The child resistant safety plug accessory fits onto an existing male prong plug in order to insulate and protect the male prongs from producing an electrical arc with auxiliary objects when being inserted, removed, or used to transmit electricity from a female pronged plug or electrical outlet. The optical fiber includes: a core that includes a photoelastically active material; an input coupling port optically coupled to the laser source to couple the laser beam into the core of the optical fiber; and an output coupling port from which the laser light is emitted after propagating through the core. , rotating AC machines, power electronic converters and transformers as well as power grids in order to enhance electric power produced by renewable facilities. The first information of the sheet includes a value of the sheet and a serial number of the sheet. or lower, and a temperature T4 at which a glass viscosity is 104 dPa\xb7s of 1,320\xb0 C.