| 摘要 |
PROBLEM TO BE SOLVED: To constitute an MZ interferometer in such a manner that the two waveguide branches thereof have a difference in optical path lengths to compensate the phase characteristic of a power splitter and/or coupler of a selected type. SOLUTION: The low-loss 1×2 optical branch element consists of a symmetrical coupler (Cs) having symmetrical power distribution (1/2/1/2) and an asymmetrical coupler (Ca) having asymmetrical power distribution ( (1/2-x)/(1/2+x)}). The outputs (c, d) of the symmetrical coupler are coupled to the inputs (e, f) of the asymmetrical coupler and, therefore, the MZ interferometer is formed by having the two branches (t1 , t2 ) between these two couplers. These branches are preferably joined to the same optical nonlinear elements (NL1 , NL2 ) and further, the branches denote the linear optical path length difference (ΔL) dependent on the type of the selected couplers. the branch element acts as a 3dB splitter in one signal direction (arrow D). The sizes of the elements (NL1 , NL2 ) and the coupler (Ca) are so determined that the loss is much smaller than 3dB with respect to the signal power given by another signal direction (arrow U). |
