| 摘要 |
PROBLEM TO BE SOLVED: To perform continuous tuning over a wide wavelength range. SOLUTION: This element 100 is provided with a first passive waveguide 110a where a first Bragg diffraction grating 150a with a uniform grating cycle is formed, a second passive waveguide 110c where a second Bragg diffraction grating 150c with a non-uniform grating cycle is formed, and an active waveguide 110b for connecting the first passive waveguide 110a and the second passive waveguide 110c. In this case, the grating cycle of the second Bragg diffraction grating 150c is made longer as separating from the active waveguide 110b. Thus, the reflection position of light P1 in the second passive waveguide 110c indicates wavelength dependency, and wavelength tuning is made possible without causing mode skipping. As a result, the wavelength range capable of continuous tuning is enlarged.
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