High-Speed Silicon Modulator With Slow-Wave Electrodes and Fully Independent Differential Drive

Abstract

We demonstrate a fully independent differential-drive capable of traveling-wave modulator in silicon using slow-wave transmission line electrode. The reported 3.5-mm device achieves a bandwidth of 27 GHz at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math> $-$</tex-math></inline-formula> 1 V bias with 7.8-V small signal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math>$V_\pi$</tex-math> </inline-formula> and 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math>$\Omega$</tex-math></inline-formula> impedance. Raising the impedance to this extent requires effectively expanding the RF mode size and radically changes the RF phase velocity, but we show that this can be done with minimal crosstalk effects between the two arms and overall velocity mismatch, and thus, with a high EO bandwidth achieved. 40-Gb/s operation is demonstrated with 1.6-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> differential-drive, and performance comparisons to Lithium Niobate modulators are made.