In Fig.8, Mach-Zehnder(MZ) type interferometers are depicted. The structure is situated in two dimensional photonic crystal with triangular lattice. To investigate interference at combining point, asymmetrical structure with different arm lengths are compared with symmetrical one. At first, electric field profile in symmetrical MZ structure is shown in Fig.9 The output characteristics of the asymmetric structure was investigated by experiment using a model in same microwave frequency range. The measurement results are shown in Fig.10.