Optimization design of all-fiber 3 × 3 multiplexer based on an asymmetrical Mach-Zehnder interferometer

All-fiber 3 × 3 multiplexer based on an asymmetrical Mach-Zehnder Interferometer has been analyzed theoretically, which is made of a fused planar 3 × 3 and a fused triangular 3 × 3 single mode fiber coupler. The mathematical description is provided. The variation in the channel crosstalk at the output port due to the lateral deviation of the splitting ratios of the couplers are studied. Comparing with the three-fiber 3 × 3 multiplexer using two the triangular 3 × 3 fiber coupler, the reduced sidelobe level of channel of the proposed device is more than 13.6 dB, and the proposed device has better crosstalk characteristics when the same lateral deviation of the power splitting ratio is introduced. Analysis and experiment show that there is a relative high success rate of fabricating an all-fiber 3 × 3 multiplexer by using proposed configuration and design approach. The experiment results are in good agreement with the analytical ones. The result shows that the measured sidelobe level is about −34.6 dB, the insertion loss is less than 1.0 dB and channel isolation is higher than 30 dB, respectively.