Abstract: An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first tr

Abstract: An optical packet network system of a ring type, capable of preventing degradation of an optical signal, can be implemented by providing a mechanism relatively simple in structure, capable of erasing light noise if the optical packet signal does not exists. In the optical packet network system made up by interconnecting respective nodes adjacent to each other, and connecting a sending source of an optical packet signal to a ring, a light noise removal function block is provided between the respective nodes adjacent to each other.

Abstract: An optical communication apparatus includes an erbium-doped optical fiber amplifier for amplifying a modulated optical signal, wherein a light which is not modulated is inputted to the erbium-doped optical fiber amplifier together with the optical signal.

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: 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: An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first tr

Abstract: An optical switch changes over transmission paths of an optical signal by a refractive index change. The optical switch has an optical waveguide layer having an optical waveguide whose output path of an optical signal branches into two, and reflection diffusing ditches which are provided in a portion outside the optical waveguide in the optical waveguide layer, wherein the portion is closed to a branch portion of the optical waveguides. The reflection diffusing ditches extend in a direction crossing a traveling direction of the optical signal.

Abstract: An optical communication apparatus includes: an erbium-doped optical fiber amplifier for amplifying a modulated optical signal, wherein a DC (direct current) light which is not modulated is inputted to the erbium-doped optical fiber amplifier together with the optical signal.

Abstract: An optical packet network system of a ring type, capable of preventing degradation of an optical signal, can be implemented by providing a mechanism relatively simple in structure, capable of erasing light noise if the optical packet signal does not exists. In the optical packet network system made up by interconnecting respective nodes adjacent to each other, and connecting a sending source of an optical packet signal to a ring, a light noise removal function block is provided between the respective nodes adjacent to each other.

Abstract: An optical switch changes over transmission paths of an optical signal by a refractive index change. The optical switch has an optical waveguide layer having an optical waveguide whose output path of an optical signal branches into two, and reflection diffusing ditches which are provided in a portion outside the optical waveguide in the optical waveguide layer, wherein the portion is closed to a branch portion of the optical waveguides. The reflection diffusing ditches extend in a direction crossing a traveling direction of the optical signal.