First experimental observation of array of photonic jets from saw-tooth phase diffraction grating

Modern materials science and technologies based on the advanced lithographies, nanophotonics and electronics use the effect of super-focusing of light based on photonic nanojet (PNJ) array produced by close packing of spherical microparticles. To control the key parameters of photonic jets array the phase grating may be applied. For the first time the experimental direct imaging of the spatial and amplitude features of PNJ ensemble formation near the shadow surface of a saw-tooth phase diffraction grating is presented here for 3 different wavelengths: 405, 532, and 761 nm. It is shown that the PNJs array from such phase diffraction gratings, in contrast to microparticle self-assemblies, produces an array of PNJs with controlled characteristics: the length, width, and focal length of PNJ. They are changed in proportion to the incident wavelength. For the designed wavelength of λ₀ = 532 nm, the length of PNJ is 5.48 λ ₀, the beamwaist is 0.75 λ ₀ and the focal length is equal to 1.1 λ ₀.