为了在10 Gb/s+40 Gb/s混合系统中提高光学奇偶交错滤波器的带宽利用率,提出了基于两级级联马赫曾德尔干涉仪(MZI)的全光纤型不等带宽光学交错滤波器的设计方案。通过对耦合器分光比、干涉仪臂长差等结构参量的选择,详细分析了两级级联MZI的不等带宽交错滤波器的传输特性,并选取了理论优化计算的一组数据进行实验。 数值分析和实验结果表明,该器件将50 GHz的输入信号分离成信道间隔为100 GHz的奇偶两路输出信号,其中在3 dB处,奇数信道带宽大于30 GHz用于10 Gb/s传输,偶数信道带宽大于60 GHz用于40 Gb/s传输。该滤波器较传统的等带宽交错滤波器有更高的带宽利用率,在10 Gb/s向10 Gb/s+40 Gb/s升级过程中作为复用/解复用器具有很大优势。

To improve the utilization efficiency of interleaver bandwidth in 10 Gb/s plus 40 Gb/s hybrid system,an all-fiber asymmetric bandwidth optical interleaver based on a cascaded Mach-Zehnder interferometer is proposed and discussed.Influences on its transmission characteristics by such factors as splitting ratio of the coupler of the directional fiber couplers and the physical length differences of the interferometer arms are numerically analyzed in detail.The preference condition of the interleaver which meets the maximal isolation and the characteristic of the output spectrum is obtained.One set of optimized data is validated in the experimental result.The results of numerical simulation and experiments show that all-fiber optical interleaver with -3 dB passband in odd channels and even channels could be obtained,which have more than 60 GHz passband and 30 GHz passband,for transmission speed of 40 Gb/s and 10 Gb/s,respectively.Experimental results are in good agreement with the simulation results.Comparing with the conventional interleaver with uniform bandwidth channel,the kind of interleaver with higher bandwidth utilization efficiency has more advantages as multiplexer/demultiplexer during upgrade from 10 Gb/s to 10 Gb/s+40 Gb/s.