A novel twin-core fiber connector has been made by using two pieces of gradient refractive index (GRIN) lenses. The coupling loss of this connector is analyzed and several impact factors, such as lens length, focusing length of the specific matching conditions are discussed. Those factors that cause more transverse displacement have much greater coupling loss sensitivity, and the system tolerance is also considered to evaluate the practicability and the fabrication technologies.
In this paper, we analyzed the mode field distributions of the seven-core fiber consisting of a central core and six symmetrically surrounding single mode cores in a common cladding by the finite element method (FEM). The excitation characteristics in the splicing process between the seven-core fibers were numerically investigated. The efficiency of the fundamental mode excited by the incident light was studied by calculating the excitation coefficients in two cases, in which a lateral offset and a rotation offset are introduced between the two fiber ends, respectively. The results show that the excitation coefficient of the fundamental mode decreases from 1.0 to 0.1816 when the lateral offset increases from 0 to 9 μm. Similarly, when the rotation offset increases gradually from 0º to 10º, the excitation coefficient of the fundamental mode in the six surrounding cores gradually and synchronously decreases from 1.0 to 0.1779, while that of the central core is always constant.