Abstract: Provided is a method of manufacturing an optical device that includes a multicore fiber including a plurality of cores and a fan-in/fan-out device including single-core fibers that are respectively connected to the cores based on a plurality of connection combinations when the multicore fiber is rotated. The method includes: a first step of determining an optical loss for each of the cores while changing the connection combinations between the single-core fibers and the cores; and a second step of selecting one of the connection combinations according to a result of the first step and connecting an end portion of the multicore fiber and an end portion of the fan-in/fan-out device to connect the single-core fibers with the cores based on the one of the connection combinations.

Abstract: Provided is a method of manufacturing an optical device that includes a multicore fiber including a plurality of cores and a fan-in/fan-out device including single-core fibers that are respectively connected to the cores based on a plurality of connection combinations when the multicore fiber is rotated. The method includes: a first step of determining an optical loss for each of the cores while changing the connection combinations between the single-core fibers and the cores; and a second step of selecting one of the connection combinations according to a result of the first step and connecting an end portion of the multicore fiber and an end portion of the fan-in/fan-out device to connect the single-core fibers with the cores based on the one of the connection combinations.

Abstract: A semiconductor device includes self-arc-extinguishing elements and a clamp circuit. Each of the self-arc-extinguishing elements has a control terminal and main electrode terminals. The clamp circuit clamps, at the time of turnoff of one of the self-arc-extinguishing elements, the voltage between the main electrode terminals of the self-arc-extinguishing element at a clamp voltage set equal to or lower than 70% of a static withstand voltage that the self-arc-extinguishing element has. The self-arc-extinguishing elements are connected in series with each other. The clamp circuit may be provided between the control terminal and the main electrode terminal of the self-arc-extinguishing elements. The clamp circuit may include a circuit formed by connecting Zener diodes in series such that an anode of one of the Zener diodes is connected to a cathode of another Zener diode.

Abstract: A multicore fiber includes: a first core configured to propagate an LP01 mode, an LP11 mode, and an LP21 mode light beam; and a second core configured to propagate an LP01 mode light beam, wherein a different mode interaction section is provided in which a propagation constant of the LP21 mode light beam propagated through the first core is matched with a propagation constant of the LP01 mode light beam propagated through the second core, a different mode non-interaction section is provided in which propagation constants of the LP mode light beams propagated through the first core are not matched with propagation constants of the LP mode light beams propagated through the second core, and the first core includes an inner core and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core.

Abstract: An optical device includes a plurality of cores and a clad that surrounds outer circumferential surfaces of the cores and has a lower refractive index than the cores. Each of the cores has a large diameter portion, a tapered portion, and a reduced diameter portion formed along a longitudinal direction and has a refractive index gradually increasing from outer circumference to a center. In each of the cores, a radial-direction distance r (?m) from the center, a refractive index n(r) at the distance r, a relative refractive index difference ?[%] of the center with respect to the clad, a radius r0 [?m], and a constant ? satisfy predetermined formulas and a wavelength ? [nm] of light propagating through the cores and a diameter R of each core before the diameter reduction with respect to a diameter of each core after the diameter reduction satisfy predetermined formulas.

Abstract: A multicore fiber includes: a center core that propagates four LP mode light beams including an LP02 mode light beam; and a first to a fifth cores disposed on a first line to a fifth line segments extend from the center of the center core in the radial direction at predetermined angles. The multicore fiber includes a different mode interaction section in which the propagation constants of each mode light beam propagated through the center core are matched with the propagation constants of LP01 mode light beams propagated through the first to fifth cores.

Abstract: An optical modulation device configured of a planar optical waveguide, includes: a light incidence unit which allows light to be incident on the planar optical waveguide; a Mach-Zehnder interferometer which includes a first optical splitter section branching the light incident on the light incidence unit, two arm portions guiding the light branched by the first optical splitter section, a phase modulation unit linearly disposed on each of the two arm portions, and a first optical coupler section combining the light guided from the two arm portions; a light launching unit which launches the light combined by the first optical coupler section from the planar optical waveguide; and a traveling-wave electrode which includes an input unit and an output unit, and applies a voltage to the phase modulation unit.

Abstract: A multicore fiber includes: a center core that propagates four LP mode light beams including an LP02 mode light beam; and a first to a fifth cores disposed on a first line to a fifth line segments extend from the center of the center core in the radial direction at predetermined angles. The multicore fiber includes a different mode interaction section in which the propagation constants of each mode light beam propagated through the center core are matched with the propagation constants of LP01 mode light beams propagated through the first to fifth cores.

Abstract: A multicore fiber includes: a first core configured to propagate an LP01 mode, an LP11 mode, and an LP21 mode light beam; and a second core configured to propagate an LP01 mode light beam, wherein a different mode interaction section is provided in which a propagation constant of the LP21 mode light beam propagated through the first core is matched with a propagation constant of the LP01 mode light beam propagated through the second core, a different mode non-interaction section is provided in which propagation constants of the LP mode light beams propagated through the first core are not matched with propagation constants of the LP mode light beams propagated through the second core, and the first core includes an inner core and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core.

