Controllable multiple beam splitting in Hermitian and non-Hermitian symmetric coupled waveguide systems

Abstract

We investigate high-fidelity multiple beam splitting in Hermitian and non-Hermitian (NH) symmetric coupled waveguides (WGs) with one input and 2 N output WG channels. In Hermitian systems, we realize adiabatically light splitting in resonant case based on the stimulated Raman adiabatic passage and arbitrary proportion from the middle WG to outer WGs in propagation coefficients mismatch case using shortcuts to adiabaticity (STA) technique. In NH systems with even WGs being dissipative, the compact and robust beam splitting can be achieved by eliminating the non-adiabatic coupling via the NH STA method. We further verify the feasibility of our theoretical predictions by means of the beam propagation method. The suggested multiple beam splitters open new opportunities for the realization of on-chip high-bandwidth photonics with high fidelity in short distances.