56 Gbps high-speed Ge electro-absorption modulator
Zhi Liu, Xiuli Li, Chaoqun Niu, Jun Zheng, Chunlai Xue, Yuhua Zuo, Buwen Cheng
Abstract
A high-speed evanescent-coupled Ge waveguide electro-absorption modulator (EAM) with simple fabrication processes was realized on a silicon-on-insulator platform with a 220 nm top Si layer. Selectively grown Ge with a triangle shape was directly used for Ge waveguides of the EAM. An asymmetric p-i-n junction was designed in the Ge waveguide to provide a strong electric field for Franz–Keldysh effect. The insertion loss of the Ge EAM was 6.2 dB at 1610 nm. The EAM showed the high electro-optic bandwidth of 36 GHz at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:mo form="prefix">−</mml:mo> <mml:mn>1</mml:mn> <mml:mtext> </mml:mtext> <mml:mi mathvariant="normal">V</mml:mi> </mml:mrow> </mml:math> . Clear open 56 Gbps eye diagrams were observed at 1610 nm with a dynamic extinction ratio of 2.7 dB and dynamic power consumption of 45 fJ/bit for voltage swing of 3 V pp .