TY - JOUR
T1 - Device Architectures for Low Voltage and Ultrafast Graphene Integrated Phase Modulators
AU - Mao, Dun
AU - Cheng, Chen
AU - Wang, Feifan
AU - Xiao, Yahui
AU - Li, Tiantian
AU - Chang, Lorry
AU - Soman, Anishkumar
AU - Kananen, Thomas
AU - Zhang, Xian
AU - Krainak, Michael
AU - Dong, Po
AU - Gu, Tingyi
N1 - Publisher Copyright:
© 2020 IEEE.
PY - 2021/3
Y1 - 2021/3
N2 - The atomic layer thin geometry and semi-metallic band diagram of graphene can be utilized for significantly improving the performance matrix of integrated photonic devices. Its semiconductor-like behavior of Fermi-level tunability allows graphene to serve as an active layer for electro-optic modulation. As a low loss metal layer, graphene can be placed much closer to active layer for low voltage operation. In this work, we investigate hybrid device architectures utilizing semiconductor and metallic properties of the graphene for ultrafast and energy-efficient electro-optic phase modulators on semiconductor and dielectric platforms. (1) Directly contacted graphene-silicon heterojunctions. Without the oxide layer, the carrier density of graphene can be modulated by direct contact to silicon layer, while silicon intrinsic region stays mostly depleted. With doped silicon as electrodes, carriers can be quickly injected and depleted from the active region in graphene. The ultrafast carrier transit time and small RC constant promise ultrafast modulation speed (3 dB bandwidth of 67 GHz) with an estimated Vπ·L of 1.19 V·mm. (2) Graphene integrated lithium niobite modulator. As a transparent electrode, graphene can be placed close to integrated lithium niobate waveguide for improving coupling coefficient between optical mode profile and electric field with minimal additional loss (4.6 dB/cm). Numerical simulation indicates a 2.5× improvement of electro-optic field overlap coefficient, with an estimated Vπ of 0.2 V.
AB - The atomic layer thin geometry and semi-metallic band diagram of graphene can be utilized for significantly improving the performance matrix of integrated photonic devices. Its semiconductor-like behavior of Fermi-level tunability allows graphene to serve as an active layer for electro-optic modulation. As a low loss metal layer, graphene can be placed much closer to active layer for low voltage operation. In this work, we investigate hybrid device architectures utilizing semiconductor and metallic properties of the graphene for ultrafast and energy-efficient electro-optic phase modulators on semiconductor and dielectric platforms. (1) Directly contacted graphene-silicon heterojunctions. Without the oxide layer, the carrier density of graphene can be modulated by direct contact to silicon layer, while silicon intrinsic region stays mostly depleted. With doped silicon as electrodes, carriers can be quickly injected and depleted from the active region in graphene. The ultrafast carrier transit time and small RC constant promise ultrafast modulation speed (3 dB bandwidth of 67 GHz) with an estimated Vπ·L of 1.19 V·mm. (2) Graphene integrated lithium niobite modulator. As a transparent electrode, graphene can be placed close to integrated lithium niobate waveguide for improving coupling coefficient between optical mode profile and electric field with minimal additional loss (4.6 dB/cm). Numerical simulation indicates a 2.5× improvement of electro-optic field overlap coefficient, with an estimated Vπ of 0.2 V.
KW - Graphene
KW - Lithium Niobate
KW - Mach-Zehnder interferometer
KW - p-n junction
KW - phase modulator
KW - silicon photonics
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U2 - 10.1109/JSTQE.2020.3026357
DO - 10.1109/JSTQE.2020.3026357
M3 - Article
AN - SCOPUS:85178010394
SN - 1077-260X
VL - 27
JO - IEEE Journal of Selected Topics in Quantum Electronics
JF - IEEE Journal of Selected Topics in Quantum Electronics
IS - 2
M1 - 3400309
ER -