Large Sagnac frequency splitting in a ring resonator operating at an exceptional point

Abstract

In rotating ring resonators, resonant frequencies are split because of the Sagnac effect. The rotation sensitivity of the frequency splitting characterizes the sensitivity of resonator-based optical gyroscopes. In this paper, it is shown that the sensitivity of frequency splitting can be significantly enhanced in a ring resonator operating at an exceptional point (EP), which is a non-Hermitian degeneracy where two eigenvalues and the corresponding eigenmodes coalesce. As an example, a ring resonator with a periodic structure is proposed and theoretically and numerically studied. It is numerically demonstrated that in the resonator operating near an EP, the rotation-induced frequency splitting can be more than two orders greater than that in conventional ring resonators. In addition, this paper discusses the influence of the resonator loss on the measurement sensitivity of the frequency splitting and a method of rotation detection based on rotation-induced changes of eigenmodes near an EP.

Enhanced response of non-Hermitian photonic systems near exceptional points

“…The response theory presented in this work is applicable to a variety of photonic systems, including optical microcavities, parity-time symmetric systems, optomechanical resonators, and plasmonic systems that can operate at an EP. The response characteristics at an EP shown in this work, e.g., the enhancement in or suppression of the response amplitude, will be useful for controlling the excitation of eigenmodes, the output from resonator sensors at EPs [37][38][39][40], extraordinary optical transmission [59], or the light-matter interactions inside microcavities.…”

Loschmidt Echo and Fidelity Decay Near an Exceptional Point

“…Such a result stems from the fact that, if the Hamiltonian depending on a control parameter h shows an EP at , then the energy spectrum and corresponding eigenfunctions are non‐analytic and show a branch point at h 0 , with . The strong sensitivity to perturbations is at the heart of several phenomena studied in recent works, such as sensing enhancement in optical micro cavities, cavity‐assisted enhanced metrology and quantum sensing, ultra‐sensitive micro‐scale gyroscopes, quantum and photonic catastrophes, critical phenomena, and dynamical quantum phase transitions . A related phenomenon observed as the parameter h is slowly cycled around an EP is the asymmetric breakdown of the adiabatic theorem and unidirectional transitions, resulting in topological energy transport and asymmetric mode switching …”

Collectively induced exceptional points of quantum emitters coupled to nanoparticle surface plasmons

“…We note, however, that the true applicability and usefulness of EP sensing depend on the details of how the parametric change is measured [8,11]. In any case, finding practically useful EPs in physically accessible systems [12][13][14] and parameter regimes is still an open problem [15][16][17], and a range of candidates have been studied, such as parity-timesymmetric systems [12,[18][19][20][21][22][23][24][25], coupled atom-cavity systems [26], microcavities [12,20,21,[27][28][29], microwave cavities [30][31][32][33], acoustic systems [34], photonic lattices [19,35], photonic crystal slabs [36], exciton-polariton billiards [37], plasmonic nanoresonators [38], ring resonator [39], optical resonators [40][41][42], and topological arrangements [37]. However, the typical size of these systems possessing EPs is usually too large (of several hundred nanometers) to be utilized for sensing in some important applications.…”