Abstract: An optical module according to an embodiment includes a first optical component and a second optical component including a multicore fiber (MCF) and a spatial joining part. The first optical component includes a first uncoupled MCF having small optical coupling between cores and a first coupled MCF having a mode field diameter (MFD) larger than a MFD of the first uncoupled MCF. The second optical component includes a second uncoupled MCF having small optical coupling between cores and a second coupled MCF having a MFD larger than a MFD of the second uncoupled MCF. In the first coupled MCF and the second coupled MCF, crosstalk is periodically produced along the length direction of an MCF, and the total of the length of the first coupled MCF and the length of the second coupled MCF is a length L in which crosstalk is suppressed.

Abstract: An apparatus includes an element to transmit a partial amount of first light guided through the M cores of a target object and second light guided through M optical waveguides, and to reflect remaining amount thereof, a first modulator to individually modulate the first light, a first detector to output a first signal based on the first light reflected by the element and the second light passing through the element, a second detector to output a second signal based on the first light passing through the element and the second light reflected by the element, an optical system configured such that the first light and the second light overlap in pairs on the first and second detectors, and a processing unit configured to output information about mode-dependent loss of the target object based on the first signal, the second signal, and information about modulation given by the first modulator.

Abstract: A gas laser according to an embodiment includes a gas serving as a laser medium, a thermal radiation source having wavelength selectivity and configured to emit excitation light for excitation of the gas by thermal radiation, and an optical resonator for causing emission light emitted from the gas in response to the excitation light to resonate.

Abstract: A radiation device or the like has a structure for selectively converting thermal energy into an electromagnetic wave. The radiation device has a conductor layer, a semiconductor layer, and a plurality of conductor disks. The plurality of conductor disks are arranged on the semiconductor layer so that the same arrangement pattern is constituted in each of a plurality of unit constituent regions each having a rectangular shape with a side of 4.5 to 5.5 ?m. The arrangement pattern of individual unit components includes nine conductor disks so as to correspond to a 3×3 matrix, and the nine conductor disks include four or more kinds of conductor disks having diameters different from each other. As a result, a two-dimensional periodic structure of the arrangement pattern is formed on the semiconductor layer.

Abstract: A multi-core fiber module includes a transmission MCF configured to be used as a transmission path for an optical signal, a connection MCF having a core arrangement similar to a core arrangement of a core of the transmission MCF, and a relay lens system interposed between the transmission MCF and the connection MCF. A relay magnification of the relay lens system is equal to a ratio of a core interval of the connection MCF to a core interval of the transmission MCF. A core at a leading end surface of the connection MCF is expanded such that a ratio between the core interval and a mode field diameter of the connection MCF is equal to a ratio between the core interval and a mode field diameter of the transmission MCF.

Abstract: An optical amplifier includes one or more rare earth element-doped optical fibers each including one or more cores, two or more excitation light sources per single core of the one or more rare earth element-doped optical fibers, configured to emit excitation light for exciting a rare earth element added to the one or more rare earth element-doped optical fibers according to a driving current, and a synthesizing part configured to synthesize the excitation light emitted from the two or more excitation light sources per single core. Two or more cores are provided in total, and the excitation light emitted from the two or more excitation light sources per single core is synthesized and input with respect to each core.

Abstract: An optical connection structure includes a first spatial multiplex transmission line, a second spatial multiplex transmission line, a first lens arrangement, a second lens arrangement and a first beam diameter conversion portion. The first spatial multiplex transmission line has a plurality of first transmission lines. The second spatial multiplex transmission line has a plurality of second transmission lines. The first lens arrangement is optically coupled with the first spatial multiplex transmission line. The second lens arrangement is optically coupled with the second spatial multiplex transmission line. The first beam diameter conversion portion has a first end face and a second end face and arranged between the first spatial multiplex transmission line and the first lens arrangement. The first beam diameter conversion portion is configured such that an optical diameter at the second end face is larger than an optical diameter at the first end face.

Abstract: An optical module according to an embodiment includes a first optical component and a second optical component including a multicore fiber (MCF) and a spatial joining part. The first optical component includes a first uncoupled MCF having small optical coupling between cores and a first coupled MCF having a mode field diameter (MFD) larger than a MFD of the first uncoupled MCF. The second optical component includes a second uncoupled MCF having small optical coupling between cores and a second coupled MCF having a MFD larger than a MFD of the second uncoupled MCF. In the first coupled MCF and the second coupled MCF, crosstalk is periodically produced along the length direction of an MCF, and the total of the length of the first coupled MCF and the length of the second coupled MCF is a length L in which crosstalk is suppressed.

Abstract: An optical fiber amplifier comprising first, second and third optical fibers, and first, second and third lenses, is disclosed. First cores of the first optical fiber and second cores of the second optical fiber have homothetic arrangement each other in the arrangement of outer cores. The first core has a mode field diameter MFD1S when transmitting an optical signal and a core pitch P1, and the first lens has a focal distance f1S at the wavelength of the optical signal. The second core has a mode field diameter MFD2S when transmitting the optical signal and a core pitch P2, and the second lens has a focal distance f2S at the wavelength. The MFD1S of each first core is within ±25% of MFD2S×(P1/P2) of the corresponding second core, and the MFD1S of each first core is within ±25% of MFD2S×(f1S/f2S) of the corresponding second core.

Abstract: An optical fiber amplifier according to one embodiment includes a multicore fiber doped with erbium, and the multicore fiber is twisted and helically wound to form a fiber coil.

