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

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.