Study Of The Electric Field And Energy Characteristics Of Tapered Fiber

Fiber end face can be made into different shapes by modern grinding process. Due to total internalreflection, evanescent waves would appear at the interface between core and cladding. The transmissioncharacteristics could be greatly impacted by intensity distribution of evanescent field electric field at thefiber end face. In order to explore the electric field distribution and energy characteristics of taperedmicro/nano fiber, a numerical simulation is completed in COMSOL.This paper mainly illustrates end face of fibers in tow shapes, tapered fiber andwedge-shaped fiber. The electric field distribution and energy distribution of formula aboutoptical fiber is obtained according to Maxwell equations combining with finite elementmethod. Settings of equations and parameters in RF module in COMSOL mutiphyscis isanalyzed in details.For single conical shape micro/nano fiber and wedge-shaped micro/nano fiber, it isshowed that the electric field intensity distribution or energy distribution mainly concentratedin the core section, besides, as the transmission distance increases, part of energy would leakfrom the core, most of which is bound in the surface of the fiber core when the incidentwavelength is meeting the single-mode transmission. In a single conical micro/nano fiber, theenergy density on axis changes exponentially as the cone end radius changes. When the coneend radius is less than1/10of the incident wavelength,the transmission of energy in the coreis almost zero.Through the axial and radial movement to change the size of the micro/nano fibercoupling region, it found that transmission efficiency in conical micro/nano fiber increases asthe coupling region becomes larger at cost of reduction the coupling efficiency when conicalmicro/nano fiber couples with micro/nano fibers. When the micro/nano fiber is closed to theconical micro/nano fiber, coupling transmission is dominant then, meaning that the energytransferred to the micro/nano fibers is greater than that in the conical optical fiber. In a certainsize at the coupling region, for example, r=0.1μm, when the axial displacement of a is longerthan1.65μm, the transmission efficiency is greater than the coupling efficiency, and also r=0.2μm, when the axial displacement of a>0.64μm.When the two wedge-shaped micro/nano fiber is coupling, through the root of the axialand radial movement of the second wedge shape micro/nano fiber to change the couplingregion size. The Fresnel reflection occurs at the end face of the wedge shape fiber wouldproduce a weak influence on the coupling efficiency, it was slightly lower than not calculatedof The Fresnel reflection. The coupling efficiency presented a slow downward trend whenincrease axial displacement, and if we slightly change radial displacement, the couplingefficeency is change a lot. When the wedge angle increases from small, the couplingefficiency decreases and then rises, The coupling efficiency is very large, or almost close to 99.9%, when the wedge angle is10to100. Then the wedge angle of100to500, the couplingefficiency decreased at a faster rate, then began to rise.Through detailed numerical analysis of the tapered fiber will broaden its applications infiber optic coupler,fiber optic switches, fiber optic sensors,semiconductor lasers.