Theoretical investigation of a polymer Mach-Zehnder electro-optic switch using 2 N + 1 serial-coupled microrings with ultralow-driving voltage.

Universal structure and thorough analysis are proposed for a kind of (2 N + 1)th order polymer microring resonator Mach -Zehnder interferometer (MRR-MZI) electro-optic (EO) switch. Formulas and expressions of output power, insertion loss and crosstalk are derived, and detailed design and optimization are carried out. Analytical results indicate that, besides the first-order MRR-MZI EO switch ( N = 0), other devices for N ≥ 1 can all perform normal switching function, and 5 ≥ N ≥ 2 is preferred for dropping the crosstalk below −10 dB. For the four MRR EO switches ( N = 2-5), their switching voltages are 0.99, 0.73, 0.57 and 0.47 V, respectively; their insertion losses are within the range of 1.15-2.26 dB at bar state, whereas those are within the range of 1.95-2.42 dB at cross state; their crosstalks are within the range of 11.04-17.82 dB at bar state, whereas those are within the range of 10.34-12.51 dB at cross state. Compared with the traditional MZI EO switch, the voltage-length product (0.21 V mm) of this switching element is decreased by ~111.7 times under the same waveguide parameters. Therefore, due to small footprint size and extremely low switching voltage, this switching configuration can be densely integrated onto optoelectronic chips. [ABSTRACT FROM AUTHOR]