| 摘要 |
<p>A tunable laser includes an optical waveguide (1), made up of alternating gain waveguide portions (1A) and wavelength controlling waveguide portions (1B), and a diffraction grating (2). The diffraction grating includes a gain diffraction grating (2A) and a wavelength controlling diffraction grating (2B). A wavelength controlling region (11B) is constituted by the wavelength controlling waveguide portion and the wavelength controlling diffraction grating. A gain region (11A) is constituted by the gain waveguide portion and the gain diffraction grating. The Bragg wavelength of the wavelength controlling region is longer than that of the gain region in a state in which current injection or voltage application is not performed for the wavelength controlling waveguide portion.</p> |
