| 摘要 |
A low-loss optical 1 x 2 branching element comprises a symmetrical coupler (Cs) with a symmetrical power distribution (1/2 /1/2 ) and an asymmetric coupler (Ca)with an asymmetric power distribution (ä(1/2 - x)/(1/2 + x)ü). Outputs (c,d) of the symmetrical coupler are coupled to inputs (e,f) of the asymmetric coupler, so that an MZ interferometer with two branches (t1,t2) is formed between the two couplers. The branches incorporate, preferably identical, optical non-linear elements (NL1,NL2), while moreover the branches exhibit an additional difference in linear optical path length ( DELTA L) that depends on the type of couplers selected. In one signal direction (arrow D) the branching element acts as a 3 dB splitter. The elements (NL1,NL2) and the coupler (Ca) have been dimensioned so as to result in a loss << 3 dB for a given signal power in the other signal direction (arrow U). <IMAGE> |
