Test robustness of proposed Kerr-isolator circumvention schemes

Test whether proposed Kerr-based schemes that circumvent dynamic reciprocity remain robust to arbitrary weak backward perturbations, coherent phase, detuning, and backscattering under simultaneous forward and backward excitation.

Background

The review explains that passive Kerr and Kerr-like isolators are subject to dynamic reciprocity: a weak backward probe cannot generally be completely suppressed while a strong forward signal is continuously present. It then describes proposed schemes intended to circumvent this limitation, including designs based on direction-dependent self-phase and cross-phase modulation.

For these proposals, the review notes that the available evidence is based on coupled-mode and finite-difference time-domain simulations rather than experimental validation. Their robustness under arbitrary weak reverse perturbations, variations in coherent phase and detuning, and backscattering therefore remains unresolved.

References

The evidence is coupled-mode/FDTD simulation rather than an experimental demonstration, and robustness to an arbitrary weak backward perturbation, coherent phase, detuning, and backscattering remains to be tested.

— On-chip optical isolators  (2610.17862 - Mikhail et al., 13 Oct 2026) in Section 5, subsection “Kerr nonlinearity-induced symmetry breaking”