Design and identification of a double-acting piezoelectric-hydraulic hybrid actuator

Traditional single-acting piezoelectric-hydraulic hybrid actuators usually have the problem of inertial force caused by flow pulsation of the liquid,which degrades their output performance.To suppress or solve the associated inertial force and enhance its output capabilities,this paper proposes a new type of double-acting piezoelectric-hydraulic hybrid actuator with four check valves acting as mechanical diodes.The new hybrid actuator was fabricated and its output performance was tested.When the voltage is 700 Vp-pand the bias pressure is 2 MPa,the pulsation ratesδof the new actuator at 400 Hz,500 Hz and 600 Hz are 2.29,2.08 and 1.78,respectively,whileδof the single-acting hybrid actuator under the same conditions are 10.98,11.05 and 17.12.Therefore,the liquid pulsation rate of the new hybrid actuator is significantly reduced,which is beneficial for improving the flow uniformity and weakening the influence of inertial force on the hybrid actuator.This strategy ultimately leads to a maximum no-load velocity of 168.1 mm/s at 600 Hz and a maximum blocking force of 141 N at 450 Hz for the new hybrid actuator.In addition,this strategy has the potential to be used in other electrohydrostatic actuators to improve their performance.

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%.