The combination of high Q factor and chirality in twin cavities and microcavity chain

Abstract

Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities.

Frobenius–Perron eigenstates in deformed microdisk cavities: non-Hermitian physics and asymmetric backscattering in ray dynamics

“…Chirality means that the CCW and the CW components of the given eigenvector (3) are not of the same size. Hence, the optical modes are not standing waves but partially traveling waves [25,26,29,30], a fact that has been confirmed in a recent experiment [31]. Both eigenvectors(3) have the same dominant component and, therefore, both modes have the same preferred sense of rotation, i.e.…”

Experimental Demonstration of Spontaneous Chirality in a Nonlinear Microresonator

“…resonator, either by breaking the mirror [20][21][22][23][24] or timereversal [25][26][27] symmetry. Such chirality with unbalanced CW and CCW components not only attracts general interest in physics, but also is of importance in novel devices such as unidirectional-emission microlasers [18][19][20][21], optical gyroscopes [22,25,26], and single-particle detection [23,24]. In this Letter, we experimentally demonstrate the spontaneous emergence of a chiral optical field in a single ultrahigh-Q WGM microresonator ( Fig.…”

Non-Hermitian Hamiltonian and Lamb shift in circular dielectric microcavity

“…The Feshbach projection operator formalism yields non-Hermitian Hamiltonian, describing various kinds of interesting phenomena such as bi-orthogonality [10], phase rigidity [11], avoided resonance crossing [12][13][14], and exceptional points [15][16][17]. One prominent example is the Lamb shift.…”