Modeling and optimization of a single-drive push–pull silicon Mach–Zehnder modulator

We present an equivalent circuit model for a silicon carrier-depletion single-drive push–pull Mach–Zehnder modulator(MZM)with its traveling wave electrode made of coplanar strip lines.In particular,the partialcapacitance technique and conformal mapping are used to derive the capacitance associated with each layer.The PN junction is accurately modeled with the fringe capacitances taken into consideration.The circuit model is validated by comparing the calculations with the simulation results.Using this model,we analyze the effect of several key parameters on the modulator performance to optimize the design.Experimental results of MZMs confirm the theoretical analysis.A 56 Gb/s on–off keying modulation and a 40 Gb/s binary phase-shift keying modulation are achieved using the optimized modulator.

Silicon high-speed binary phase-shift keying modulator with a single-drive push–pull high-speed traveling wave electrode

We demonstrate binary phase shift keying(BPSK) modulation using a silicon Mach–Zehnder modulator with aπ-phase-shift voltage(Vπ) of-4.5 V.The single-drive push–pull traveling wave electrode has been optimized using numerical simulations with a 3 dB electro-optic bandwidth of 35 GHz.The 32 Gb/s BPSK constellation diagram is measured with an error vector magnitude of 18.9%.

新凉水塔风机振动问题的治理

针对凉水塔风机振动较大，提出了从电机开始逐级单试，解决国产凉水塔风机振动的一种行之有效的方法。