Nonreciprocity in giant Goos-H\"anchen shift due to symmetry breaking

TL;DR

This paper demonstrates that breaking spatial symmetry in a coupled waveguide structure causes nonreciprocal giant Goos-Hänchen shifts, which can be utilized for advanced biosensing applications.

Contribution

It reveals that minimal symmetry breaking induces nonreciprocal GH shifts, providing a new mechanism for biosensing and waveguide design.

Findings

Symmetry breaking causes nonreciprocal GH shifts with opposite signs.

Adding a nanometer-thick bio-layer induces observable nonreciprocity.

Potential for enhanced biosensing based on nonreciprocal effects.

Abstract

We study giant Goos-H\"anchen (GH) shift in reflection from a near-symmetric coupled waveguide structure. We show that broken spatial symmetry can lead to GH shift with different signs for illumination from the opposite ends, a direct consequence of the nonreciprocity relations considered earlier (Opt. Lett. 27,1205 (2002)). Symmetry breaking by adding a few nm thick bio-layer to one of the guides is enough to observe the nonreciprocity. This may have far reaching implications for efficient biosensing.