| 摘要 |
PROBLEM TO BE SOLVED: To make a conventional mechanical movable part unnecessary for selecting a recording layer where reference light propagates in an optical waveguide type hologram recording medium. SOLUTION: Each recording layer (21 to 24) is provided with a grating 5 to couple reference light B1 to an optical waveguide (core layer 2); the core layer 2 is made of an electrorefractive material which changes refractive indices depending on an external electric field; and transparent electrode layers (25 to 29) are disposed to interpose each recording layer. By controlling the refractive indices of the layers to be identical when no driving voltage is applied, the grating 5 is not optically activated in each layer and the reference light B1 does not propagate in any recording layer. The refractive index of the core layer 2 only in a recording layer with a driving voltage applied increases to activate the grating 5, and by selecting a recording layer where a driving voltage is applied, a recording layer where the reference light B1 propagates can be selected. Thus, a conventional mechanical movable part can be omitted. COPYRIGHT: (C)2006,JPO&NCIPI |
