  On-chip mode division (de)multiplexing plays a significant role in the
integrated devices to greatly improve communication capacity. One of the
pursuing goals of mode division (de)multiplexer is how to realize such devices
with larger bandwidth and better fabrication tolerance. However, integrated
broadband mode division (de)multiplexing devices were rarely reported up to
now. In this work, we experimentally realize a broadband mode division
demultiplexing device with a high degree of fabrication tolerance based on
lithium niobate-on-insulator waveguide array. By taking advantage of the fact
that different modes in the waveguide array have different group velocity, we
experimentally confirmed that different modes in the waveguide array have
different transverse displacements. The implementation of the integrated
broadband mode division demultiplexer may have future applications in
information processing technology, quantum communication as well as quantum
computing.
