers (POFs), in which the dopant molecules are directly incorporated into the core of non-doped uncladded fibers. Firstly, we characterize the insertion of a solution of rhodamine B and methanol into the core of the fiber samples at different temperatures, and we show that better optical characteristics, especially in the attenuation coefficient, are achieved at lower temperatures. Moreover, we also analyze the dependence of the emission features of doped fibers on both the propagation distance and the excitation time. Some of these features and the corresponding ones reported in the literature for typical active POFs doped with the same dopant are quantitatively similar among them. This applies to the spectral location of the absorption and the emission bands, the spectral displacement with propagation distance, and the linear attenuation coefficient. The samples prepared in the way described in this work present higher photostability than typical samples reported in the literature, which are prepared in different ways.


Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 209-224
Author(s):  
Zelin Ma ◽  
Siddharth Ramachandran

AbstractWith growing interest in the spatial dimension of light, multimode fibers, which support eigenmodes with unique spatial and polarization attributes, have experienced resurgent attention. Exploiting this spatial diversity often requires robust modes during propagation, which, in realistic fibers, experience perturbations such as bends and path redirections. By isolating the effects of different perturbations an optical fiber experiences, we study the fundamental characteristics that distinguish the propagation stability of different spatial modes. Fiber perturbations can be cast in terms of the angular momentum they impart on light. Hence, the angular momentum content of eigenmodes (including their polarization states) plays a crucial role in how different modes are affected by fiber perturbations. We show that, accounting for common fiber-deployment conditions, including the more subtle effect of light’s path memory arising from geometric Pancharatnam–Berry phases, circularly polarized orbital angular momentum modes are the most stable eigenbasis for light propagation in suitably designed fibers. Aided by this stability, we show a controllable, wavelength-agnostic means of tailoring light’s phase due to its geometric phase arising from path memory effects. We expect that these findings will help inform the optimal modal basis to use in the variety of applications that envisage using higher-order modes of optical fibers.


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