US Patent 11984699 Optical semiconductor device and control method of the same

Provided is an optical semiconductor device including: a wavelength tunable laser element; a beam splitter that splits an outgoing beam of the wavelength tunable laser element into a first light beam and a second light beam parallel to each other, and outputs the first light beam and the second light beam; and an etalon that transmits the first light beam and the second light beam, wherein an optical path length to the first light beam of the etalon is different from an optical path length to the second light beam of the etalon.