Low Half-Wave Voltage in Hybrid Silicon/Polymer Waveguide Modulators for ECG Signal Acquisition

As an electro-optic signal modulation device, the Mach-Zehnder (MZ) electro-optic modulator has potential applications in electrocardiogram (ECG) weak signal modulation. We propose a hybrid silicon/polymer asymmetric MZ electro-optic modulator that has the advantages of low half-wave voltages and low loss. The proposed modulator functions in the 1550 nm band, and it is mainly composed of two 3 dB multimode interference couplers, a bent waveguide, a modulation waveguide and a phase shifter. The loss of the multimode interference coupler is −0.43 dB at a device size of 4 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times19.3\,\,\mu \text{m}$ </tex-math></inline-formula>. The core device size is 160 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times700\,\,\mu \text{m}$ </tex-math></inline-formula>. The initial working state of the modulator is in the linear region, which can directly realize the linear modulation of voltage. Under the simulation condition of <inline-formula> <tex-math notation="LaTeX">$\gamma _{33} =18.3$ </tex-math></inline-formula> pm/V, the results show that the modulator has a low loss of −3.4 dB and a low half-wave voltage amplitude of 3.0 V.