Patent ID: 8861557

Claim:
A wavelength-tunable light source comprising: a plurality of light sources having differing variable wavelength regions, where light sources having adjacent wavelength regions are distributed to different systems; a first coupling device that couples light output by the light sources included in the same system; an optical switching device that transmits or blocks light included in the same system; a second coupling device that couples light of the different systems and outputs the coupled light; and a control unit that controls driving of each of the light sources and the optical switching device, wherein the light sources are each set such that an end portion of the variable wavelength region of the light source overlaps an end portion of the variable wavelength region of another light source, and the control unit selects and drives a first light source among the light sources of a first system that is among the different systems, varies a wavelength of the first light source, the control unit further selects a second light source that is of a second system among the different systems and that has a wavelength region overlapping the variable wavelength region of the first light source, the control unit further drives the second light source concurrently with the first light source and subsequently switches to the output light of the second light source, causing wavelength variation and executing continuous wavelength variation over a wide range.