| 摘要 |
PURPOSE:To miniaturize an element by forming gratings having periodical structures, whose phases are shifted from each other by 180 deg. in the light propagation direction, on first and second cores respectively. CONSTITUTION:A grating 6 as a periodical ruggedness on a core 3 is formed besides two asymmetrical cores 2 and 3 and a grating 4. Periodical structures of the grating 4 formed on the first core 2 and the grating 6 formed on the second core 3 in the coupling part have phases shifted from each other by 180 deg. in the light propagation direction. Thus, a coupling coefficient is increased, and the length of the coupling part 5 is shortened to a half conventional length, and the element is miniaturized. |
