Mode Interference in Non-Adiabatic Fiber Taper With a Long Uniform Region

An investigation of non-adiabatic fiber taper with a uniform region based on coupled mode theory is performed. The mode propagation mechanism is modeled analytically to provide insight into the interference dynamics within the taper structure. To experimentally verify the modeling result, several non-adiabatic fiber tapers with different conical region and uniform region parameters are fabricated using a Vytran GPS-3400 fusion splicer. The spectra of these fiber tapers are measured and they agree well with the spectra predicted by the proposed model.