Abstract: A wavelength tunable laser includes a first facet including a high reflection coating film; a gain region disposed adjacent to the first facet, the gain region including two or more light emitting devices that are arranged parallel to one another; an optical wavelength multiplexer optically connected to the light emitting devices; and an optical reflector disposed adjacent to a second facet opposite the first facet, the optical reflector having a reflection spectrum with periodic reflection peaks. The optical wavelength multiplexer is disposed between the gain region and the optical reflector, and the optical reflector and the first facet including the high reflection coating film form a laser cavity.

Abstract: A wavelength tunable laser according to the present invention includes a first facet and a second facet opposite the first facet, a reflective region provided adjacent to the second facet, and a gain region provided between the first facet and the reflective region. The reflective region has a plurality of reflection peak wavelengths that periodically vary at a predetermined wavelength interval. The first facet and the reflective region constitute a laser cavity. Furthermore, the gain region includes an active layer where light is generated, a diffraction grating layer having a diffraction grating whose grating pitch varies in a light propagation direction, a refractive-index control layer provided between the active layer and the diffraction grating layer, a first electrode for injecting current into the active layer, and a plurality of second electrodes arranged in the light propagation direction to inject current into the refractive-index control layer.

Abstract: A semiconductor laser device includes a laser diode provided on a semiconductor substrate, the laser diode including a first optical waveguide having a gain waveguide, a plurality of photodiodes, a first wavelength-selective filter having periodic transmission peaks, and a second wavelength-selective filter having periodic transmission peaks, the period of the transmission peaks of the second wavelength-selective filter being different from the period of the transmission peaks of the first wavelength-selective filter. Furthermore, two photodiodes among the plurality of photodiodes are optically coupled to the first optical waveguide through the first and second wavelength-selective filters, respectively.

Abstract: A semiconductor laser includes a semiconductor laser region and a wavelength-monitoring region. The semiconductor laser region includes a first optical waveguide that includes a gain waveguide, the first optical waveguide having one end and another end opposite the one end. The wavelength-monitoring region includes a second optical waveguide that is optically coupled to the first optical waveguide with the one end therebetween, and a photodiode structure that is optically coupled to the second optical waveguide. In the wavelength-monitoring region, the second optical waveguide is branched into three or more optical waveguides, and at least two optical waveguides among the three or more optical waveguides form first ring resonators having optical path lengths different from each other.

Abstract: A semiconductor laser according to the present invention includes a first reflective region and a second reflective region disposed opposite to the first reflective region in a predetermined direction of an optical axis. The first reflective region has a plurality of gain waveguides each including an active layer and a plurality of refractive-index controlling waveguides each having a first diffraction grating formed therein. The gain waveguides and the refractive-index controlling waveguides are alternately arranged at a predetermined pitch in the direction of the optical axis. The second reflective region has a second diffraction grating.

Abstract: A semiconductor integrated optical device includes a group III-V compound semiconductor substrate, a semiconductor optical device region, and an optical waveguide region. The semiconductor optical device region and the optical waveguide region are arranged on the group III-V compound semiconductor substrate. The semiconductor optical device region has a first optical waveguide made of group III-V compound semiconductor. The optical waveguide region has a second optical waveguide optically coupled with the first optical waveguide. The optical waveguide region further includes a silicon oxide layer. The silicon oxide layer is disposed between the group III-V compound semiconductor substrate and the second optical waveguide. The second optical waveguide is made of semiconductor which is different from the group III-V compound semiconductor.

Abstract: A wavelength tunable laser according to the present invention includes a first facet and a second facet opposite the first facet, a reflective region provided adjacent to the second facet, and a gain region provided between the first facet and the reflective region. The reflective region has a plurality of reflection peak wavelengths that periodically vary at a predetermined wavelength interval. The first facet and the reflective region constitute a laser cavity. Furthermore, the gain region includes an active layer where light is generated, a diffraction grating layer having a diffraction grating whose grating pitch varies in a light propagation direction, a refractive-index control layer provided between the active layer and the diffraction grating layer, a first electrode for injecting current into the active layer, and a plurality of second electrodes arranged in the light propagation direction to inject current into the refractive-index control layer.

