Abstract: An optical semiconductor device according to the present disclosure includes a semiconductor substrate, at least one semiconductor laser provided on the semiconductor substrate, an optical multiplexer/demultiplexer circuit provided on the semiconductor substrate, multiplexing or demultiplexing first output light of the semiconductor laser and outputting second output light and third output light, a first waveguide portion provided on the semiconductor substrate, and outputting the second output light from an end face of the semiconductor substrate, and a second waveguide portion including an optical amplifier amplifying the third output light and a reflecting portion and provided on the semiconductor substrate, wherein the reflecting portion includes a diffraction grating that reflects the third output light amplified by the optical amplifier to feed back to the semiconductor laser via the optical amplifier and the optical multiplexer/demultiplexer circuit, and the semiconductor laser and the reflecting porti

Abstract: An optical semiconductor device includes an optical modulator provided on a substrate, an optical waveguide provided on the substrate, one end of the optical waveguide being connected to a light emission side of the optical modulator and another end of the optical waveguide being present at an end portion of the substrate, a phase adjusting unit provided on a path of the optical waveguide and an optical amplification unit provided on the path of the optical waveguide, wherein a minimum value or a maximum value of a transmittance spectrum having a ripple that periodically fluctuates with respect to a frequency because of multiple reflection of light that occurs between the one end and the other end of the optical waveguide is matched with a wavelength of the light input to the optical modulator by phase adjustment of the phase adjusting unit, and an error vector amplitude is minimized.

Abstract: A semiconductor laser device includes a laser section and a modulator section. The laser section has: a first mesa stripe which is formed on a semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the first mesa stripe and are formed on the semiconductor substrate; n-type burying layers formed on respective surfaces of the semi-insulative burying layers; and a p-type cladding layer which covers surfaces of the n-type burying layers and the first mesa stripe. The modulator section has: a second mesa stripe which is formed on the semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the second mesa stripe and are formed on the semiconductor substrate; and a p-type cladding layer which covers surfaces of the semi-insulative burying layers and the second mesa stripe.

Abstract: An electro-absorption modulator of the invention is an electro-absorption modulator which is formed on an InP substrate and modulate incident light according to a voltage applied to that modulator, and which comprises a light absorbing layer for absorbing a portion of the incident light by using an electric field generated by the applied voltage; wherein the light absorbing layer is comprised of a ternary or more complex III-V semiconductor mixed crystal that does not contain Al but contains Bi.

Abstract: Provided is a semiconductor laser device in which a distributed feedback laser part and an electro-absorption modulator part are formed on the same semiconductor substrate, and laser light emitted from the laser part is emitted from an emission end face of the modulator part. The laser part includes a first diffraction grating formed to extend in a direction of an optical axis of the laser light and the modulator part partially including a second diffraction grating formed to extend in the direction of the optical axis of the laser. A non-diffraction grating region in which a diffraction grating is not formed is interposed between the second diffraction grating of the modulator part and an emission end face of the laser part from which the laser light is emitted to the modulator part.

Abstract: An electro-absorption modulator of the invention is an electro-absorption modulator which is formed on an InP substrate and modulate incident light according to a voltage applied to that modulator, and which comprises a light absorbing layer for absorbing a portion of the incident light by using an electric field generated by the applied voltage; wherein the light absorbing layer is comprised of a ternary or more complex III-V semiconductor mixed crystal that does not contain Al but contains Bi.

Abstract: A semiconductor laser device includes a laser section and a modulator section. The laser section has: a first mesa stripe which is formed on a semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the first mesa stripe and are formed on the semiconductor substrate; n-type burying layers formed on respective surfaces of the semi-insulative burying layers; and a p-type cladding layer which covers surfaces of the n-type burying layers and the first mesa stripe. The modulator section has: a second mesa stripe which is formed on the semiconductor substrate; semi-insulative burying layers which are placed to abut on both side surfaces of the second mesa stripe and are formed on the semiconductor substrate; and a p-type cladding layer which covers surfaces of the semi-insulative burying layers and the second mesa stripe.

Abstract: A method of forming a film on a wafer by decomposing a material gas includes placing the wafer on a top surface of a susceptor, heating the susceptor, measuring the temperature of the top surface of the susceptor. supplying a flow of the material gas to a location above the top surface the susceptor, and thermally decomposing the material gas to deposit a film on the wafer. The quantity of the material gas supplied to the location above the top surface of the susceptor is adjusted and the density of the material gas at the location above the top surface of the susceptor is kept constant by controlling the flow of the material gas to the location above the top surface of the susceptor, including by increasing the flow of the material gas as the temperature of the top surface of the susceptor decreases.

Abstract: A method of manufacturing a semiconductor device, includes forming a laser section on a portion of a substrate, the laser section including an active layer, an upper semiconductor layer on the active layer, and a mask on the upper semiconductor layer; forming a compound semiconductor layer of an indium-containing material in contact with a side of the laser section, the compound semiconductor layer having a projection immediately adjacent the laser section; and wet etching and removing the projection with an etchant containing hydrobromic acid and acetic acid, planarizing the compound semiconductor layer, and producing a (111)A surface in the upper semiconductor layer, under the mask.

