| 摘要 |
PURPOSE:To decrease the increase of loss owing to the chromatic aberration in a demultiplexer consisting of a combination of short and long wavelengths by forming said demultiplexer in such a way that the end face angles of respective optical fibers are formed near the critical angle of the optical fibers or above. CONSTITUTION:Light emitting diodes of which the wavelengths lambda1, lambda2, lambda3 are made respectively 0.81mum, 0.89mum, 1.3mum are used for a bidirectional demultiplexer for three wavelengths. Signals having respectively the wavelengths lambda1, lambda2, lambda3 and inputted or outputted to and from the optical fibers 11-14. The polished optical fibers 11-14 are so positioned that the output end of the light having the longest wavelength is further from the end of a convergent rod lens 16 and the end having the shorter wavelength is nearer th lens end. A glass block 17 for filling the space between a lens 16 and the optical fiber bundle formed by forming integrally the fibers 11-14 sandwiched by quartz plates 15, 15' has partly a multi-layered dielectric film filter 18. A multi-layered dielectric film filter 19 reflects light of the wavelength lambda1 and allows transmission of the light of lambda2, lambda3. Filters 20, 21 reflect the light of the wavelength lambda2 and allows transmission of the light of lambda3. The filters 10-21 are attached by an optical adhesive agent 22 so as to be coupled to an optical fiber 14 of a common terminal. |
