  Exceptional points (EPs) are degeneracies in open wave systems with
coalescence of at least two energy levels and their corresponding eigenstates.
In higher dimensions, more complex EP physics not found in two-state systems is
observed. We consider the emergence and interaction of multiple EPs in a four
coupled optical waveguides system by non-Hermitian coupling showing a unique EP
formation pattern in a phase diagram. In addition, absolute phase rigidities
are computed to show the mixing of the different states in definite parameter
regimes. Our results could be potentially important for developing further
understanding of EP physics in higher dimensions via generalized paradigm of
nonHermitian coupling for a new generation of parity-time (PT) devices.
