Optical frequency linear chirp variable unit

摘要

A linear opto-frequency chirp amount variable apparatus using a dielectric multilayer film mirror which does not require the optical axis to be realigned each time the amount of a chirp is to be varied, comprises a pair of dielectric multilayer film mirrors ( 2 ) and ( 2 ) arranged so that their mirror surfaces ( 2 a) and ( 2 a) extends parallel, and are opposed, to each other, and a movable mirror ( 4 ) disposed in a space defined between the dielectric multilayer film mirrors ( 2 ) and ( 2 ). The movable mirror ( 4 ) is inclined so that an incident light ( 5 ) that is incident obliquely from one end ( 3 a) of the space ( 3 ) defined between the two dielectric multilayer film mirrors ( 2 ) and ( 2 ) and is then allowed to reflect on and between them a plurality of times is reflected by the movable mirror into a direction parallel to the dielectric multilayer film mirror surfaces ( 2 a) and in an incidence plane defined by the incident light ( 5 ) and a plane-normal ( 6 ) to each dielectric multilayer film mirror ( 2 ) and towards that one end ( 3 a). The movable mirror ( 4 ) is movable in a direction that is parallel to the dielectric multilayer film mirror surfaces ( 2 a) and extends in the incidence plane ( 7 ). Moving the movable mirror ( 4 ) forwards and backwards in this direction changes the amount of a chirp to be imparted to the incident light as an input light.