| 摘要 |
PCT No. PCT/GB91/00453 Sec. 371 Date Nov. 24, 1992 Sec. 102(e) Date Nov. 24, 1992 PCT Filed Mar. 26, 1991 PCT Pub. No. WO91/14963 PCT Pub. Date Oct. 3, 1991.An optical apparatus including a first optical coupling having a first and a second pair of optical communication ports in which substantially equal portions of an optical signal received at a port of one pair of ports are coupled to each port of the other pair of ports; an optical waveguide optically coupling the second pair of ports such that an optical signal leaving either one of the second pair of ports in a first polarization state; a second optical coupling for coupling an optical signal at a second wavelength to the optical waveguide so as to propagate along at least a portion of it in one direction only; and first and second polarizing beam splitters optically coupled to a respective one of the first pair of ports. |
