A photonic integrated circuit includes a photonic device. The photonic device includes an input region configured to receive an input signal including a plurality of multiplexed channels. The photonic device includes a metastructured dispersive region structured to partially demultiplex the input signal into an output signal and a throughput signal. The output signal includes a channel of the multiplexed channels. The throughput signal includes the remaining channels of the multiplexed channels. The photonic device includes an output region and a throughput region optically coupled with the metastructured dispersive region to receive the output signal and the throughput signal, respectively. The metastructured dispersive region includes a heterogeneous distribution of a first material and a second material that structures the metastructured dispersive region to partially demultiplex the input signal into the output signal and the throughput signal.