Fig. 6: Measurements in 3D printed dielectric waveguides for out-of-plane defect modulation. Shown are the intensities in the waveguides at the output facet.

a Measurements for several structures with different periods (frequencies of modulation ω) with otherwise the same parameters at fixed wavelength. For small frequencies, the light is localised around the defect (at x = 0). When the frequency is increased, light couples to the bulk states (0.56 ≤ ω/J₁ ≤ 1.12) and localises in the defect again for large frequencies. b In a structure with fixed period of the defect modulation, the wavelength is tuned. Light is delocalised, i.e., couples strongly to the bulk, when the first Floquet mode hits the bulk band, starting at λ = 750 nm. Note that J₂/J₁ changes with the wavelength: J₂/J₁= 0.47 (680 nm), 0.48 (710 nm), 0.52 (750 nm), 0.53 (780 nm) and 0.55 (810 nm)