Abstract: A wavelength tunable laser includes a first facet including a high reflection coating film; a gain region disposed adjacent to the first facet, the gain region including two or more light emitting devices that are arranged parallel to one another; an optical wavelength multiplexer optically connected to the light emitting devices; and an optical reflector disposed adjacent to a second facet opposite the first facet, the optical reflector having a reflection spectrum with periodic reflection peaks. The optical wavelength multiplexer is disposed between the gain region and the optical reflector, and the optical reflector and the first facet including the high reflection coating film form a laser cavity.

Abstract: The present invention is to provide a method for producing a semiconductor laser diode (LD) with an enhanced ESD resistance. The method includes a step for forming an aluminum film on a facet of the LD and a step for forming an aluminum oxide film on the aluminum film. The underlying aluminum film is oxidized during the formation of the aluminum oxide film to form a double aluminum oxide layer. The ratio of the oxide composition of the underlying aluminum oxide film is smaller than that of the upper aluminum oxide film.

Abstract: The present invention is to provide a method for producing a semiconductor laser diode (LD) with an enhanced ESD resistance. The method includes a step for forming an aluminum film on a facet of the LD and a step for forming an aluminum oxide film on the aluminum film. The underlying aluminum film is oxidized during the formation of the aluminum oxide film to form a double aluminum oxide layer. The ratio of the oxide composition of the underlying aluminum oxide film is smaller than that of the upper aluminum oxide film.

Abstract: A method of manufacturing an optical waveguide device that is capable of reducing the imbalance in the refractive index profile of a core, and an optical waveguide device that has the reduced imbalance in the refractive index profile are provided. The method of manufacturing an optical waveguide device has the steps of forming a groove in a first cladding layer having a first dopant that lowers the refractive index of the first cladding layer below the refractive index of pure silica glass, forming a core in the groove, and forming a second cladding layer having a second dopant that lowers the refractive index of the second cladding layer below the refractive index of pure silica glass, over the first cladding layer and the core.

Abstract: An optically amplifying waveguide that can have a gain having a small wave-length dependency in a wavelength range shorter than the C-band, and the like. The optical amplifier module 1 optically amplifies a signal lightwave that has a wavelength lying in a wavelength range of 1,490 to 1,530 nm and that has entered an input connector 11 to output the optically amplified signal lightwave from an output connector 12. An optical isolator 21, a WDM coupler 31, an Er-doped optical fiber (EDF) 50, a WDM coupler 32, and an optical isolator 22 are provided in this order on a signal lightwave-transmitting path from the input connector 11 to the output connector 12. A pump source 41 connected to the WDM coupler 31 and a pump source 42 connected to the WDM coupler 32 are also provided. In the EDF 50, at least one of the stimulated-emission cross section and the absorption cross section assumes a maximum value at the shorter-wavelength side of a peak at a wavelength range of 1.53 ?m.

Abstract: To provide an optical device whereby the optical characteristics of a lightwave circuit element can be varied with low power consumption. There is provided an optical device comprising a lightwave circuit element having one or plurality of optical waveguides, and also having a refractive index adjusting portion composed of resin located in the one or plurality of optical waveguides and/or in a portion of the area in the one or plurality of optical waveguides. The lightwave circuit element comprises an adjustment-light waveguide for guiding adjustment light that varies the refractive index of the resin, and directing the adjustment light to the adjusting portion.

