Patent ID: 7701984

Claim:
A laser module comprising: an optical amplifier; a first etalon that has a wavelength peaks at a given wavelength interval in transmission characteristics and that transmits a light from the optical amplifier, the wavelength peaks being tunable; a wavelength selectable mirror that acts as an external mirror of an external cavity laser including the optical amplifier and that has a relatively high reflection intensity at a part of wavelength range in an effective gain range of the optical amplifier, the effective gain range of the optical amplifier including more than one wavelength peak of the first etalon, the wavelength range being smaller than the wavelength interval of the wavelength peaks of the first etalon, only one peak of the first etalon being included in the part of wavelength range of the wavelength selectable mirror; and a second etalon that has a wavelength peaks at a given wavelength interval in transmission characteristics and is arranged between the optical amplifier and the wavelength selectable mirror, the wavelength peaks of the second etalon being fixed.