| 摘要 |
PURPOSE:To prevent an optical beam from leaking from a main waveguide part to a branch waveguide part when an optical switch is not switched, by interposing a low-refractive index layer between the main waveguide part and the branch waveguide part of the optical switch accompanied with no mechanical contact. CONSTITUTION:When a switch 17 is turned off and a DC voltage of a DC power source 18 is not applied to an Nicr 16, namely, at a nonswitching time, the Nicr 16 is not heated, and consequently, the 200mum multi-mode light incident to an optical waveguide 13 from an optical fiber 19 for input is kept in the optical waveguide 13 and is propagated as it is because no temperature distribution is generated near a branch point 15. That is, when no temperature gradient is generated near the branch point 15, a gap area 22 of the 10-20mum low-refractive index layer exists still between the main waveguide 13 and a branch waveguide 14, and the light which tries to go into the gap area 22 is total-reflected because of the relation of n2>n1 (n1 is the refractive index of the low-refractive index layer and n2 is that of the branch waveguide), and all of the light is propagated to the main waveguide 13 as it is, and an output light (g) is led out through an output fiber 20, and thus, leakage of light is prevented. |
