Abstract: A welding method includes performing welding by emitting laser light moving in a sweeping direction relatively to a processing object onto a surface of the processing object to melt a portion of the processing object onto which the laser light is emitted, wherein the laser light includes: first laser light having a wavelength equal to or larger than 800 nm and equal to or smaller than 1200 nm; and second laser light having a wavelength equal to or smaller than 550 nm.

Abstract: A busbar includes: a plurality of members that are platy; and a welding area in which two of the members are welded, the welding area being linear and extending in a first direction, the welding area being provided approximately between both ends of at least one of the two members in the first direction.

Abstract: A welding method includes: irradiating a plurality of metal foils stacked on a first surface of a metal member in a first direction with laser light to weld the metal member and the plurality of metal foils to each other, the laser light including first laser light having a wavelength of 800 [nm] or more and 1200 [nm] or less and second laser light having a wavelength of 550 [nm] or less, a second surface of a metal foil farthest from the metal member in the first direction among the plurality of metal foils, on a side opposite to the metal member, being irradiated with the laser light.

Abstract: A metal foil welding method includes: a first step of stacking a plurality of metal foils; and a second step of welding the plurality of stacked metal foils by irradiating the plurality of metal foils with laser light having a wavelength of 400 nm or more and 500 nm or less.

Abstract: A variable group delay unit has a light multiple reflector for receiving incident light and generating output light at varied output angles depending on wavelengths, a light returning part for returning the output light to the light multiple reflector, and a slit member which is provided between the light multiple reflector and the light returning part. Only light of a necessary degree is transmitted through the slit member and is reflected to a light reflecting element. A method for designing an opening width of the slit member and a method for arranging the slit member are established.

Abstract: A variable dispersion compensator comprising: an optical incidence/output device for propagating wavelength division multiplexed light; an optical multiple reflector on which the wavelength division multiplexed light emitted from the optical incidence/output device is incident for repetitive reflections; and an optical reflection device for reflecting the wavelength division multiplexed light emitted from the optical multiple reflector toward the optical multiple reflectors, the device composed of a second lens and a reflecting element and being capable of controlling the distance from the optical multiple reflector. A temperature adjusting element and a temperature detecting element are arranged via a thermal-conductive elastic member on a surface of the optical multiple reflector at a portion where no drop occurs in the intensity of the wavelength division multiplexed light incident/emitted. The temperature of the optical multiple reflector is controlled by a controller.

Abstract: A variable group delay unit has a light multiple reflector for receiving incident light and generating output light at varied output angles depending on wavelengths, a light returning part for returning the output light to the light multiple reflector, and a slit member which is provided between the light multiple reflector and the light returning part. Only light of a necessary degree is transmitted through the slit member and is reflected to a light reflecting element. A method for designing an opening width of the slit member and a method for arranging the slit member are established.

Abstract: An optical multiplexing/demultiplexing module for inputting a first linearly polarized beam after exiting a first optical waveguide, and the first beam is collimated by a first lens. A second linearly polarized beam exits a second optical waveguide and is collimated by a second lens. Both beams enter an entrance surface of a uniaxial birefringent crystal. The second beam enters the crystal along an optical path which is changed by a prism. This reduces the distance between the respective points of entrance of the beams. The beams which have entered the crystal are multiplexed at an exit surface of the crystal. A resultant multiplexed beam is converged by a third lens to enter and exit a third optical waveguide.

Abstract: An interleaver comprises an input-output portion for receiving and outputting light, a light path shifting portion for shifting an optical path of the light, and a wavelength multiplexing-demultiplexing portion for demultiplexing the light to lights of different wavelengths or multiplexing incident lights.

Abstract: A variable dispersion compensator comprising an optical incidence/output device for propagating wavelength division multiplexed light; an optical multiple reflector on which the wavelength division multiplexed light emitted from the optical incidence/output device is incident for repetitive reflections; and an optical reflection device for reflecting the wavelength division multiplexed light emitted from the optical multiple reflector toward the optical multiple reflectors the device composed of a second lens and a reflecting element and being capable of controlling the distance from the optical multiple reflector. A temperature adjusting element and a temperature detecting element are arranged via a thermal-conductive elastic member on a surface of the optical multiple reflector at a portion where no drop occurs in the intensity of the wavelength division multiplexed light incident/emitted. The temperature of the optical multiple reflector is controlled by a controller.

Abstract: Through spacing to each other, provided are an input/output waveguide element for introducing and deriving light and a light reflecting element for reflecting light. The light introduced by the input/output waveguide element is reflected by the reflecting element and returned to the input/output waveguide element. On a path of the light, a first lens, a multiple reflecting device and a second lens are provided with a spacing to one another. A multiple reflecting device has a first interface facing to the first lens and a second interface, or a surface opposite thereto, parallel with each other. The light entered the multiple reflecting device is multiplex-reflected upon the first interface and second interface depending upon a wavelength of the light. The multiple reflecting device has a third interface as a slant surface having an angle to the first interface of greater than 90° and smaller than 180°.

Abstract: A first linearly polarized beam (14) which has exited a first optical waveguide (30) and which has been collimated by a first lens (24) and a second linearly polarized beam (16) which has exited a second optical waveguide (32) and which has been collimated by a second lens (26) enter an entrance surface (18) of a uniaxial birefringent crystal (10). The second linearly polarized beam (16) enters the uniaxial birefringent crystal (10) along an optical path which is changed by a prism (12). This reduces a separation width D which is the distance between the point of entrance of the first linearly polarized beam (14) entering the uniaxial birefringent crystal (10) and the point of entrance of the second linearly polarized beam (16) entering the uniaxial birefringent crystal (10). The first and second linearly polarized beams (14) and (16) which have entered the uniaxial birefringent crystal (10) are multiplexed at an exit surface (22) of the uniaxial birefringent crystal.