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

Claim 16:
17. A waveguide based wavelength-tunable laser formed on a semiconductor substrate, 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;
a semiconductor optical amplifier that is provided on a laser light output side of the first reflector, 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 semiconductor optical amplifier, 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.