Patent ID: 11909173
Assignee: FURUKAWA ELECTRIC CO., LTD.
Field: Optics (Instruments)
Classification: CPC H | IPC H

Claim 9:
10. A waveguide based wavelength-tunable laser formed on a semiconductor substrate, the wavelength-tunable laser comprising:
a first reflector from which laser light is output;
a second reflector configuring a laser resonator together with the first reflector;
a gain portion that is provided between the first reflector and the second reflector;
at least two wavelength filters that can adjust wavelength characteristics and adjust a wavelength of the laser light;
a phase adjuster that adjusts an optical path length in the laser resonator, wherein
a folded portion configured by a waveguide that folds back an optical path by an angle of substantially 180 degrees is provided between the first reflector and the second reflector;
a semiconductor optical amplifier that is provided on a laser light output side of the first reflector on the semiconductor substrate; and
an optical branching portion that is provided between the first reflector and the semiconductor optical amplifier and branches a part of the laser light that is output from the first reflector to the semiconductor optical amplifier, a waveguide guiding the part of the laser light branched reaching an end facet other than an end facet from which the laser light is output.