A light source unit (1000) of the present disclosure includes a light source part (100), a first electrical signal generating device (40-1) configured to control current that drives an optical semiconductor device (30), an optical modulator (200) having a Mach-Zehnder type optical waveguide (10) and an electrode configured to apply an electric field to the optical waveguide (10), and a second electrical signal generating device (40-2) configured to control a voltage that operates the optical modulator (200), the first electrical signal generating device (40-1) and the second electrical signal generating device (40-2) are synchronizably connected to each other, and intensity of light emitted from the optical modulator (200) is changed by the current controlled by the first electrical signal generating device (40-1) and the voltage controlled by the second electrical signal generating device (40-2).

A light source unit (1000) of the present disclosure includes a light source part (100), a first electrical signal generating device (40-1) configured to control current that drives an optical semiconductor device (30), an optical modulator (200) having a Mach-Zehnder type optical waveguide (10) and an electrode configured to apply an electric field to the optical waveguide (10), and a second electrical signal generating device (40-2) configured to control a voltage that operates the optical modulator (200), the first electrical signal generating device (40-1) and the second electrical signal generating device (40-2) are synchronizably connected to each other, and intensity of light emitted from the optical modulator (200) is changed by the current controlled by the first electrical signal generating device (40-1) and the voltage controlled by the second electrical signal generating device (40-2).

Provided is an optical phase shifter. The optical phase shifter includes: a silicon substrate; a cladding layer disposed on the silicon substrate; an intermediate film disposed on the cladding layer; a KTN (KTaNbO.sub.3) waveguide disposed on the intermediate film; a protective layer disposed on the intermediate film to cover the KTN waveguide; and first and second electrodes disposed on the intermediate film while being spaced apart from each other with the KTN waveguide interposed between the first and second electrodes, wherein a silicon waveguide is disposed inside the cladding layer while being spaced apart from the KTN waveguide with the intermediate film interposed between the silicon waveguide and the KTN waveguide.

Provided is an optical phase shifter. The optical phase shifter includes: a silicon substrate; a cladding layer disposed on the silicon substrate; an intermediate film disposed on the cladding layer; a KTN (KTaNbO.sub.3) waveguide disposed on the intermediate film; a protective layer disposed on the intermediate film to cover the KTN waveguide; and first and second electrodes disposed on the intermediate film while being spaced apart from each other with the KTN waveguide interposed between the first and second electrodes, wherein a silicon waveguide is disposed inside the cladding layer while being spaced apart from the KTN waveguide with the intermediate film interposed between the silicon waveguide and the KTN waveguide.

An optical phase modulator comprises a cascaded array of optical resonators, wherein each of the optical resonators has an input port and an output port. A plurality of waveguides are coupled between the optical resonators and are configured to provide cascaded optical communication between the optical resonators. Each of the waveguides is respectively coupled between the output port of one optical resonator and the input port of an adjacent optical resonator. A transmission electrode is positioned adjacent to the optical resonators, with the transmission electrode configured to apply a drive voltage across the optical resonators. The optical phase modulator is operative to co-propagate an input optical wave with the drive voltage, such that a resonator-to-resonator optical delay is matched with a resonator-to-resonator electrical delay.

An optical phase modulator comprises a cascaded array of optical resonators, wherein each of the optical resonators has an input port and an output port. A plurality of waveguides are coupled between the optical resonators and are configured to provide cascaded optical communication between the optical resonators. Each of the waveguides is respectively coupled between the output port of one optical resonator and the input port of an adjacent optical resonator. A transmission electrode is positioned adjacent to the optical resonators, with the transmission electrode configured to apply a drive voltage across the optical resonators. The optical phase modulator is operative to co-propagate an input optical wave with the drive voltage, such that a resonator-to-resonator optical delay is matched with a resonator-to-resonator electrical delay.

Provided is an optical waveguide device in which both signal electrode collapse and signal electrode peeling/damage can be prevented. An optical waveguide device in which an optical waveguide is formed on a substrate and a control electrode for controlling a light wave propagating through the optical waveguide is disposed on the substrate, is characterized in that, the control electrode includes a signal electrode, and the signal electrode has a narrow portion, where a width of the signal electrode on a substrate side is narrow, and a wide portion, where a width of the signal electrode on an upper portion side of the signal electrode is wide, a prevention film that is disposed in contact with the narrow portion of the signal electrode and that prevents the signal electrode from collapsing, is provided on the substrate, and at a position of the signal electrode where the narrow portion and the wide portion are connected, a surface of the prevention film is formed as a curved surface protruding toward the signal electrode, and a side surface of the signal electrode is formed along the curved surface.

Provided is an optical waveguide device in which both signal electrode collapse and signal electrode peeling/damage can be prevented. An optical waveguide device in which an optical waveguide is formed on a substrate and a control electrode for controlling a light wave propagating through the optical waveguide is disposed on the substrate, is characterized in that, the control electrode includes a signal electrode, and the signal electrode has a narrow portion, where a width of the signal electrode on a substrate side is narrow, and a wide portion, where a width of the signal electrode on an upper portion side of the signal electrode is wide, a prevention film that is disposed in contact with the narrow portion of the signal electrode and that prevents the signal electrode from collapsing, is provided on the substrate, and at a position of the signal electrode where the narrow portion and the wide portion are connected, a surface of the prevention film is formed as a curved surface protruding toward the signal electrode, and a side surface of the signal electrode is formed along the curved surface.

A phase shifter includes a first cladding layer, a first core formed on the first cladding layer, and a second core formed on the first core. The first cladding layer and the first core are formed from a first material having an electrooptical effect. The second core is formed from a second material having a refractive index higher than that of the first material. The phase shifter includes a first metal layer and a second metal layer formed on side surfaces of both of the first core and the second core.

A phase shifter includes a first cladding layer, a first core formed on the first cladding layer, and a second core formed on the first core. The first cladding layer and the first core are formed from a first material having an electrooptical effect. The second core is formed from a second material having a refractive index higher than that of the first material. The phase shifter includes a first metal layer and a second metal layer formed on side surfaces of both of the first core and the second core.