Abstract: A control method of an optical element, including light sources to emit lights having different wavelengths from each other, and ring modulators connected in cascade along a light waveguide, is disclosed. Each ring modulator includes a ring resonator, and a wavelength adjustment electrode to adjust a resonance wavelength in the ring resonator, wherein the lights from the light sources are multiplexed to enter the light waveguide. The method includes having a light source emit the light; adjusting power to the wavelength adjustment electrode in each ring modulator, to obtain a value of the power causing the resonance wavelength of the ring resonator, equivalent to the wavelength of the light emitted from the light source; obtaining a relationship between the light sources and the values of the power corresponding to the ring modulators; and selecting the ring modulators corresponding to the light sources based on the relationship.

Abstract: An optical switch includes a substrate, a ring resonator formed on the substrate, a first waveguide formed on the substrate in optical coupling with the ring resonator, the first waveguide being configured to guide a WDM signal, an optical detector configured to detect an optical signal component in said ring resonator, a temperature regulator driven in response to an output signal of the optical detector, the temperature regulator being configured to change a temperature of the ring resonator, the ring resonator having a resonant wavelength corresponding to a wavelength of an optical signal component that constitutes the WDM signal, the ring resonator, the optical detector and the temperature regulator constituting together a feedback control system that locks the resonant wavelength of the ring resonator to the wavelength of the optical signal component in the WDM signal.

Abstract: A control method of an optical element, including light sources to emit lights having different wavelengths from each other, and ring modulators connected in cascade along a light waveguide, is disclosed. Each ring modulator includes a ring resonator, and a wavelength adjustment electrode to adjust a resonance wavelength in the ring resonator, wherein the lights from the light sources are multiplexed to enter the light waveguide. The method includes having a light source emit the light; adjusting power to the wavelength adjustment electrode in each ring modulator, to obtain a value of the power causing the resonance wavelength of the ring resonator, equivalent to the wavelength of the light emitted from the light source; obtaining a relationship between the light sources and the values of the power corresponding to the ring modulators; and selecting the ring modulators corresponding to the light sources based on the relationship.

Abstract: A first ink air chamber is in communication with an air layer in a first ink tank for an ink of a first viscosity in communication with a first inkjet head. A second ink air chamber is in communication with an air layer in a second ink tank for an ink of a second viscosity in communication with a second inkjet head. A first on-off valve opens or closes communication between the first and second ink air chambers. A second on-off valve opens or closes communication between the second ink air chamber and the atmosphere. A pressure adjuster is configured to adjust a pressure in the second ink air chamber without intervention of the first ink air chamber. A controller is configured to drive the pressure adjuster to increase the pressure in the second ink air chamber with the first and second on-off valves being closed.

Abstract: A determiner determines whether a total ink amount in an ink circulation passage calculated by an ink amount calculator is less than an ink circulation necessary amount being an amount necessary for circulation of ink in the ink circulation passage, when a liquid level detector detects that a liquid level of the ink in an ink tank is lower than a liquid level corresponding to an ink circulation standard amount being a standard for ink circulation. A controller performs ink supply amount control to supply the ink from an ink bottle to the ink tank in such an amount that the total ink amount is kept below the ink circulation standard amount, when the determiner determines that the total ink amount is less than the ink circulation necessary amount.

Abstract: An optical semiconductor device includes a laser oscillator on a semiconductor substrate; and an optical modulator on the semiconductor substrate. The laser oscillator includes a pair of reflecting mirrors at least one of which is a loop mirror, and the loop mirror includes a loop waveguide and a plurality of first ring resonators serially inserted in the loop waveguide. The optical modulator includes a plurality of second ring resonators connected in cascade along a modulator waveguide. A transmission band width of the first ring resonator is set greater than a transmission band width of the second ring resonator.

Abstract: A first ink air chamber is in communication with an air layer in a first ink tank for an ink of a first viscosity in communication with a first inkjet head. A second ink air chamber is in communication with an air layer in a second ink tank for an ink of a second viscosity in communication with a second inkjet head. A first on-off valve opens or closes communication between the first and second ink air chambers. A second on-off valve opens or closes communication between the second ink air chamber and the atmosphere. A pressure adjuster is configured to adjust a pressure in the second ink air chamber without intervention of the first ink air chamber. A controller is configured to drive the pressure adjuster to increase the pressure in the second ink air chamber with the first and second on-off valves being closed.

Abstract: A determiner determines whether a total ink amount in an ink circulation passage calculated by an ink amount calculator is less than an ink circulation necessary amount being an amount necessary for circulation of ink in the ink circulation passage, when a liquid level detector detects that a liquid level of the ink in an ink tank is lower than a liquid level corresponding to an ink circulation standard amount being a standard for ink circulation. A controller performs ink supply amount control to supply the ink from an ink bottle to the ink tank in such an amount that the total ink amount is kept below the ink circulation standard amount, when the determiner determines that the total ink amount is less than the ink circulation necessary amount.

Abstract: An optical semiconductor device includes a laser oscillator on a semiconductor substrate; and an optical modulator on the semiconductor substrate. The laser oscillator includes a pair of reflecting mirrors at least one of which is a loop mirror, and the loop mirror includes a loop waveguide and a plurality of first ring resonators serially inserted in the loop waveguide. The optical modulator includes a plurality of second ring resonators connected in cascade along a modulator waveguide. A transmission band width of the first ring resonator is set greater than a transmission band width of the second ring resonator.

