| 摘要 |
PURPOSE:To form a small-sized and very economical optical demultiplexer, by utilizing a slab type plane light guide which has an amorphous semiconductor film with a diffraction grating on its one end surface. CONSTITUTION:The slab type plane light guide 30 is formed by using a glass substrate 21 with a low refractive index as a clad and a glass substrate 22 with a high refractive index as a core, and its end surface 23 is polished optically. Then, the amorphous semiconductor of an As-S system, etc., is vapor-deposited on the end surface 23 to form a film 24, on which interference fringes of laser light are written to form the diffraction grating 25. For example, when a wavelength multiplex light wave 34 of wavelengths lambda1 and lambda2 is incident to the core 22 of the light guide 30 through a fiber 41, this light spreads in a beam shape while propagating in the core 22 and is reflected between positions 26 and 27 of the diffraction grating 25, and its reflected light beams 55 and 56 are focused and made incident to output fibers 51 and 61 separately by the wavelengths, thus performing demultiplexing into a light wave 35 (wavelength lambda1) and a light wave 36 (wavelength lambda2). |
