An Interleaver With Arbitrary Passband Width Ratio Based on Hybrid Structure of Microring and Mach–Zehnder Interferometer

In order to improve transmission efficiency of optical-fiber communication system for hybrid 10 G/40 G system presently, and hybrid 40 G/100 G system in the future, a planar lightwave circuit-based optical interleaver with arbitrary passband width ratio is proposed and investigated, which is based on hybrid structure of microring and Mach-Zehnder interferometer and offers the advantages of compactness, ruggedness, and better compatibility with other integrated optical circuits. Most importantly, the interleaver we proposed can realize the 3-dB passband width ratio between two output ports from equal to any unequal proportion just by adjusting coupling coefficients of couplers involved. The simulation results of symmetrical and asymmetrical output spectra are presented and all of them are with a channel isolation more than 45 dB and a flat-top passband. Furthermore, the effects of some key parameters on the characteristics of output spectra are also analyzed.