| abstract |
The present invention provides a compact wavelength tunable light source that blocks unnecessary light generated during wavelength switching and outputs only laser light of a desired wavelength. According to the present invention, laser light emitted in a predetermined region on a substrate is branched into at least two optical waveguides, and the at least one optical waveguide has an optical gate function that operates based on an external signal. In addition, other optical waveguides have a light passing or amplification function, so that the light passing through the former is used as signal light, and the light passing through the latter is guided to the wavelength monitor, so that the wavelength can be changed during wavelength switching. Unnecessary signal light can be blocked while operating the monitor. [Selection] Figure 1 |