A switch for controlling the transmission of light from a first optical fiber to at least a second optical fiber or from a single bidirectional optical fiber back to itself includes a housing having a spherical concave reflector mounted therewithin. Fiber mounting means is provided for mounting optical fiber(s) at a predetermined location within the housing such that at least a portion of a beam of light emanating from the end face of one fiber propagates along an incidence path toward the reflector from which it is reflected by the curved concave reflector along a predetermined reflectance path. A light interrupter is mounted within the housing for switchable movement between a light transmissive state and a light interruptive state. A light absorbing member is positioned such that residual light reflected from the light interrupter is directed toward and absorbed by the light absorbing member. A switch presence indicator for providing an indication that the light interrupter is disposed in the interdiction position may also be included.