Counterpropagating light in ring resonators: Switching fronts, plateaus, and oscillations

Abstract

We characterise the formation of robust stationary states formed by light plateaus separated by two local switching fronts in only one of two counterpropagating fields in ring resonators with normal dispersion. Such states are due to global cross coupling and allow for frequency combs to switch from one field to the other by simply tuning the input laser frequency. Exact expressions for the distance between fronts and for plateau powers are provided in excellent agreement with simulations. These demonstrate an unusual high degree of control over pulse and plateau duration in one of the fields upon changes of one of the input laser frequencies. We identify a wide parameter region in which light plateaus are self-starting and are the only stable solution. For certain values of the detunings we find multi-stable states of plateaus with switching fronts, slowly oscillating homogeneous states and non-oscillating homogeneous states of the counterpropagating fields. Robustness and multi-stability of these unusual single-field front solutions are provided in parameter ranges that are experimentally achievable in a wide variety of ring resonators.

Symmetry Broken Vectorial Kerr Frequency Combs from Fabry-Pérot Resonators

“…Equation ( 3) is identical in its mathematical form, although not physical meaning, to the homogeneous stationary states of two linearly polarised fields counter-propagating a Kerr ring resonator [6,7,10,35], or of two orthogonally polarized fields co-propagating a Kerr ring resonator [11,16,36]. Due to its mathematical analogies to other such systems, Eq.…”

“…Although one of their effects has already been felt, the requirement to analyse separately the n = 0 stability eigenvalues, their wider effects have remained somewhat hidden until this section. We have stated that, mathematically, these angled terms amount to an average of the field intensity profiles across the cavity, but owed to this they cause a global coupling across the cavity [35]. Related to the TCS pairs, these global coupling terms effectively mean that all the soliton pairs feel the impact of, and in turn influence, any others in the cavity.…”

“…One can also see that these ⟨f ⟩ terms further have the effect of raising the cavity detuning value at which the solitons gain viability. This is because the ⟨f ⟩ terms cause an effective detuning in the system [24,35]. Further still, one notes that the more solitons present in the cavity, the more by which this detuning limit is raised.…”

Quintic Dispersion Soliton Frequency Combs in a Microresonator

“…Bright solitons can be described to originate from modulation instability, [4] in contrast to dark solitons, which arise through the interlocking of switching waves connecting the homogenous steady-states of the bistable cavity system. [15,16] Recent research theoretically predicted the coexistence of bright and dark solitons in the regimes of normal, [17] zero, [18][19][20] and anomalous GVD, [21] when taking account of higher-order dispersion (thirdand fourth-order).…”

Real-time imaging of standing-wave patterns in microresonators

“…They have been responsible for recent advances in applications such as comb generation ( 3 – 8 ), on-chip lasers ( 9 – 11 ), biomedical sensing ( 12 – 18 ), and optical communications ( 19 – 21 ). In a lot of applications, backscattering and the resulting generation of standing waves generated inside a microresonator is a topic of great interest ( 22 – 27 ). It can not only promote our understanding of fundamental physics, such as strong coupling between the atom and microcavity ( 28 ), symmetry breaking phenomena, ( 29 – 33 ) and cavity quantum electrodynamics (cavity QED) ( 34 , 35 ), but also be a fascinating tool to realize various applications ( 36 , 37 ).…”