Michelle
C. Sherrott, William S. Whitney, Deep Jariwala,
Souvik iswas, Cora Went, Joeson Wong, George R. Rossman, Harry A. Atwater
California Institute of Technology
Pasadena, CA 91125-2500
Abstract
The incorporation of electrically tunable materials into photonic
structures such as waveguides and metasurfaces enables dynamic control
of light propagation by an applied potential. While many materials have
been shown to exhibit electrically tunable permittivity and dispersion,
including transparent conducting oxides (TCOs) and III-V semiconductors
and quantum wells, these materials are all optically isotropic in the
propagation plane. In this work, we report the first known
example of electrically-tunable linear dichroism, observed here in
few-layer black phosphorus (BP), which is a promising candidate for
multi-functional, broadband, tunable photonic elements. We measure
active modulation of the linear dichroism from the mid-infrared to
visible frequency range, which is driven by anisotropic
quantum-confined Stark and Burstein-Moss effects, and field-induced
forbidden-to-allowed optical transitions. Moreover, we observe
high BP absorption modulation strengths, approaching unity for certain
thicknesses and photon energies.