Abstract: With the invention, it is possible to suppress losses of light for monitoring and enhances the optical confinement efficiency into an optical fiber for output over the related art. The optical path switching device 20 includes: a platform 22 housed in an enclosure 21 and mounting various types of optical components; optical fiber collimators 23, 24 as optical input means; an optical fiber collimator 25 as optical output means; a parallelogram prism 26 for switching over the optical path between the optical fiber collimators 23, 24 and 25 based on a change in its position; and light receiving elements 31, 32 for detecting a portion of the light inputted from the optical fiber collimators 23, 24 in order to monitor the light; and controls the position of the parallelogram prism 26 in accordance with the monitoring result of the light. The light receiving elements 31, 32 are arranged to detect only a portion of the light in the outer part in radial direction.

Abstract: In a delay interferometer, a Michelson delay interferometer unit is mounted on a package made of a Kovar material. The Michelson delay interferometer unit has optical components including a beam splitter which splits an optical signal, reflectors which reflect the split optical signals, and an optical phase adjusting plate which is inserted into an optical path of the optical signal, and which is used for temperature compensation. The delay interferometer includes a glass substrate on which the optical components are bonded and mounted, and an elastic member which is interposed between the delay interferometer unit configured by the optical components mounted on the glass substrate, and a bottom portion of the package.

Abstract: In a delay interferometer in which a Michelson delay interferometer unit is mounted in a package having first and second sidewall portions that are perpendicular to each other, the delay interferometer includes: a Michelson delay interferometer unit in which first interference output light obtained by processing input light that is received through an input port disposed in the first sidewall portion is output through a first output port disposed in the first sidewall portion, and second interference output light is output from a second output port disposed in the second sidewall portion; and a first optical axis shifting member which shifts an optical axis position of the first interference output light in parallel to the first sidewall portion, to cause the light to be supplied into the first output port.

Abstract: In a delay interferometer in which a Michelson delay interferometer unit is mounted in a package, the delay interferometer includes: a Michelson delay interferometer unit in which A-channel interference output light obtained by optically processing input light that is formed by splitting input light received through an input port, into A and B channels through a splitting portion is output from an A-channel first output port and an A-channel second output port disposed, and B-channel interference output light is output from a B-channel first output port and a B-channel second output port; and a first optical path length compensating member which is interposed between the A-channel interference output light or the B-channel interference output light, and the A-channel first output port or the B-channel first output port.

Abstract: In a delay interferometer in which a Michelson delay interferometer unit is mounted in a package, the delay interferometer includes a Michelson delay interferometer unit which outputs first interference output light from a first output port, the first interference output light being obtained by optically processing input light received through an input port by a beam splitter and reflectors, and which outputs second interference output light from a second output port, and the splitting portion and the beam splitter are integrally structured.

Abstract: An actuator unit 100 which moves a light reflection element 32 in a predetermined optical path-switching-position includes a mover 120 to which the light reflection element 32 is fixed, and a fixed part body 110 including an E-shaped yoke 113. When the mover 120 is located at one end in its moving range, the posture of the mover 120 is specified by magnetic attraction forces in two directions orthogonal to each other which are generated between one end portion 113a yoke 113 and an orthogonal part 113c of the E-shaped, and the mover by a permanent magnet 121 and an electromagnet 118, whereby a tilt of the mover 120 can be prevented.