Characteristics of photonic crystal fibers designed with an annular core using a single material.

We propose a kind of photonic crystal fiber (PCF) designed with an annular core and fabricated using a single material. Characteristics of such fibers, including the mode field distributions of both the core and cladding modes, the effective mode area of the fundamental core mode, and the dispersion profile, are investigated using the finite element method. The coupling between the fundamental mode and an excited core mode or cladding mode is discussed in order to apply the proposed design in mode-coupling devices. Results show that such a PCF may be suitable for both optical communications and optical sensing technologies.