Mid-infrared Electro-Optic Modulation in Few-layer Black Phosphorus

Abstract

Black phosphorus stands out from the family of two-dimensional materials as a semiconductor with a direct, layer-dependent bandgap in energy corresponding to the spectral range from the visible to the mid-infrared (mid-IR), as well as many other attractive optoelectronic attributes. 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 been proven to be a viable alternative. Here, we demonstrate electro-optic modulation of mid-IR absorption in few-layer black phosphorus under field applied by an electrostatic gate. 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. Spectroscopic study on samples with varying thickness reveals strong layer-dependence in the inter-band transition between different sub-bands. Our results show black phosphorus is a very promising material to realizing efficient mid-IR modulators.

References in corpus (11)

• Boron nitride substrates for high-quality graphene electronics
• Two-Dimensional Material Nanophotonics
• Graphene photodetectors for high-speed optical communications
• Effective Passivation of Exfoliated Black Phosphorus Transistors against Ambient Degradation
• The Renaissance of Black Phosphorus
• Broadband Linear-Dichroic Photodetector in a Black Phosphorus Vertical p-n Junction
• Waveguide-integrated black phosphorus photodetector with high responsivity and low dark current
• Tunable optical properties of multilayers black phosphorus thin films
• Infrared fingerprints of few-layer black phosphorus
• High-speed waveguide-coupled graphene-on-graphene optical modulators
• Field Effect Optoelectronic Modulation of Quantum-Confined Carriers in Black Phosphorus