The invention relates to a method for correcting errors by de-embedding dispersion parameters of a measuring object associated with measuring gates, said parameters being measured by a vectorial network analyst comprising n measuring gates. The method includes fixing the orientation of the boom relative to gravity to approximately control the shape of an excavated ground plane. An area AR1 of the outer layer at one end face of the bridge fiber is an area that is to be optically coupled to an end face of a core of each of a plurality of pumping light inputting optical fibers, while an area AR2 of the core layer at another end face of the bridge fiber is an area that is to be optically coupled to an end face of a core of an amplification optical fiber. If a change in operating environment is detected, the security device conducts a reset-up process of an authentication code h which is confidential information, and the encrypted confidential information x.