Effect on Kerr comb generation in a clockwise and counter-clockwise mode coupled microcavity

Abstract

We study the impact of inherent mode coupling between clockwise (CW) and counter-clockwise (CCW) modes on Kerr comb generation in a small whispering-gallery mode microcavity. Our numerical analysis using a coupled Lugiato-Lefever equation reveals the range of the coupling strength in which a soliton pulse can be obtained in the CW direction. It also showed that CCW comb power depends on the coupling strength between the CW and CCW modes. In addition to the simulation, we conducted an experiment to confirm that the power ratio between the CW and CCW comb modes depends on the coupling strength, and the experimental results agree well with the simulation results. This study helps us to understand the relationship between CW and CCW mode coupling and Kerr comb generation, and the effect on soliton formation.

Modulational instability and frequency combs in whispering-gallery-mode microresonators with backscattering

“…It can be also shown that the sign in the linear interaction term argument is a consequence of the cylindrical symmetry. Note, that similar equations were used in [27,28], but the signs in the argument of the linear coupling term are different and nonlinear cross-action terms are absent or depend on the local intensity values instead of the averaged values. Our calculations show that these differences may affect the boundaries of soliton existence and stability domains at anomalous GVD.…”

“…Also frequency comb generation at normal group velocity dispersion (GVD) was demonstrated in case of the coupling between different co-propagating spatial or polarizational mode families existing simultaneously in the microresonators [22][23][24]. Recently a number of results on the impact of the linear and nonlinear couplings between the counter-propagating waves has been reported [25,26] including generation of DKS [27][28][29]. However, the absence of the consistency and transparent justification of the applied models call for a revision of this problem in * noxobar@mail.ru the view of its persistent importance for practical applications.…”

Bloch-Floquet waves in optical ring resonators

“…A characteristic feature of RRs is the splitting of modal resonances due to scattering of a propagating wave into a frequencydegenerate counter-propagating one. Due to its implications for optical device performance [16], modal coupling in ring resonators has been the subject of intensive study, having previously been described via several robust approaches including steady state loop equations [17], temporal Coupled Mode Theory [18][19][20][21][22][23], and the transfer matrix method [24,25]. While these approaches are very useful, they are usually limited to analyzing the splitting of a single mode.…”

“…16) Provided the dispersion relation is approximately linear (i.e. ω c √ κ 0 k), then these two terms will dominate the expansion whenever k ± 2πl P .…”

Transition between Kerr comb and stimulated Raman comb in a silica whispering gallery mode microcavity

“…6(a). The pumped resonance exhibits a slight mode splitting due to backscattering of light [41]. We coupled the CW input to the microcavity with a tapered optical fiber setup, where the transmitted optical power and the output spectrum were recorded with a power meter and an optical spectrum analyzer.…”