Liquid immersion enables 3D printable diffractive optical elements

Diffractive optical elements, used to shape the wavefront of incident light, are ubiquitous in optics thanks to the high flexibility in design and compactness that they offer [1]. However, the nanoscale-precision requirements typically necessitates a complicated fabrication process, e.g. nanolithography. Here we present the liquid immersed DOE. By immersing the DOE in liquid, i.e. decreasing the difference between the refractive indices of the DOE and the surrounding media, we can scale up the dimensions of the DOE from the nano-scale to the micro-scale (Fig. 1 a&b), since the accumulated phase per DOE pixel can be described by:\begin{equation*}\Delta \phi = \frac{{2\pi h}}{\lambda }\left( {{n_{DOE}} - {n_{media}}} \right),\tag{1}\end{equation*}where Δϕ is the accumulated phase difference between light traversing the DOE compared to the surrounding media; λ is the wavelength; h is the height of the DOE; and n refers to the refractive index of the DOE material and surrounding media, respectively.