摘要 |
<p>A semiconductor laser has a first diffractive grating area. The first diffractive grating area has a plurality of segments. Each segment has a first area including a diffractive grating (2) and a second area that is space area combined to the first area. Optical lengths of at least two of the second areas are different from each other. A refractive-index of each of the segments are changeable.
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