Abstract: A method for tuning a semiconductor laser including a plurality of wavelength selection portions, each of which has a periodic wavelength characteristic, including: controlling a value of a refractive index controlling means of the wavelength selection portions to achieve a desired output wavelength of the laser; and shifting the value when the value is equal to or excess of a predetermined value to a basal value side until achieving the desired output wavelength, the basal value being a value without applying refractive index variation by the refractive index controlling means, the predetermined value being a value for shifting one period of the periodic wavelength characteristic.

Abstract: A method for tuning a semiconductor laser including a plurality of wavelength selection portions, each of which has a periodic wavelength characteristic, including: controlling a value of a refractive index controlling means of the wavelength selection portions to achieve a desired output wavelength of the laser; and shifting the value when the value is equal to or excess of a predetermined value to a basal value side until achieving the desired output wavelength, the basal value being a value without applying refractive index variation by the refractive index controlling means, the predetermined value being a value for shifting one period of the periodic wavelength characteristic.

Abstract: A testing method of a wavelength-tunable laser having a resonator including wavelength selection portions having wavelength property different from each other includes a first step of controlling the wavelength-tunable laser so as to oscillate at a given wavelength according to an initial setting value, a second step of tuning the wavelength property of the wavelength selection portions and detecting discontinuity point of gain-condition-changing of the wavelength-tunable laser, and a third step of obtaining a stable operating point of the wavelength selection portion according to a limiting point of an oscillation condition at the given wavelength, the limiting point being a point when the discontinuity point is detected.

Abstract: A laser device includes a resonator having a gain region, a first wavelength selection portion having a periodical peak in wavelength characteristics and a second wavelength selection portion having a periodical peak in wavelength characteristics in a wavelength range smaller than a variable range of an oscillation wavelength at a period different from the first wavelength selection portion, the oscillation wavelength selected with a single direction changing of a refractive index of the second wavelength selection portion changing in a single direction; a storing portion storing a setting value of a refractive index of the second wavelength selection portion for selecting an oscillation wavelength according to an oscillation wavelength to be attained within an extent from a maximum value to a minimum value of the refractive index over the plurality of the ranges; and a controller giving the setting value to the resonator.

Abstract: An optical device includes an optical element, a detector and a controller. The optical element has an optical waveguide. Refractive index of the optical waveguide is controlled by a heater. A temperature of the optical element is controlled by a temperature control device. The detector detects a current flowing in the heater and/or a voltage applied to the heater. The controller controls an electrical power provided to the heater so as to be kept constant according to the detection result of the detector.

Abstract: A method of controlling a semiconductor laser that has a plurality of wavelength selection portions having a different wavelength property from each other and is mounted on a temperature control device, including: a first step of correcting a temperature of the temperature control device according to a detected output wavelength of the semiconductor laser; and a second step of controlling at least one of the wavelength selection portions so that changing amount differentials between each wavelength property of the plurality of the wavelength selection portions is reduced, the changing amount differential being caused by correcting the temperature of the temperature control device.

Abstract: A testing method of a wavelength-tunable laser having a resonator including wavelength selection portions having wavelength property different from each other includes a first step of controlling the wavelength-tunable laser so as to oscillate at a given wavelength according to an initial setting value, a second step of tuning the wavelength property of the wavelength selection portions and detecting discontinuity point of gain-condition-changing of the wavelength-tunable laser, and a third step of obtaining a stable operating point of the wavelength selection portion according to a limiting point of an oscillation condition at the given wavelength, the limiting point being a point when the discontinuity point is detected.

Abstract: An optical device includes an optical element, a detector and a controller. The optical element has an optical waveguide. Refractive index of the optical waveguide is controlled by a heater. A temperature of the optical element is controlled by a temperature control device. The detector detects a current flowing in the heater and/or a voltage applied to the heater. The controller controls an electrical power provided to the heater so as to be kept constant according to the detection result of the detector.

Abstract: A method of controlling a semiconductor laser that has a plurality of wavelength selection portions having a different wavelength property from each other and is mounted on a temperature control device, including: a first step of correcting a temperature of the temperature control device according to a detected output wavelength of the semiconductor laser; and a second step of controlling at least one of the wavelength selection portions so that changing amount differentials between each wavelength property of the plurality of the wavelength selection portions is reduced, the changing amount differential being caused by correcting the temperature of the temperature control device.

Abstract: A method of controlling a semiconductor laser having a wavelength selection portion, a refractive index of the wavelength selection portion being controllable with a heater including: a starting sequence including a first step for adjusting a heat value of the heater until the heat value of the heater reaches a given value; and a wavelength control sequence including a second step for correcting a wavelength of the semiconductor laser according to a detection result of an oscillation wavelength of the semiconductor laser after the starting sequence.

Abstract: An optical semiconductor device includes a package body, a laser diode accommodated in the package body, a temperature regulation block connected thermally to the laser diode, an optical filter connected thermally to the temperature regulation block, a photodetector receiving the laser beam from the laser diode via the optical filter, a feeder feeding a driving power to the laser diode, and a thermal conducting body provided separately to the feeder, wherein the thermal conducting body transmits the temperature of the package body to the laser diode.

Abstract: An optical semiconductor device includes a package body, a laser diode accommodated in the package body, a temperature regulation block connected thermally to the laser diode, an optical filter connected thermally to the temperature regulation block, a photodetector receiving the laser beam from the laser diode via the optical filter, a feeder feeding a driving power to the laser diode, and a thermal conducting body provided separately to the feeder, wherein the thermal conducting body transmits the temperature of the package body to the laser diode.