"where m is a number of input ports, n is a number of output ports, C is a loss [in dB] upon entry of a light into an optical switch from an optical fiber and during travel through an optical waveguide to an active area which is a crosspoint, T is a loss [in dB] upon traversing one trench and during transmission through a section of a short optical waveguide between two crosspoints, and R is a loss" . . . .