Gradient-index materials based on thiol-ene networks

Gradient-index (GRIN) optics offer spatially varied refractive indexes that can enhance current imaging technologies. Current methods to fabricate GRIN optics are highly complex and costly. Here we report a simple and efficient method that utilizes commercially available reagents to fabricate polymeric GRIN optics with significant refractive index differences (Δn = 0.04). First, two different mixtures of network precursors are layered and time allotted for molecular diffusion in the liquid state, prior to curing. The resulting, partially mixed layers are UV-cured to yield clear, glassy molecular networks with fixed refractive index gradients. The fully cured network resins exhibit smoothly varying composition and refractive index over centimeter length scales, confirmed by spectroscopy and interferometry.