Abstract: An optical semiconductor device includes a ring waveguide, and a serpentine waveguide configured to be optically connected to the ring waveguide and surround at least a part of the ring waveguide in a serpentine form. In the optical semiconductor device, the serpentine waveguide heats the ring waveguide by absorbing input light propagated from the ring waveguide to the serpentine waveguide.

Abstract: The present invention is a laser system including a DFB laser 10 emitting a laser light 50, a semiconductor optical amplifier 20 that modulates an intensity of the laser light, and a harmonic generation element 30 that converts the laser light modulated to a visible light 54 that is a harmonic of the laser light. According to the present invention, it is possible to employ the highly efficient harmonic generation element capable of modulating the intensity of the laser light and to reduce power consumption.

Abstract: An optical semiconductor element includes a ring modulator, and a light absorbing material provided at a position apart from a path for a modulated light which is guided by the ring modulator, the light absorbing material absorbing a light leaked out of a ring waveguide of the ring modulator, and increasing a temperature of the ring waveguide.

Abstract: An optical semiconductor device includes a ring laser including a ring resonator in which an optical gain element having an optical gain by current injection is provided, a waveguide optically coupled to the ring laser, and a reflector provided at an end portion of the waveguide and configured to reverse the advancing direction of light outputted from the ring laser and propagating in the waveguide.

Abstract: An optical switch includes a substrate, a ring resonator formed on the substrate, a first waveguide formed on the substrate in optical coupling with the ring resonator, the first waveguide being configured to guide a WDM signal, an optical detector configured to detect an optical signal component in said ring resonator, a temperature regulator driven in response to an output signal of the optical detector, the temperature regulator being configured to change a temperature of the ring resonator, the ring resonator having a resonant wavelength corresponding to a wavelength of an optical signal component that constitutes the WDM signal, the ring resonator, the optical detector and the temperature regulator constituting together a feedback control system that locks the resonant wavelength of the ring resonator to the wavelength of the optical signal component in the WDM signal.

Abstract: An apparatus includes an optical semiconductor element comprising: a waveguide into which input light is input; a plurality of ring modulators that have different optical perimeter lengths and are optically coupled to the waveguide; and a control unit configured to selectively apply a modulation signal to at least one of the plurality of ring modulators having a resonant wavelength that is the same as a wavelength of the input light.

Abstract: An optical semiconductor device includes a waveguide that an input light to be inputted, a ring modulator optically coupled with the waveguide, a first ring resonator optically coupled with the waveguide and having an optical path length smaller than an optical path length of the ring modulator, a second ring resonator optically coupled with the first waveguide and having an optical path length larger than the optical path length of the ring modulator, a heater arranged adjacent to the ring modulator, the first ring resonator and the second ring resonator, a first photodetector monitoring a light power in the first ring resonator, a second photodetector monitoring a light power in the second ring resonator, and a controller controlling the heater so that a resonance wavelength of the ring modulator agrees with a wavelength of the input light, based on signals detected by the first and second photodetectors.

Abstract: An inkjet printing apparatus includes: an inkjet head configured to discharge ink; a first tank configured to store ink to be supplied to the inkjet head; a second tank configured to store ink not consumed by the inkjet head; an ink circulation path for circulation of ink among the first tank, the inkjet head, and the second tank; a pressurizer configured to provide the first and second tanks with a pressure for the circulation of ink through the ink circulation path; a first pressure adjuster configured to adjust a pressure inside the first tank during the circulation of ink; and a second pressure adjuster configured to adjust a pressure inside the second tank during the circulation of ink.

Abstract: A detachable structure for an ink cartridge in a printer includes a storing unit, an acquisition unit, a determining unit, and an ink supply control unit. The storing unit is provided on the ink cartridge and stores information on the ink cartridge. The acquisition unit is provided on the printer and acquires the information stored in the storing unit when the ink cartridge is attached onto the printer. The determining unit certifies validity of the information acquired by the acquisition unit. The ink supply control unit allows ink supply from the ink cartridge when the validity of the information is certified by the determining unit. According to the structure, versatility of ink cartridges can be ensured and productivity cost for ink cartridges can be restricted. In addition, prevented can be undesirable ink mixture due to an erroneous installation of the ink cartridge by a user.

Abstract: A detachable structure for an ink cartridge includes a supply port, a joint section, an insertion rod and an anti-outflow member. The port is provided in the cartridge. The stopper is provided in the port and urged outward to close the port. The joint section is provided in a printer and coupled with the port. The joint section has an ink flow path that communicates with the port while the port is coupled. The insertion rod is provided in the joint section for pushing the stopper inward to communicate the ink flow path with the port while the port is coupled. The anti-outflow member is slidably provided in the joint section. The anti-outflow member is urged outward and slides along the insertion rod when the port is being inserted into the joint section. According to the structure, ink leakage on attaching or detaching of the cartridge can be prevented.

Abstract: The present invention provides a semiconductor laser including a first conductive type of a lower clad layer 12, an active layer 14 provided on the lower clad layer 12, the active layer 14 including a plurality of quantum dots, and a second conductive type of an upper clad layer 18, the upper clad layer 18 being provided on the active layer 14 so as to have an isolated ridge portion 30 such that W1?Wtop+0.4 ?m where Wtop is the width of a top of the ridge portion 30 and W1 is the width of the ridge portion 30 at a height of 50 nm from a bottom of the ridge portion 30. The present invention also provides a method for manufacturing such a semiconductor laser.