Investigation of the dependence of the overall losses in glass-fiber waveguides on the coupling-in angle of the radiation

A study was made of the dependence of the overall losses in glass-fiber waveguides on the angle at which the radiation is coupled in. It was found that by selecting the coupling-in angle and monitoring the farfield radiation intensity distribution the overall losses in the steady-state mode regime can be measured. The values obtained in this case are in good agreement with the overall losses measured by a method based on the backscattering of light.