| 摘要 |
PURPOSE:To achieve improvement of the coupling efficiency with an optical fiber without using a complex optical system by making the refractive index waveguide take a predetermined shape. CONSTITUTION:A waveguide, formed by an active layer 1 and having a rectangular entrance end face, of a semiconductor laser 5 provided with a mode field conversion part 7 has a circular exit end face 3 on the conversion part 7 side. And, in the conversion part 7, a refractive index waveguide 4 is formed in which the rectangular part and the circular part are smoothly coupled, whereby the coupling efficiency with an optical fiber is enhanced without using a complex optical system.
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