| 摘要 |
PURPOSE:To reduce a loss by a chromatic aberration of a lens by constituting so that the shorter the wavelength is, the larger a lens interval becomes, in an optical demultiplexer and multiplexer which contains an optical filter between a pair of optical lenses and branches or combines three or more beams of light. CONSTITUTION:Beams of light of wavelengths lambda1-lambda3, which are made incident to an input optical fiber 1 become almost parallel beams by a rod lens 5, transmit through prisms 9, 16 and are made incident to a dielectric multi-layer film 13. The light of the wavelength lambda1 transmits through the multi-layer film 13 and is made incident to an optical fiber 6. The light of the wavelengths lambda2, lambda3 are reflected, made incident to a multi-layer film 14, and the light of the wavelength lambda2 is made incident to an optical fiber 3. The light of the wavelength lambda3 is reflected, passes through a multi-layer film 15 and is made incident to an optical fiber 4. The shorter the wavelength of the light is, the larger a lens interval of each one pair of lenses 5-8 is made, by which a chromatic aberration is reduced and a conversion to a low loss of light is realized. |