Abstract: A multicore fiber 1 includes: a small diameter portion 33 in which a propagation constant of light of an x1-th order LP mode of the first core 11 (here, x1 is an integer of “2” or more and x or less, x is an integer of “2” or more) and a propagation constant of light of a y1-th order LP mode of the second core 12 (here, y1 is an integer of “1” or more and y or less other than x1, y is an integer of “1” or more) coincide with each other and a large diameter portion in which a propagation constant of light of each LP mode of the first core 11 and a propagation constant of light of each LP mode of the second core 12 are configured not to coincide with each other are arranged.

Abstract: A semiconductor device includes self-arc-extinguishing elements and a clamp circuit. Each of the self-arc-extinguishing elements has a control terminal and main electrode terminals. The clamp circuit clamps, at the time of turnoff of one of the self-arc-extinguishing elements, the voltage between the main electrode terminals of the self-arc-extinguishing element at a clamp voltage set equal to or lower than 70% of a static withstand voltage that the self-arc-extinguishing element has. The self-arc-extinguishing elements are connected in series with each other. The clamp circuit may be provided between the control terminal and the main electrode terminal of the self-arc-extinguishing elements. The clamp circuit may include a circuit formed by connecting Zener diodes in series such that an anode of one of the Zener diodes is connected to a cathode of another Zener diode.

Abstract: A switching element (A) is connected in parallel to a load (L). A switching element (B) is connected between the switching element (A) and a grounding point. The drive circuit (1) drives the switching element (A). The drive circuit (2) drives the switching element (B). Upon detecting a load short circuit, a load short circuit detection circuit (3) outputs a first signal. A timer (6) outputs a second signal after a lapse of a predetermined time after inputting the first signal. Upon receiving the first signal, the drive circuit (1) turns ON the switching element (A). Upon receiving the second signal, the drive circuit (2) turns OFF the switching element (B).

Abstract: An optical device includes: multiple cores each including an inner core and an outer core surrounding an outer circumferential surface of the inner core without any gap therebetween; and cladding surrounding an outer circumferential surface of the cores without any gap therebetween and having a refractive index lower than that of the outer core, wherein each of the cores has a tapered portion that is tapered from one side toward the other side thereof in a longitudinal direction, each of the inner cores includes a low-refractive-index portion, and a high-refractive-index portion surrounding an outer circumferential surface of the low-refractive-index portion without any gap therebetween and having a refractive index higher than that of the low-refractive-index portion, and the outer core has a refractive index lower than that of the high-refractive-index portion.

Abstract: 0.5377×r2?7.7?V2/V1?0.5377×r2?5.7, 3?r2/r1?5 are satisfied, where a radius of the inner core before tapered in diameter is defined as r1, a radius of the outer core before tapered in diameter is defined as r2, a refractive index volume formed of a product of a cross sectional area of the inner core and a relative refractive index difference of the inner core to the cladding before tapered in diameter is defined as V1, and a refractive index volume formed of a product of a cross sectional area of the outer core and a relative refractive index difference of the outer core to the cladding before tapered in diameter is defined as V2.

Abstract: 0.5377×r2?7.7?V2/V1?0.5377×r2?5.7, 3?r2/r1?5 are satisfied, where a radius of the inner core before tapered in diameter is defined as r1, a radius of the outer core before tapered in diameter is defined as r2, a refractive index volume formed of a product of a cross sectional area of the inner core and a relative refractive index difference of the inner core to the cladding before tapered in diameter is defined as V1, and a refractive index volume formed of a product of a cross sectional area of the outer core and a relative refractive index difference of the outer core to the cladding before tapered in diameter is defined as V2.

Abstract: A multicore fiber 1 includes: a small diameter portion 33 in which a propagation constant of light of an x1-th order LP mode of the first core 11 (here, x1 is an integer of “2” or more and x or less, x is an integer of “2” or more) and a propagation constant of light of a y1-th order LP mode of the second core 12 (here, y1 is an integer of “1” or more and y or less other than x1, y is an integer of “1” or more) coincide with each other and a large diameter portion in which a propagation constant of light of each LP mode of the first core 11 and a propagation constant of light of each LP mode of the second core 12 are configured not to coincide with each other are arranged.

Abstract: A switching element (A) is connected in parallel to a load (L). A switching element (B) is connected between the switching element (A) and a grounding point. The drive circuit (1) drives the switching element (A). The drive circuit (2) drives the switching element (B). Upon detecting a load short circuit, a load short circuit detection circuit (3) outputs a first signal. A timer (6) outputs a second signal after a lapse of a predetermined time after inputting the first signal. Upon receiving the first signal, the drive circuit (1) turns ON the switching element (A). Upon receiving the second signal, the drive circuit (2) turns OFF the switching element (B).