One-volt silicon photonic crystal nanocavity modulator with indium oxide gate.

Author(s) Li, E.; Gao, Q.; Liverman, S.; Wang, A.X.
Journal Opt Lett
Date Published 2018 Sep 15

The ever-increasing global network traffic requires a high level of seamless integration between optical interconnect systems and complementary metal-oxide-semiconductor (CMOS) circuits. Therefore, it brings stringent requirements for future electro-optic (E-O) modulators, which should be ultracompact, energy efficient, high bandwidth, and in the meanwhile, able to be directly driven by the state-of-the-art CMOS circuits. In this Letter, we report a low-voltage silicon photonic crystal nanocavity modulator using an optimized metal-oxide-semiconductor (MOS) capacitor consisting of an InO/HfO/p-Si stacked nanostructure. The strong light-matter interaction from the accumulated free carriers with the nanocavity resonant mode results in holistic improvement in device performance, including a high tuning efficiency of 250 pm/V and an average modulation strength of 4 dB/V with a moderate Q factor of ∼3700 and insertion loss of ∼6  dB using an ultrashort electrode length of only 350 nm. With 1 V driving voltage over a capacitive loading of only 13 fF, the silicon photonic nanocavity modulator can achieve more than 3 dB extinction ratio with energy consumption of only 3 fJ/bit. Such a low-voltage, low-capacitance silicon nanocavity modulator provides the feasibility to be directly driven by a CMOS logic gate for single-chip integration.

DOI 10.1364/OL.43.004429
ISSN 1539-4794
Citation Opt Lett. 2018;43(18):44294432.

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