Symmetry-Broken Cavity Solitons and Collective Polarization Conformity in Fabry-Perot Kerr Resonators

Abstract

We report on the experimental generation of polarization symmetry-broken cavity solitons (CSs) in a passive, fiber-based, coherently-driven, Fabry-Perot (FP) Kerr resonator. Polarization resolved measurements reveal the spontaneous transition of initially symmetric CSs into asymmetrical vectorial states, triggered by a cross-phase modulation-induced polarization bifurcation. Most notably, due to counter-propagation of light occurring in FP resonators, we unveil a collective polarization conformity effect, whereby multiple CSs circulating in the cavity converge to the same asymmetric polarization state once their number exceeds a certain threshold. These results demonstrate that Fabry-Perot resonators support novel collective soliton dynamics that are absent in ring architectures.

Figures (6)

• Figure 1: (a) Bifurcation diagrams computed from Eqs. (\ref{['eq:LLEs']}), showing the intensity of homogeneous steady states (HSS) compared to SB-CSs for 1, 10, and 20 CSs circulating in the FP resonator. Unstable or non-stationary solutions are indicated by dashed lines. Parameters are $X = 11$ and $B = 1.2$. Panels (b--c) compare the intensity profiles of SB-CSs for a single CS ($\Delta = 10$) and for 20 CSs ($\Delta = 12.5$), respectively.
• Figure 2: Experimental setup. PPG: Pulse pattern generator, IM: Intensity modulator, PM: Phase modulators, AWG: arbitrary waveform generator, FG: Function generator, EDFA: Erbium doped fiber amplifiers, OBPF: Optical band-pass filter, PC: Polarization controllers, Att: Variable attenuator, Cir: Optical circulator, PBS: Polarizing beam splitters, PD: Photo-detectors, OSA: Optical spectrum analyzer, PDH: Pound–Drever–Hall. The inset shows a photo of the FP resonator mirrors.
• Figure 3: Nonlinear resonance measured for a driving peak power of 4 W. The purple curve shows the resonance along the driving polarization state ($x$), while the green curve displays the orthogonal (undriven) $y$-component. The blue curve is the total power, and the pink lines correspond to numerical simulations. The gray curve indicates the PDH signal used to lock the cavity at a specific detuning. The inset depicts the linear reflected response of the FP resonator, revealing that on resonance, up to $57\%$ of the input power is coupled into the cavity.
• Figure 4: (a) Evolution of a sequence of CSs over successive roundtrips, showing the writing of symmetric CSs followed by their bifurcation into symmetry-broken states (only the $I_-$ polarization component is represented for clarity purpose). (b, d) Temporal intensity profiles of symmetric and SB-CSs, respectively. (c) Ellipticity of the two first CSs shown in Panel (b) and (d) around the bifurcation point as highlighted by the dashed box in Panel (a) [dark blue dots: experimental data; pink dashed line: numerical simulations].
• Figure 5: Evolution of the polarization conformity ratio as a function of the number of CSs circulating in the FP resonator. Experimental data are shown as diamonds, while the pink solid line corresponds to numerical simulations. Insets (i-ii) display temporal traces of the CS sequence for 14 and 90 solitons circulating in the cavity, respectively.