Abstract: The present invention provides a lightwave circuit device, an optical multiplexer, and an optical demultiplexer with which light can be multiplexed or demultiplexed even when a plurality of lightwaves of varying wavelength are inputted. The lightwave circuit device includes first to third Mach-Zehnder interferometers. The first to third Mach-Zehnder interferometers each have first to third ports, a first optical coupler, first and second optical waveguides, a second optical coupler, and a first heater provided along at least one of the first and the second optical waveguides. The second port of the first Mach-Zehnder interferometer and the first port of the second Mach-Zehnder interferometer are optically coupled, and the third port of the first Mach-Zehnder interferometer and the first port of the third Mach-Zehnder interferometer are optically coupled.

Abstract: The present invention provides a glass optical waveguide device that comprises silica glass and is usable despite a relatively large refractive index difference between its core layer and cladding layer, and a method of manufacturing such device. This optical waveguide device includes a core layer on or over a substrate and a cladding layer that covers the core layer, wherein the core layer is made of silica glass containing an additive for raising the refractive index, and the relative refractive index difference of the core layer with respect to the cladding layer is at least 2.5%.

Abstract: An optical waveguide device and a method of making the same that render excellent transmission loss characteristics and allow a large degree of freedom in circuit design are provided. The method has the steps of forming a fluorine-added silica glass first cladding layer on a substrate, forming a silica glass protective layer on the first cladding layer, annealing, forming a groove that penetrates through the protective layer and reaches the first cladding layer, forming a silica glass core in the groove, and forming a fluorine-added silica glass second cladding layer on the protective layer and the core. The device has a substrate, a first cladding layer formed on the substrate, a protective layer formed on the first cladding layer, a core formed in a groove that penetrates through the protective layer and reaches the first cladding layer, and a second cladding layer formed on the protective layer and the core.

Abstract: The present invention provides a lightwave circuit device, an optical multiplexer, and an optical demultiplexer with which light can be multiplexed or demultiplexed even when a plurality of lightwaves of varying wavelength are inputted. The lightwave circuit device includes first to third Mach-Zehnder interferometers. The first to third Mach-Zehnder interferometers each have first to third ports, a first optical coupler, first and second optical waveguides, a second optical coupler, and a first heater provided along at least one of the first and the second optical waveguides. The second port of the first Mach-Zehnder interferometer and the first port of the second Mach-Zehnder interferometer are optically coupled, and the third port of the first Mach-Zehnder interferometer and the first port of the third Mach-Zehnder interferometer are optically coupled.

Abstract: To provide an optical device whereby the optical characteristics of a lightwave circuit element can be varied with low power consumption. There is provided an optical device comprising a lightwave circuit element having one or plurality of optical waveguides, and also having a refractive index adjusting portion composed of resin located in the one or plurality of optical waveguides and/or in a portion of the area in the one or plurality of optical waveguides. The lightwave circuit element comprises an adjustment-light waveguide for guiding adjustment light that varies the refractive index of the resin, and directing the adjustment light to the adjusting portion.

Abstract: A method of manufacturing an optical waveguide device that is capable of reducing the imbalance in the refractive index profile of a core, and an optical waveguide device that has the reduced imbalance in the refractive index profile are provided. The method of manufacturing an optical waveguide device has the steps of forming a groove in a first cladding layer having a first dopant that lowers the refractive index of the first cladding layer below the refractive index of pure silica glass, forming a core in the groove, and forming a second cladding layer having a second dopant that lowers the refractive index of the second cladding layer below the refractive index of pure silica glass, over the first cladding layer and the core.

Abstract: In a method of manufacturing an optical waveguide device, the surface of a core can be planarized in a concaving process. In this manufacturing method, a plasma CVD apparatus having a coil for producing plasma and a table for mounting products is used. In the method, a first cladding having a concavity is mounted on the table, a core film is formed on the first cladding while high-frequency electric power P1 is supplied to the coil and high-frequency electric power P2 is supplied to the table, a resist film is formed on the core film, a core is formed in the concavity by etching the resist film and the core film, and a second cladding is formed on the first cladding and the core.