  As the diffraction limit is approached, device miniaturization to integrate
more functionality per area becomes more and more challenging. Here we propose
a novel strategy to increase the functionality-per-area by exploiting the modal
properties of a waveguide system. With such approach the design of a
mode-multiplexed nanophotonic modulator relying on the mode-selective
absorption of a patterned Indium-Tin-Oxide is proposed. Full-wave simulations
of a device operating at the telecom wavelength of 1550nm show that two modes
can be independently modulated, while maintaining performances in line with
conventional single-mode ITO modulators reported in the recent literature. The
proposed design principles can pave the way to a novel class of
mode-multiplexed compact photonic devices able to effectively multiply the
functionality-per-area in integrated photonic systems.
