Translate optical Tellegen coupling into waveguide isolators

Translate the optical Tellegen response demonstrated in resonant metasurfaces into integrated waveguide geometries suitable for nonreciprocal optical isolation.

Background

The review identifies magnetoelectric, or Tellegen, coupling as a distinct constitutive channel for nonreciprocal response. In a Tellegen medium, the relevant magnetoelectric tensors satisfy a nonreciprocal relation, and recent metamaterial and metasurface demonstrations have achieved substantially enhanced effective Tellegen parameters.

Although an optical Tellegen effect has been demonstrated in a resonant metasurface at 830 nm, the review states that implementation in waveguide geometries remains unresolved. Such a translation would be needed to assess whether the effect can support practical integrated isolators and electrically tunable nonreciprocity.

References

The optical Tellegen effect has been recently demonstrated in a resonant metasurface at $830$~nm, reaching an effective parameter two order of magnitudes higher thant any natural material from spontaneous magnetization alone, although translation into waveguide geometries remains open.

— On-chip optical isolators  (2610.17862 - Mikhail et al., 13 Oct 2026) in Section 11, “Conclusion and outlook”

Finally, self-induced nonreciprocity, in which circularly polarized light generates a local spin polarization that acts as a time-reversal-odd bias, has enabled isolation exceeding 60~dB in atomic vapour, including in the presence of simultaneous counterpropagating excitation. Translating this mechanism to an integrated platform remains an open challenge.

— On-chip optical isolators  (2610.17862 - Mikhail et al., 13 Oct 2026) in Section 11, “Conclusion and outlook”