Patent ID: 7978737

Claim:
A laser device comprising: a cavity that has an optical amplifier, a first etalon having a tunable transmission wavelength range, a second etalon provided between the first etalon and the optical amplifier, and mirrors, the second etalon having a plurality of transmission wavelength ranges at a given interval in the transmission wavelength range of the first etalon, the second etalon being a fixed etalon; and a control portion controlling the first etalon so that the transmission wavelength range of the first etalon is changed to a given range, the control portion controlling the first etalon so that a lasing wavelength of the cavity is a wavelength positioned at longer wavelength side compared to a peak wavelength of the transmission wavelength range of the first etalon in the transmission wavelength range of the first etalon, wherein: an optical intensity of an overlapped peak of the first etalon and the second etalon at the longer wavelength side is reduced because of an optical transmittance of the first etalon at the longer wavelength side being reduced; and the optical intensity of the overlapped peak at shorter wavelength side is reduced because of a gain of the optical amplifier being reduced in a range at the shorter wavelength side compared to the lasing wavelength.