Optical Fiber Index Taper–Theoretical Analysis and Experiment Demonstration

We discuss theoretical analysis of optical fiber taper with its refractive index gradually changing alone its propagation axis caused by photosensitivity. The numeric results for two different taper shapes in step-index fiber show that the couplings of fundamental mode to the reflected mode and to high-order modes is relatively small provided the change is gradual. The fundamental mode has the capability of excellent transmission that can adjust itself adiabatically to the refractive index change. The experiment demonstrates its effectiveness for optical interconnection with different mode-fields