Patent ID: 9614349
Date: 2017-04-04
CPC Classifications: H01S

Claim:
1. A method for switching an output wavelength of a tunable wavelength laser, the tunable wavelength laser being provided with a first temperature control device and a wavelength detecting section including an etalon being provided with a second temperature control device, the first temperature control device controlling a temperature of the tunable wavelength laser, the second temperature control device controlling a temperature of the etalon, the wavelength detecting section identifying the output of the tunable wavelength laser by a ratio of intensity of light input to the etalon against intensity of light output from the etalon, and the output wavelength of the tunable wavelength laser being controlled to a target wavelength based on a detection result of the wavelength detecting section, the method comprising: a first step of driving the tunable wavelength laser at a first wavelength; a second step of, after the first step, suppressing intensity of light output from the tunable wavelength laser in response to a command indicating preset intensity of light output from the tunable wavelength laser at a second wavelength different from the first wavelength; a third step of, after the second step, starting control of the first temperature control device such that the temperature of the tunable wavelength laser becomes close to a second target temperature value of the tunable wavelength laser corresponding to the second wavelength, and starting control of the second temperature control device such that the temperature of the etalon becomes close to the second target temperature of the etalon corresponding to the second wavelength, the second target temperature value of the etalon being different from a first target temperature of the etalon corresponding to the first wavelength; a fourth step of, before a second temperature value of the etalon reaches the second target temperature of the etalon, detecting whether the temperature of the etalon enters within a temperature range of the etalon corresponding to an allowable wavelength range around the second wavelength of the tunable wavelength laser, and, before the second temperature value of the etalon reaches the second target temperature of the etalon, cancelling the suppression of the intensity of the light output from the tunable wavelength laser in response to the detection, and a fifth step of detecting whether the temperature of the tunable wavelength laser reaches the second target temperature value of the tunable wavelength laser, and identifying the output of the tunable wavelength laser by a ratio of intensity of light input to the etalon against intensity of light output from the etalon, and the output wavelength of the tunable wavelength laser being controlled to a target wavelength based on a detection result of the wavelength detecting section.