Optical Field Distributions In Optical Fibers Of Taper And Connection With Different Refractive Index By FD-BPM

In the 20th century, optical fiber is carried out to office and home in many developed countries. Fiber optic is the basic deliver physical medium in optic communication system, so it is very important to study optical distribution in optical fiber.The basic structure and classification of fiber optic is studied first. The spread, loss and color dissemination characteristics of light are analyzed. The development of BPM is studied. A few BPM methods are analyzed and compared. We carried on a simple summary to a few boundary conditions, then introduced the mode theories on optical fiber.This text is on the base of understanding BPM theories on wave equation, finite difference scheme of slowly-varying envelope approximation BPM and wide-angle BPM was educed in two-dimensional and three-dimensional. It is the most important to get the finite difference scheme of optical transmission in optical fiber and tapered optical fiber with FD-BPM on Helmholtz equation according to the axle light rays equation with slowly-varying envelope approximation and circular symmetry of waveguide.We constructed the programs of the optical fiber, the tapered optical fiber and optical fiber connecting using Matlab, simulated the light field distribution of nine basic models of optical fiber, the tapered optical fiber and optical fiber connecting with step, parabolic and triangle index, analyzed the spread condition and got the influence factor of energy exhaust for research of the spread characteristic and energy loss.It is hard to have accurate analytic solution for many practical optical waveguide devices. So it becomes more and more important that the accurate numerical simulation is the theory of devices design. The right optical field can be got by FD-BPM and it is the basic theory to study the spread characteristic and energy loss of optical fiber in different refractive index distributions.