Controlled angular redirection of light via nanoimprinted disordered gratings

Abstract

Enhanced control of diffraction through transparent substrates is achieved via disordered gratings in a silica sol-gel film. Tailoring the degree of disorder allows tuning of the diffractive behavior from discrete orders into broad distributions over large angular range. Gratings of optical quality are formed by silica sol-gel nanoimprint lithography and an optical setup for the measurement of continuous diffraction patterns is presented. Sound agreement is found between measurements and simulation, validating both the approach for redirection of light and the fabrication process. The disordered gratings are presented in the context of improved interior daylighting and may furthermore be suited to a wide variety of applications where controlled angular redirection of light is desired.

Nanoimprint lithography: 2D or not 2D? A review

“…The characteristic sizes are as follows: area 16 9 16 mm 2 for a single LED-based waveguide, EBL exposure field 320 9 320 lm 2 , 4.5 lm sub-field stitching and 20 nm step size. The simulation of optical texture was based on 74,000 grating units, and the optical design (i.e., orientation and density variation) was optimized for uniform illumination (collimation) in the active area, similar to [158,159]. The slopes in the prepatterned 2-lm-thick resist were designed to exhibit a blazed angle a with approx.…”

Optical role of randomness for structured surfaces

“…• Secondly, phase gratings using the properties of randomness for concrete products like e.g. a surface giving controlled angular redirection of light for windows to improve indoor lighting environment has been presented in [11]. Here the effect of in-plane randomness is observed, but no mathematical explanation is given.…”

“…Since the array factor is now scaled by the number of units, we will refer to it as the Scaled Array Factor (SAF). The expression in (11) will be the foundation for all following analyses, as it shows how a prediction of the reflection from the unit structure (this we denote unit response) and a knowledge of the position of its copies (the ∆r n 's) can give a complete description of the reflected radiance. Furthermore it decouples the positioning of the structures from the response of the structure, which means that when designing e.g.…”