Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Masakazu Takabayashi

Kiichi Yoshiara

Sadayuki Matsumoto

Junichiro Hoshizaki

Shigeru Matsuno

Takuya Ohira

Satoshi Nishikawa

Eitaro Ishimura

Hajime Takeya

Tateki Mitani

Mitsunobu Gotoda

Takeshi Saito

Minoru Hashimoto

Koichi Akiyama

Kazuhisa Takagi

Keisuke Matsumoto

Eiji Yagyu

Tohru Takiguchi

Yoshifumi Sasahata

Yasuhisa Shimakura

Ryosuke Namiki

Takashi Hashimoto

Fusaoki Uchikawa

Kiyohide Sakai

Kenichi Abe

Shigeki Kanamaru

Takeyuki Maegawa

Yuichiro Horiguchi

Yutaro Hamatani

Kazushi Ishii

Yutarou Hamatani

A multi-mode interferometric optical waveguide device includes: a multi-mode interferometric optical waveguide which includes a first reflective surface; a first single-mode waveguide connected to the multi-mode interferometric optical waveguide; and a second single-mode waveguide connected to the multi-mode interferometric optical waveguide and oppose the first reflective surface. Consequently, the multi-mode interferometric optical waveguide device can propagate light from the first single-mode waveguide to the second single-mode waveguide, with further reduced optical losses.

Multi-mode interferometric optical waveguide device and photonic integrated circuit

A multi-mode interference multiplexer/demultiplexer can suppress reflected return light while guiding light to a single-mode waveguide. The multi-mode interference multiplexer/demultiplexer includes a multi-mode waveguide, a first single-mode waveguide connected to a first end, a second single-mode waveguide opposing the first single-mode waveguide, a third single-mode waveguide connected to a second end, a reflecting surface opposing the third single-mode waveguide, and a fourth single-mode waveguide connected to a side end. Light entering from the second or third single-mode waveguide is reflected off the reflecting surface and forms an image at a first connection on a side end of the fourth single-mode waveguide.

Multi-mode interference multiplexer/demultiplexer and optical element using the same

A semiconductor laser according to the present invention includes an active layer, a guide layer laminated on the active layer, a diffraction grating formed along a light emission direction in the guide layer, an upper electrode provided above the guide layer, and a lower electrode provided below the active layer. The diffraction grating includes a current-injection diffraction grating and current-non-injection diffraction gratings provided both in front of and in back of the current-injection diffraction grating. Phase shifters are individually provided at a central portion of the current-injection diffraction grating and at boundaries between the current-injection diffraction grating and the current-non-injection diffraction gratings. The upper electrode is provided above the current-injection diffraction grating and is not provided above the current-non-injection diffraction gratings.

Semiconductor laser and optical integrated light source including the same

A first arm portion and a second arm portion are provided so as to have a distance therebetween greater than a distance between input ends of two output waveguides and greater than a distance between an output end of a first output portion and an output end of a second output portion, the first arm portion forming a traveling path of light from one of the two output waveguides to the first output portion through a first optical amplifier, the second arm portion forming a traveling path of light from another one of the two output waveguides to the second output portion through a second optical amplifier. The first optical amplifier and the second optical amplifier have curved portions in which the first output portion and the second output portion are curved in a direction toward each other, and the first optical amplifier and the second optical amplifier respectively output light from the output end of the first output portion and the output end of the second output portion.

Wavelength-tunable light source and wavelength-tunable light source module

A wavelength variable light source according to the present invention includes: an MMI that includes an input side and an output side, the input side connecting to one end of each of a plurality of MMI input waveguides, and the output side connecting to a plurality of MMI output waveguides, the MMI multiplexing light input from each of the MMI input waveguides and outputting the multiplexed light to each of the MMI output waveguides; a plurality of DFB-LDs connected to the other end of each of the MMI input waveguides, each of the MMI output waveguides performing a single mode oscillation at a different wavelength; and two SOAs respectively connected to two MMI output waveguides of the MMI output waveguides, and having different gains from each other.

Wavelength variable light source and wavelength variable light source module

An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a light intensity lowering section located in each of the first optical waveguides and lower light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the respective semiconductor lasers; to decrease line width of the light output by the semiconductor lasers.

Optical semiconductor device

An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.

An objective of the present invention is to provide an optical fiber sensor which has a simple configuration to enable sensitively measuring a refractive index of a measurement medium in a wide range of refractive indexes. An optical fiber sensor according to the present invention includes; an optical fiber having a core in which a short-period gratings are formed and a cladding, the optical fiber being made so that transmission loss occurs due to cladding-propagation-mode leakage at its cladding portion where the short-period gratings are formed; a light source from which light having a wavelength range of the cladding propagation mode is emitted; and a light receiving unit for receiving transmission or reflection light having passed through the cladding at the position where the short-period gratings are formed. The optical fiber sensor detects, based on the total receiving light intensity that the light receiving unit receives, the refractive index of the measurement medium contacting the cladding, in which the optical fiber is multi-mode one, and the short-period gratings have plural kinds of periods.

