Abstract: An optical probe includes a first region and a second region connected to have a continuous optical waveguide in which a transmission mode is a single mode. The first region connected to a tip-end surface opposed to an optical device includes a region in which a mode field diameter that is maximum at the tip-end surface is gradually decreased toward a boundary between the first region and the second region. The tip-end surface is a curved surface and has a radius of curvature set so that an advancing direction of an optical signal entering through the tip-end surface approximates in parallel to a central-axis direction of the optical waveguide.

Abstract: A measurement method of receiving an emission light output from an optical semiconductor element on an incident end surface of an optical probe, shifts a relative position between the optical semiconductor element and the optical probe on a plane surface intersecting with an optical axis of the emission light, measures an incident intensity of the emission light at several positions, and obtains an incident intensity pattern showing a relationship between a change in the relative position and the respective incident intensities.

Abstract: An optical probe receives an optical signal output from a test subject. The optical probe includes an optical waveguide composed of a core portion and a cladding portion disposed on an outer periphery of the core portion, wherein an incident surface of the optical waveguide, which receives the optical signal, is a convex spherical surface with a constant curvature radius.

Abstract: An optical probe includes a core part and a clad part arranged along an outer circumference of the core part, and has an incident surface having a radius of curvature R through which an optical signal enters. The radius of curvature R and a central half angle ? at an incident point of the optical signal on the incident surface fulfil the following formulae using a radiation angle ? of the optical signal, an effective incident radius Se of the optical signal transmitted in the core part without penetrating into the clad part on the incident surface, a refractive index n(r) of the core part at the incident point, and a refracting angle ? at the incident point: R=Se/sin(?) ?=±sin?1{[K22/(K12+K22)]1/2} where K1=n(r)×cos(?)?cos(?/2) and K2=n(r)×sin(?)?sin(?/2).

Abstract: A measurement system includes a drive device configured to drive the plurality of optical semiconductor elements, a probe unit including a plurality of optical connection devices configured to receive respective emitted lights from the plurality of optical semiconductor elements and a processing device including a plurality of photoelectric converters. Each of the optical connection devices is connected to each of the photoelectric converter, and at least some of the emitted lights received by the optical connection devices are input to the photoelectric converter. The photoelectric converter converts the input emitted lights into electric signals.

Abstract: A measurement method of receiving an emission light output from an optical semiconductor element on an incident end surface of an optical probe, shifts a relative position between the optical semiconductor element and the optical probe on a plane surface intersecting with an optical axis of the emission light, measures an incident intensity of the emission light at several positions, and obtains an incident intensity pattern showing a relationship between a change in the relative position and the respective incident intensities.

Abstract: An optical probe includes a first region and a second region connected to have a continuous optical waveguide in which a transmission mode is a single mode. The first region connected to a tip-end surface opposed to an optical device includes a region in which a mode field diameter that is maximum at the tip-end surface is gradually decreased toward a boundary between the first region and the second region. The tip-end surface is a curved surface and has a radius of curvature set so that an advancing direction of an optical signal entering through the tip-end surface approximates in parallel to a central-axis direction of the optical waveguide.

Abstract: A measurement system includes an optical probe array including the m-number of optical probe groups arranged, each including the n-number of optical probes, the m-number of optical signal selectors each corresponding one of the optical probe groups, and a control circuit configured to control the optical signal selectors. The respective optical signal selectors select and output one of optical signals output from the n-number of the optical probes of the corresponding optical probe groups. The measurement system causes the control circuit to control the optical signal selectors to repeat the selection of the optical signals until the optical signals output from all of the optical probes included in the respective optical probe groups are selected.

Abstract: An optical probe receives an optical signal output from a test subject. The optical probe includes an optical waveguide composed of a core portion and a cladding portion disposed on an outer periphery of the core portion, wherein an incident surface of the optical waveguide, which receives the optical signal, is a convex spherical surface with a constant curvature radius.

Abstract: To provide a low-cost FBG sensing device having a high reliability, suitable for high-speed measurement such as vibration measurement, able to perform a remote measurement, and simple data processing, the FBG sensing device comprising one or more light sources each outputting a light having fixed output wavelength, one or more fiber-Bragg gratings each having a reflection wavelength band having an attenuation band where the magnitude of reflection attenuates with distance from the center wavelength, the fiber-Bragg gratings reflecting the lights output from said light sources, light receiving units corresponding said fiber-Bragg gratings respectively and receiving the light reflected by the corresponding fiber-Bragg grating, wherein intensities of reflected lights each of which changes corresponding to the attenuation band that changes due to a distortion produced at each of the fiber-Bragg gratings are detected to detect the distortions.

Abstract: To provide a low-cost FBG sensing device having a high reliability, suitable for high-speed measurement such as vibration measurement, able to perform a remote measurement, and simple data processing, the FBG sensing device comprising one or more light sources each outputting a light having fixed output wavelength, one or more fiber-Bragg gratings each having a reflection wavelength band having an attenuation band where the magnitude of reflection attenuates with distance from the center wavelength, the fiber-Bragg gratings reflecting the lights output from said light sources, light receiving units corresponding said fiber-Bragg gratings respectively and receiving the light reflected by the corresponding fiber-Bragg grating, wherein intensities of reflected lights each of which changes corresponding to the attenuation band that changes due to a distortion produced at each of the fiber-Bragg gratings are detected to detect the distortions.

