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Midinfrared Electro-optic Modulation in Few-Layer Black Phosphorus
journal contribution
posted on 2017-09-27, 00:00 authored by Ruoming Peng, Kaveh Khaliji, Nathan Youngblood, Roberto Grassi, Tony Low, Mo LiBlack
phosphorus stands out from the family of two-dimensional
materials as a semiconductor with a direct, layer-dependent bandgap
spanning the visible to mid-infrared (mid-IR) spectral range. It is,
therefore, a very promising material for various optoelectronic applications,
particularly in the important mid-IR range. While mid-IR technology
has been advancing rapidly, both photodetection and electro-optic
modulation in the mid-IR rely on narrow-band compound semiconductors,
which are difficult and expensive to integrate with the ubiquitous
silicon photonics. For mid-IR photodetection, black phosphorus has
already been proven to be a viable alternative. Here, we demonstrate
electro-optic modulation of mid-IR absorption in few-layer black phosphorus.
Our experimental and theoretical results find that, within the doping
range obtainable in our samples, the quantum confined Franz–Keldysh
effect is the dominant mechanism of electro-optic modulation. A spectroscopic
study on samples with varying thicknesses reveals strong layer dependence
in the interband transition between specific pairs of sub-bands. Our
results show that black phosphorus is a very promising material to
realizing efficient mid-IR modulators.