Abstract: A method of manufacturing a semiconductor device, includes forming a laser section on a portion of a substrate, the laser section including an active layer, an upper semiconductor layer on the active layer, and a mask on the upper semiconductor layer; forming a compound semiconductor layer of an indium-containing material in contact with a side of the laser section, the compound semiconductor layer having a projection immediately adjacent the laser section; and wet etching and removing the projection with an etchant containing hydrobromic acid and acetic acid, planarizing the compound semiconductor layer, and producing a (111)A surface in the upper semiconductor layer, under the mask.

Abstract: A film forming apparatus includes a susceptor having a first portion that holds a wafer on a top surface of the susceptor and a second portion connected to the first portion, a gas supply section that supplies a material gas to a location above the susceptor, a first heater that heats the first portion, a second heater that heats the second portion, and a temperature control apparatus that controls temperatures of the first heater and the second heater. The temperature control apparatus keeps the temperature above the susceptor constant by increasing the temperature of the second heater while maintaining the temperature of the first heater during formation of a film on the wafer.

Abstract: A method of manufacturing a semiconductor device, includes introducing a substrate into a growth furnace, forming impurity absorption layers on the substrate and on inner walls of the growth furnace, the impurity absorption layers absorbing impurities on a surface of the substrate and impurities in the growth furnace, etching and removing the impurity absorption layers and a portion of the substrate to produce a thinned substrate, forming a buffer layer on the thinned substrate, and forming semiconductor layers on the buffer layer.

Abstract: A semiconductor laser includes a semiconductor laser portion including an active layer portion having a p-type cladding layer, an active layer, and an n-type cladding layer on a p-type InP semiconductor substrate; and current confining structures that fill spaces on both sides of the semiconductor laser portion. Each of the current confining structures includes a first p-type InP layer, a Ru-doped InP layer, and a second p-type InP layer. The Ru-doped InP layer is in contact only with the first and second p-type InP layers. To obtain the structure, timing of introduction of a halogen-containing gas is adjusted.

Abstract: The present invention includes forming an optical guide layer on a substrate, forming a cap layer on the optical guide layer, and forming openings in parts of the optical guide layer and the cap layer to form a diffraction grating from part of the optical guide layer. The substrate is heated to a temperature less than a growth temperature of the cap layer and equal to at least a temperature at which mass transport of the cap layer occurs to cover, with part of the cap layer, the lateral faces of the optical guide layer exposed by the openings. A burying layer burying the diffraction grating is formed on the substrate, after the mass transport.

Abstract: The present invention includes forming an optical guide layer on a substrate, forming a cap layer on the optical guide layer, and forming openings in parts of the optical guide layer and the cap layer to form a diffraction grating from part of the optical guide layer. The substrate is heated to a temperature less than a growth temperature of the cap layer and equal to at least a temperature at which mass transport of the cap layer occurs to cover, with part of the cap layer, the lateral faces of the optical guide layer exposed by the openings. A burying layer burying the diffraction grating is formed on the substrate, after the mass transport.

Abstract: A method for manufacturing a semiconductor laser element includes forming a semiconductor laminated structure, having an active layer, on a substrate; etching the semiconductor laminated structure to form a mesa; exposing the mesa to an oxygen-containing ambient forming an oxide layer on the mesa; removing a first part of the oxide layer from the mesa at a temperature lower than a critical temperature at which bonds between atoms of the oxide layer become stronger, by etching with a gas; removing the remainder of the oxide layer from the mesa at a temperature higher than the critical temperature by etching with a gas; and forming a burying layer coating the mesa.

Abstract: The method for manufacturing a semiconductor laser element according to the present invention has the steps of: forming a semiconductor laminated structure having an active layer composed of a semiconductor material containing Al; etching the semiconductor laminated structure to form a mesa; forming a first burying layer at a first growing temperature so as to coat the side of the mesa; and forming a second burying layer at a second growing temperature higher than the first growing temperature on the first burying layer to bury the circumference of the mesa.

Abstract: A method for manufacturing a semiconductor laser element includes forming a semiconductor laminated structure, having an active layer, on a substrate; etching the semiconductor laminated structure to form a mesa; cleaning the side of the mesa at a temperature lower thank a critical temperature at which an oxide layer forms on the side of the mesa using an etching gas; cleaning the side of the mesa at a temperature higher than the critical temperature using an etching gas; and forming a burying layer coating the side of the mesa after cleaning the side of the mesa.

Abstract: The method for manufacturing a semiconductor laser element according to the present invention has the steps of: forming a semiconductor laminated structure having an active layer composed of a semiconductor material containing Al; etching the semiconductor laminated structure to form a mesa; forming a first burying layer at a first growing temperature so as to coat the side of the mesa; and forming a second burying layer at a second growing temperature higher than the first growing temperature on the first burying layer to bury the circumference of the mesa.