Abstract: In a volume phase grating, a plurality of phase gratings for causing a refractive index of a substrate having an incident surface and a launched surface facing each other to be cyclically changed between the incident surface and the launched surface are so formed as to be inclined at a specified angle to the incident surface. The volume phase grating is constructed such that an incident light is caused to be obliquely incident on the incident surface, and an angle of inclination of the phase gratings to the incident surface is set such that the incident light obliquely incident on the incident surface is refracted at the incident surface and perpendicularly incident on the phase gratings.

Abstract: An external resonator is provided with a fiber having a fiber Bragg grating for reflecting light of a specific wavelength and a ferrule which holds the above described fiber inside thereof. At least some phase gratings from among the respective phase gratings that form fiber Bragg grating are inclined relative to the optical axis of the fiber.

Abstract: In a volume phase grating, a plurality of phase gratings for causing a refractive index of a substrate having an incident surface and a launched surface facing each other to be cyclically changed between the incident surface and the launched surface are so formed as to be inclined at a specified angle to the incident surface. The volume phase grating is constructed such that an incident light is caused to be obliquely incident on the incident surface, and an angle of inclination of the phase gratings to the incident surface is set such that the incident light obliquely incident on the incident surface is refracted at the incident surface and perpendicularly incident on the phase gratings.

Abstract: A broadband ASE light source is provided which comprises an amplifying optical fiber doped with rare earth; a pumping light source and an output port both which are connected to one end of the amplifying optical fiber via a multiplexer; and a reflecting or circulating member which is connected to the other end of the amplifying optical fiber, whereby the amplifying optical fiber emits ASE light containing a first and second wavelength bands through the port. Particularly, a second pumping light source may be connected to the other end of the amplifying optical fiber via another multiplexer to widen the wavelength band to longer wavelength side. Further, using the amplifying Er-doped optical fiber with the pumping light sources having wavelength of a 980 nm band, the ASE light source can emit a flattened broadband of 1530 to 1610 nm, combining the two wavelength bands of 1530 to 1570 mn and 1570 to 1610 nm.

Abstract: A broadband ASE light source is provided which comprises an amplifying optical fiber doped with rare earth; a pumping light source and an output port both which are connected to one end of the amplifying optical fiber via a multiplexer; and a reflecting or circulating member which is connected to the other end of the amplifying optical fiber, whereby the amplifying optical fiber emits ASE light containing a first and second wavelength bands through the port. Particularly, a second pumping light source may be connected to the other end of the amplifying optical fiber via another multiplexer to widen the wavelength band to longer wavelength side. Further, using the amplifying Er-doped optical fiber with the pumping light sources having wavelength of a 980 nm band, the ASE light source can be emit a flattened broadband of 1530 to 1610 nm, combining the two wavelength bands of 1530 to 1570 mn and 1570 to 3610 nm.

Abstract: In an optical amplifier wherein pumping laser light and signal laser light are multiplexed and supplied as input to a fiber doped with a rare earth element, by decreasing the number of connected sections, loss due to the connection to the rare earth-doped fiber is decreased, thereby to improve the amplifying characteristics and to simplify the production step. a pair of fibers, each which is connected by a transmitting optical fiber 1 and a rare earth-doped fiber 4, at a connected sections, are heated and fused with each other are aligned in part length to a fused jointed portion 3 which is stretched in the vicinity of the connected section 2 on the rare earth-doped fiber side, thereby forming an optical coupler.

Abstract: A separate mount type optical coupler having composite functions in which, of a plurality of optical fibers (f.sub.1, f.sub.2 and f.sub.3) arranged side by side, adjacent fibers are fusion-welded and extended at a plurality of places so as to provide, for example, a light mixing/branch-filtering function and a branching/coupling function individually, and the fusion-welded and extended portions are separately fixedly mounted, whereby connection portions and excessive length processing are eliminated.

Abstract: An element for an optical isolator which is formed by alternately bonding together at least one flat plate-shaped Faraday rotator and two or more flat plate-shaped polarizers, the optical isolator element having an outer peripheral surface which is cut such that, when the outer peripheral surface is disposed parallel to an optical axis, incidence and emergence planes of the element are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis. The optical isolator element is accommodated in a cylindrical magnet having an inner peripheral surface of the same shape as the outer peripheral surface of the optical isolator element, thereby forming an optical isolator.

Abstract: An optical coupler having a tapered fused region produced by locally heating the periphery of a plurality of aligned optical fibers, each having a core and a cladding, so that the optical fibers fuse together at the heated part, and then drawing the resulting fused region by pulling. The length of the fused region is not longer than 10 mm. The tapered fused region may be provided in such a manner that a plurality of optical fibers are disposed to intersect each other at a predetermined angle, and the intersecting portions are locally heated so as to fuse together and then subjected to pulling. The tapered fused region may be provided at each of two or more positions.