Evanescent Field Enhancement in Liquid Crystal Optical Fibers: A Field Characteristics Based Analysis

Abstract

The paper presents the analysis of the electromagnetic wave propagation through liquid crystal optical fibers (LCOFs) of two different types-conventional guides loaded with liquid crystals (addressed as LCOFs) and those with additional twists due to conducting helical windings (addressed as HCLCOFs). More precisely, the three-layer optical waveguide structures are considered along with its outermost region being loaded with radially anisotropic liquid crystal material and the inner regions being made of usual silica, as used in conventional optical fibers. In addition to that, LCOF with twists introduced in the form of conducting helical windings at the interface of the silica core and the liquid crystal clad is also taken into account. Emphasis has been put on the power confinements by the lower-order TE modes sustained in the different sections of the LCOF structure. The results demonstrate useful applications of these guides in integrated optics as the power sustained in the liquid crystal section by the excited TE modes remains very high. In the case of twisted clad liquid crystal guides, descriptions are limited to the nature of dispersion relation only under the TE mode excitation, and corresponding to the cases of helix orientations being parallel and perpendicular to the optical axis.

On the sustainment of optical power in twisted clad dielectric cylindrical fibers

“…[1][2][3][4][5] There are several forms of complex waveguides wherein the complexities may appear either in the geometry or the materials which they are constructed of. As the transmission properties of optical waveguides essentially depend on the cross-sectional geometry [6,7] and the nature of materials [8][9][10] in the guide, lightwave propagation through varieties of guides (with varying cross-sections as well as materials that include metamaterials [11][12][13]) has been greatly dealt with in the literature. The relevant study constitutes a forefront research area of complex mediums.…”

Introductory Chapter: Whither Liquid Crystals?

“…Optical fibers with radially anisotropic liquid crystals have been greatly dealt with in the literature [24][25][26]. These have been much attractive owing to the fairly high optical anisotropic properties of liquid crystals-the feature that attracted the R&D community to introduce varieties of liquid crystal-based optical fibers in respect of geometry as well as material distributions.…”

“…These have been much attractive owing to the fairly high optical anisotropic properties of liquid crystals-the feature that attracted the R&D community to introduce varieties of liquid crystal-based optical fibers in respect of geometry as well as material distributions. These include fibers of circular [25] and elliptical [26] cross-sections, and also, those with the loading of conducting helical structures, in order to achieve control over the dispersion characteristics [27][28][29]. It has been reported before that the radially anisotropic kind of nematic liquid crystal-loaded fibers become highly sensitive, and would be of potential for evanescent wave-based sensing applications [24,25].…”

“…These include fibers of circular [25] and elliptical [26] cross-sections, and also, those with the loading of conducting helical structures, in order to achieve control over the dispersion characteristics [27][28][29]. It has been reported before that the radially anisotropic kind of nematic liquid crystal-loaded fibers become highly sensitive, and would be of potential for evanescent wave-based sensing applications [24,25]. Indeed, the use of such fibers in chemical sensors would be one of the great avenues that liquid crystal mediums open up.…”

Effects on the Energy Flux Density Due to Pitch in Twisted Clad Optical Fibers

“…During the last couple of decades, considerable amount of investigations have been reported, by taking into account varieties of guides with different structures and compositions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Within the context, twisted clad optical fiber is of special type in which the fiber core is bounded with conducting helical windings [18][19][20].…”