Optical fiber sensor

An optical fiber sensor measuring refractive index of a medium with high sensitivity in a wide range. The optical fiber sensor includes an optical fiber causing a transmission loss due to leakage in the clad propagation mode from a portion of a core and a clad where a Bragg grating is provided, a light source permitting light in a wavelength band in the clad propagation mode to enter the optical fiber, and a light-receiving section receiving the transmitted or reflected light transmitted through the core and the clad at the portion where the Bragg grating is provided. The refractive index of the medium to be measured in contact with the clad is measured according to total intensity of the light received by the light-receiving section. The Bragg grating is inclined at a predetermined angle of inclination to the vertical line vertical to the length direction of the optical fiber.

An optical fiber sensor that can detect a liquid level or detect a property of liquid with high reliability even under a frequently vibrational environment. The optical fiber sensor includes an optical fiber that includes a core having an area where a grating is formed and a clad, the optical fiber being disposed so that at least a part of the area with the grating is immersed in liquid, a light source for making light incident to the optical fiber so that a cladding mode light having a wavelength band is generated by the grating, and a light receiving unit for detecting the intensity of light which is incident from the light source to the optical fiber and transmitted through the grating.

A tunable dispersion compensator in which a heater portion can be easily constructed to reduce cost. A tunable dispersion compensator includes: an optical fiber having a grating portion; a heating unit for heating the grating portion to apply a temperature distribution to the grating portion; and a control unit for controlling the temperature distribution applied by the heating unit to control the group delay time characteristic of the grating portion. The heating unit includes: a heater including a single conductor having electrical resistors and which extends in a longitudinal direction of the grating portion over at least the entire length of the grating portion; and wirings electrically connected with the heater in respective positions along the longitudinal direction. The control unit supplies a voltage to each of the wirings.

Tunable dispersion compensator and method of manufacturing the same

A polarization dispersion compensation apparatus includes a polarization controller, a polarization beam splitter, an optical delay circuit, and a polarization beam combiner. The polarization controller controls polarization of an optical signal so that the polarization axis of the input optical signal substantially coincides with the optical axis of an optical transmission line, and the polarization beam splitter section splits the optical signal into two polarized components perpendicular to each other. The optical delay circuit section causes a difference in delay between the two polarized components, and the polarization beam combiner section combines the two polarized components output from the optical delay circuit section. Each of the polarization beam splitter section and the polarization beam combiner section includes a symmetric Mach-Zehnder interferometer having optical transmission lines in two arms, each arm including a temperature control and a birefringence portion for compensating polarization dispersion between the two polarized components.

Polarization dispersion compensating apparatus

A variable dispersion compensator includes an optical waveguide, a temperature controller. The optical waveguide has a chirped grating having a Bragg wavelength changing along the longitudinal direction of the grating. A temperature distribution T (x) is applied to a central portion of the grating, defined as a region where a distance x from an end of the grating is a range of 20 % to 80 % of total length of the grating. Temperature distribution T (x) and T (x) are applied to end portions of the grating, defined as two regions extending from respective ends of the grating to the central region, respectively. At least one of T (x) and T (x) has a distance dependence different from that of the T (x).

Variable dispersion compensator

In a polarization mode dispersion compensating apparatus for controlling polarization mode dispersion of an optical signal, a first optical monitor detects and outputs, based on an optical signal outputted from a first optical transmission line having a grating, a first detection signal indicating magnitude of waveform distortion of the first optical transmission line, and a second optical monitor detects and outputs, based on an optical signal output from a second optical transmission line having a grating, a second detection signal indicating magnitude of waveform distortion of the second optical transmission line. A calculator circuit calculates from the first and second detection signals an output signal. A controller controls a polarization controller based on the output signal from the calculator circuit.

PMD compensating apparatus for controlling polarization controller based on detection of magnitude of waveform distortion

A method of manufacturing a grating in an optical waveguide that includes a core and a cladding covering the core. The method includes scanning a laser beam along an optical axis of the optical waveguide to modulate the refractive index of the core. The core is made of a material having a refractive index that is changeable upon irradiation by radiation. In addition, in scanning the core, the irradiation range of the laser beam is controlled and the core is scanned several times. Therefore, a predetermined distribution of irradiation is obtained in a direction of the optical axis of the grating.

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Tokyo, Japan

Masakazu Takabayashi