Electromagnetically induced transparency at a chiral exceptional point

Abstract

Electromagnetically induced transparency, as a quantum interference effect to eliminate optical absorption in an opaque medium, has found extensive applications in slow light generation, optical storage, frequency conversion, optical quantum memory as well as enhanced nonlinear interactions at the few-photon level in all kinds of systems. Recently, there have been great interests in exceptional points, a spectral singularity that could be reached by tuning various parameters in open systems, to render unusual features to the physical systems, such as optical states with chirality. Here we theoretically and experimentally study transparency and absorption modulated by chiral optical states at exceptional points in an indirectly-coupled resonator system. By tuning one resonator to an exceptional point, transparency or absorption occurs depending on the chirality of the eigenstate. Our results demonstrate a new strategy to manipulate the light flow and the spectra of a photonic resonator system by exploiting a discrete optical state associated with specific chirality at an exceptional point as a unique control bit, which opens up a new horizon of controlling slow light using optical states. Compatible with the idea of state control in quantum gate operation, this strategy hence bridges optical computing and storage.

Induced Transparency with Optical Cavities

“…In 2020, Wang et al studied the induced transparency and absorption at a chiral EP, [215] which is achieved through positioning a nanotip within the vicinity of the cavity, resulting in perturbed evanescent fields and backscattering. Tuning the nanotip can modulate the chiral optical states in the left resonator from À1 (EP -) to 1 (EP þ ), resulting from hindering or allowing coupling between modes in two cavities.…”

“…[ 214 ] d) Phase‐invariant EPAA. [ 215 ] e) EPAT with different phase angle. [ 215 ] (a–c) Reproduced with permission.…”

“…[ 215 ] e) EPAT with different phase angle. [ 215 ] (a–c) Reproduced with permission. [ 214 ] Copyright 2018, APS.…”

Optothermal dynamics in whispering-gallery microresonators

“…Specifically, temperature fluctuation affects the material refractive index and the size of the resonator, both of which modify the mode distributions and shift the resonant frequencies of WGMs. Stable and continuous operation is critical for many applications, such as bio/chemical sensing [32][33][34][35][36][37][38][39][40][41][42] , optomechanics 19,[43][44][45] , microlaser [46][47][48][49][50][51] , non-Hermitian physics 15,20 , and nonlinear photonics 2,3,60,[52][53][54][55][56][57][58][59] . Taking WGM sensing as an example, resonance shifts induced by the target of interests 36 are typically mixed with the thermally induced mode shift.…”

Practical lineshape of a laser operating near an exceptional point

“…The exceptional point(EP) is a topological singular point in the parameter space at which two eigenstates coalesce due to non-Hermiticity [1]. It has recently attracted much attention in connection with many applications and fundamental issues such as directionality [2], non-adiabaticity [3,4], fractional topological charges [5], anti-parity-time symmetric EP [6], phonon lasing [7] and electromagnetically induced transparency at an EP [8]. Another important issue is utilizing the EP to enhance the performance of a sensor [9,10].…”