Mode‐field‐diameter measurement method using a field mask

Abstract

AbstractIn the mask method, which is one of the measurement procedures of estimation of the mode field size of single mode optical fibers, measurement setup can easily be devised. the advantage is that the overall system is small in size. However, there are few investigations with only a few reports on the physical properties of the field mask required in realization of the measurement method or the details of applications to the dispersion shifted optical fibers used in trunk lines. the present paper investigates the required physical characteristics of the mask and it is found that in order to keep the error in the measurement of the mode field radius below, the mask attenuation must be larger than 45 dB. Further, when the required attenuation is not satisfied by the mask, the equation under which there is still the possibility of field measurement is derived. Using the derived equation, it became clear that it is possible to measure the mode field radius of the 1.3 μm band and the dispersion shifted fibers by the far field method with deviations below 1 percent. Further, when such a method is devised to fit into the far end of the fiber cables, their mode field radius can be measured when the maximum cable loss is 45 dB.