| 摘要 |
1493660 Light guides STANDARD TELEPHONES & CABLES Ltd 16 Dec 1975 51427/75 Heading G2J A waveguide power divider (e.g. for extracting a small amount of power from a main highway, with minimum insertion loss, in a multi-access ring or tree distribution system of a communications system) comprises a tube of transparent dielectric material having a portion of reduced diameter collapsed on to the outer surface of the cladding of an optical fibre extending therethrough, the R.I. of the tube being greater than that of the cladding, In one embodiment, Fig. 2, the power extracted is converted immediately into an electric signal. The divider is made by mounting the fibre 10, 11 within the tube 12 by means of spiders and then rotating the assembly in a lathe while heating the central portion of the tube 12 until it softens and collapses on to the fibre 10, 11. The spiders are removed and an annular photo-detector 20 is fitted against one end of the tube 12. Finally, the two ends of the fibre are provided with connector termination. Light is launched into the fibre from the left and a small amount is coupled into tube 12 over the region in which it contacts the fibre. The assembly may be potted in a resin of R.I. lower than that of cladding 11. In another embodiment, Fig. 3, the extracted power is conveyed as an optical signal to a point remote from the divider. The divider is made by drawing down one end of a glass tube 30, whose bore is lined with a glass layer 31 of higher R.I., to form a solid fibre 32. A hole 35 is then made as shown and a double crank is put into the waveguide in this region so that a straight fibre 39 having a core 36 and cladding 37 can be introduced through the hole 35 centrally within the uncollapsed tube 30. The assembly is then rotated in a lathe while the portion 38 of the tube is heated until it softens and collapses on to the fibre. The assembly may be potted in a resin of R.I. lower than that of cladding 37 and tube 30. |
