Power coupling characteristics of a single mode optical fiber with a rectangular hole

A single mode optical fiber with a rectangular hole is proposed. Power coupling characteristics of the optical fiber are analyzed and discussed using numerical method. Firstly, the coupling intensity from the fiber core to the rectangular hole is investigated in different distances between the fiber core and the rectangular hole and different refractive index of the rectangular hole. Secondly, the power complete conversion and transmission characteristics are also investigated in different distances between the fiber core and the rectangular hole and different refractive index of the rectangular hole. The results show that the coupling efficiency of the proposed optical fiber from the fiber core to the rectangular hole can nearly reach to 50%. The high coupling efficiency from the fiber core to the rectangular hole can be used to develop the high efficiency mode converters. Moreover, the results also show that the coupling efficiency is higher when the refractive index of the rectangular hole is bigger than the refractive index of the fiber core. So, the proposed optical fiber has the potential application value in high refractive index sensing.