Monolithic polymer microlens arrays with antireflective nanostructures

This work reports a novel method for fabricating monolithic polymer microlens arrays with antireflective nanostructures (AR-MLAs) at wafer level. The antireflective nanostructures (ARS) were fabricated by etching the curved surface of polymer microlens with a metal annealed nanoisland mask. The effective refractive index of ARS was controlled with the etch profile of nanostructures to reduce the mismatch in refractive indices at air-lens interface. The reflectance of AR-MLAs decreases below 4% from 490 nm to 630 nm in wavelength. The lens transmission significantly increases by 67% across the visible spectrum by minimizing the reflection and absorption, compared to that of MLAs without ARS.