| 摘要 |
PURPOSE:To eliminate the dependence upon polarization of characteristics, to remove restrictions from the number of stages of circuits, and to obtain excellent connectability to optical fibers by forming an optical coupling part by stretching of a dual core fiber to constitute a multistage Mach-Zehnder filter. CONSTITUTION:This fiber type optical equalizer is made of the dual core fiber where two cores different in propagation coefficients are formed in the sane clad with such distance between them that they are not optically coupled to each other. That is, plural parts in the lengthwise direction of the dual core fiber are stretched to produce 3dB couplers 4 and a 100% coupling coupler 5 as optical coupling parts between two cores, thus the optical equalizer is constituted of the multistage Mach-Zehnder filter. An optical signal is inputted from the first core placed in the center of the clad and is moved to the second core because of the existence of the 100% coupling coupler 5 in the input end and is inputted to the equalizer. The difference between propagation coefficients of two cores is used for the delay time difference, and this time difference is controlled by the length of the dual core fiber between couplers. |
