| Summary: | Towards realizing highly integrable low-energy optical modulators, the small device capacitance
(C) as well as the low driving voltage (Vpp)
is demanded for suppressing the charging energy during the dynamic operation. Although an
electro-absorption modulator (EAM) has great potential in reducing them, the additional
energy
associated with the photocurrent flow will limit the lower-bound of the consumption
energy. In this
work, a broadband EAM based on an InGaAsP-embedded photonic crystal waveguide is
demonstrated, revealing a high modulation bit rate of up to 56 Gbit/s. The air-bridge
structure and a device length of 100 μm or less result in a small
C ≤ 13 fF while operating with Vpp < 1
V. Particularly, the operation in low reverse voltage for a p-i-n junction, that is, −0.2
V as the minimum value in this study, works effective for the reduction of energy involving the
photocurrent.
This results in the total electrical energy consumption of <2 fJ/bit, which is lower than
that of any waveguide EAMs.
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