Shortcut to Mode Conversion via Level Crossing in Engineered Multimode Waveguides

Chirped computer-generated planar holograms can be used to implement mode conversion in multimode waveguides based on optical analogy of adiabatic passage via level crossing. The mode converter is shortened beyond the adiabatic limit by the addition of counter-diabatic coupling. The design of mode converters using the shortcut to adiabatic passage is discussed. This design combines the compactness and robustness of the resonant and adiabatic schemes.