Patent ID: 8837037

Claim:
An optical delay device comprising: an optical path in which an input optical signal travels the same path recursively; an optical switch that switches between an output state of outputting the optical signal input to the optical path, and a non-output state of not outputting the optical signal input to the optical path; and a controller that sets the optical switch to the non-output state until a point in time when a given delay time elapses since input of the optical signal to the optical path and at the point in time when the given delay time elapses, switches the optical switch to the output state, wherein the optical path is an optical path along which the optical signal recursively travels between a plurality of reflective media, at least any one of the reflective media is a partially transmissive medium that transmits a portion of input light, and the optical switch, in the non-output state, blocks the optical signal that is from the optical path, and transmitted and output by the partially transmissive reflective medium, and in the output state, passes the optical signal that is from the optical path, and transmitted and output by the partially transmissive reflective medium.