2020/07/01 by Sun‐Goo Lee, Lee, Sun-Goo, Seong‐Han Kim +3 · 1 citation
Physics and Astronomy · #Nonlinear Photonic Systems #Advanced Fiber Laser Technologies #Quantum optics and atomic interactions
paper · pdf · doi:10.48550/arxiv.2007.00371
When two nonorthogonal resonances are coupled to the same radiation channel,\navoided crossing arises and a bound state in the continuum (BIC) appears in\nparametric space. This paper presents numerical and analytical results on the\nproperties of avoided crossing and BIC due to the coupled guided-mode\nresonances in one-dimensional leaky-mode photonic lattices with slab geometry.\nIn symmetric photonic lattices with up-down mirror symmetry, Friedrich-Wintgen\nBICs with infinite lifetime are accompanied by avoided crossings due to the\ncoupling between two guided modes with the same transverse parity. In\nasymmetric photonic lattices with broken up-down mirror symmetry, quasi-BICs\nwith finite lifetime appear with avoided crossings because radiating waves from\ndifferent modes cannot be completely eliminated. We also show that\nunidirectional-BICs are accompanied by avoided crossings due to guided-mode\nresonances with different transverse parities in asymmetric photonic lattices.\nThe Q factor of a unidirectional-BIC is finite, but its radiation power in the\nupward or downward direction is significantly smaller than that in the opposite\ndirection. Our results may be helpful in engineering BICs and avoided crossings\nin diverse photonic systems that support leaky modes.\n