# Shortcut to adiabaticity in full-wave optics for ultra-compact waveguide junctions

## TL;DR

This paper introduces a method to design ultra-compact waveguide junctions in full-wave optics by compensating non-adiabatic losses using a dielectric optical potential, enabling efficient mode transfer.

## Contribution

It extends the shortcut to adiabaticity concept to full-wave optics and provides a practical procedure for designing loss-compensating dielectric potentials in waveguide junctions.

## Key findings

- Numerical simulations confirm the effectiveness of the designed potentials.
- The method achieves lossless mode transfer in ultra-compact waveguide junctions.
- The approach is applicable to a broad class of two-dimensional waveguides.

## Abstract

We extend the concept of shortcut to adiabaticity to full-wave optics and provide application to the design of an ultra-compact waveguide junction. In particular, we introduce a procedure allowing one to synthesize a purely dielectric optical potential that precisely compensates for the non-adiabatic losses of the transverse-electric fundamental mode in any (sufficiently regular) two-dimensional waveguide junction. Our results are corroborated by finite-element method numerical simulations in a Poschl-Teller waveguide mode expander.