Determination of complex Hermitian and anti-Hermitian interaction constants from a coupled photonic system via coherent control.

By manipulating the relative amplitude and phase between two incoming lights, coherent control of photonic systems can be realized. Here, we show by temporal coupled mode theory and finite-difference time-domain simulation that a coupled system can be actively controlled to exhibit plenty of different spectral, angular, and excitation behaviors. Electromagnetically induced transparency-like and Fano spectral characteristics as well as strong beam steering have been observed. Remarkably, by selectively exciting the coupled modes, we have developed a new approach to determine the complex Hermitian and anti-Hermitian interaction constants. We find the constants are strongly geometric and material dependent and they are of importance in understanding the non-Hermitian physics arising from the dissipative, open coupled system.