  Non-Hermitian systems at the exceptional point (EP) degeneracy are
demonstrated to be highly sensitive to environmental perturbation. Here, we
propose and theoretically investigate a novel multilayered heterostructure
favoring double EPs for a unique set of material parameters at which forward-
and backward-reflection coefficients vanish, respectively. Such an EP
heterostructure is shown to scatter off light when system parameters are
perturbed away from the degeneracies due to the effect of ambient temperature
and mechanical stress fluctuations. The proposed structure is conducive in
manipulating optical responses for two mutually independent parameters sensing.