Abstract: A radiation device or the like has a structure for selectively converting thermal energy into an electromagnetic wave. The radiation device has a conductor layer, a semiconductor layer, and a plurality of conductor disks. The plurality of conductor disks are arranged on the semiconductor layer so that the same arrangement pattern is constituted in each of a plurality of unit constituent regions each having a rectangular shape with a side of 4.5 to 5.5 ?m. The arrangement pattern of individual unit components includes nine conductor disks so as to correspond to a 3×3 matrix, and the nine conductor disks include four or more kinds of conductor disks having diameters different from each other. As a result, a two-dimensional periodic structure of the arrangement pattern is formed on the semiconductor layer.

Abstract: An optical amplifier according to an embodiment includes a pump laser that emits a pumping light beam, and an external resonator that is provided on the outside of the pump laser. In the inside of the external resonator, an optical waveguide that is doped with a rare earth element which absorbs the pumping light beam and that amplifies a signal light beam is disposed, and residual pumping light beams and which are emitted from the optical waveguide are confined.

Abstract: An optical connection structure includes a first spatial multiplex transmission line, a second spatial multiplex transmission line, a first lens arrangement, a second lens arrangement and a first beam diameter conversion portion. The first spatial multiplex transmission line has a plurality of first transmission lines. The second spatial multiplex transmission line has a plurality of second transmission lines. The first lens arrangement is optically coupled with the first spatial multiplex transmission line. The second lens arrangement is optically coupled with the second spatial multiplex transmission line. The first beam diameter conversion portion has a first end face and a second end face and arranged between the first spatial multiplex transmission line and the first lens arrangement. The first beam diameter conversion portion is configured such that an optical diameter at the second end face is larger than an optical diameter at the first end face.

Abstract: An optical fiber amplifier comprising first, second and third optical fibers, and first, second and third lenses, is disclosed. First cores of the first optical fiber and second cores of the second optical fiber have homothetic arrangement each other in the arrangement of outer cores. The first core has a mode field diameter MFD1S when transmitting an optical signal and a core pitch P1, and the first lens has a focal distance f1S at the wavelength of the optical signal. The second core has a mode field diameter MFD2S when transmitting the optical signal and a core pitch P2, and the second lens has a focal distance f2S at the wavelength. The MFD1S of each first core is within ±25% of MFD2S×(P1/P2) of the corresponding second core, and the MFD1S of each first core is within ±25% of MFD2S×(f1S/f2S) of the corresponding second core.

Abstract: An optical fiber sensor system includes a light source, a modulation unit, an optical coupler, a polarization separator, a first polarization controller optically coupled to the polarization separator, and a first detection unit that includes a first optical detector that receives the first component, converts the first component into a first electrical signal, and detects stress. The first polarization controller controls a polarization state of light input to the polarization separator so that the first electrical signal exhibits a first-order response to the stress.

Abstract: The optical fiber sensor system includes a light source unit including a light source and a polarization controller, a modulation unit having an optical path and a coil and configured to modulate light passing though the optical path according to stress applied to the coil, an optical coupler configured to branch the measured light into clockwise light and counterclockwise light, and output interference light, a polarization separator configured to separate the interference light into a first component and a second component having polarization states orthogonal to each other, and a detection unit having a first light detector and configured to detect stress by converting the first component into a first electrical signal. The polarization controller controls a polarization state of light output from the light source so that the first electrical signal is proportional to the stress.

Abstract: An optical fiber sensor system includes a light source, a modulation unit, an optical coupler, a polarization separator, a first polarization controller optically coupled to the polarization separator, and a first detection unit that includes a first optical detector that receives the first component, converts the first component into a first electrical signal, and detects stress. The first polarization controller controls a polarization state of light input to the polarization separator so that the first electrical signal exhibits a first-order response to the stress.

Abstract: An interferometric optical fiber sensor system comprises a light source, a first coupler optically connected to the light source, a first optical path for inputting measurement light, a second optical path for inputting reference light, a second coupler for combining the first and second optical paths together, a photodetector for measuring modulation of the measurement light and the reference light, and a coil for modulating with a stress exerted thereon the measurement light and the reference light. The first optical path has an optical length equal to that of the second optical path. The first optical path has a first delay line, while the second optical path has a second delay line. The coil is disposed between the first delay line and the second coupler and between the second delay line and the first coupler.

Abstract: In an optical path control device, a light input section 1 forms optical apertures 61a, 61b to output dispersed beams L2a, L2b, respectively, so that propagation angles of the dispersed beams L2a, L2b in an YZ plane are different from each other, at a focal position on the dispersive element 5 side of an optical power element 6. The dispersed beams L2a, L2b propagating at their respective angles different from each other in the YZ plane are individually coupled to optical deflectors 7a, 7b, respectively.

Abstract: A wavelength selective switch 1A includes a light input/output unit 10, a dispersive element 20, and a light deflection element 30 disposed side by side on a predetermined axis C. The light input/output unit 10 has a first portion 10a in which light enters and exits a light input/output port 11 by an optical axis inclined with respect to the predetermined axis C, and a second portion 10b in which light enters and exits a light input/output port 12 by an optical axis inclined with respect to the predetermined axis C. A light entry/exit angle of the light input/output port 11 with the predetermined axis C as a reference and a light entry/exit angle of the light input/output port 12 with the predetermined axis C as a reference differ from each other.