Integrated germanium-on-silicon Franz-Keldysh vector modulator used with a Kramers-Kronig receiver

Abstract

We propose an integrated vector modulator based on two compact and high-speed germanium-on-silicon Franz Keldysh electro-absorption modulators. The proposed vector modulator is extremely compact with a total footprint of only 1800 mu m x 200 mu m. We further experimentally demonstrate a 4-quadrature-amplitude-modulation (4-QAM) at 40 Gb/s over a 20-km standard single-mode fiber transmission. The complex signal is successfully reconstructed with a single-ended photodiode in a recently proposed Kramers-Kronig receiver for future low-cost, low-power, and low-footprint datacenter interconnect applications. The preliminary performance of the vector modulator with a 16-QAM is also investigated. (c) 2018 Optical Society of America.