The research was conducted with both mathematical calculations and experimental measurements. In the experimental part XYZ positioner was used to examine loss for longitudinal and lateral displacement of optical fibre connection. The authors used both single-mode (9/125μm) and multimode (50/125μm) fibers, all experiments were conducted at two light wavelengths, λ = 1310nm and λ = 1550nm. Theoretical calculations were carried out at a light wavelength λ = 1310nm.