Angle-dependent structural colors in a nanoscale-grating photonic crystal fabricated by reverse nanoimprint technology.

Xu Zheng,Qing Wang,Jinjin Luan,Yao Li,Ning Wang,Rui Zhang

doi:10.3762/bjnano.10.120

Abstract

The structural color of angle-sensitive photonic crystals has attracted great interest because of a possible application in visual sensors. The appearance of a photonic crystal is mainly influenced by the optical properties, structural parameters and the observation angle. In this work, an angle-sensitive photonic crystal with nanoscale gratings was fabricated through reverse nanoimprint lithography. The periodicity and the structural color were investigated through measuring reflection spectra. The structural color of the photonic crystal has a period of 90°. Distinctive colors spanning the entire visible spectrum can be seen when the crystal is rotated. In addition, there is a blue-shift of the peak wavelength when the observation angle is increased. An equation for the observed wavelength as a function of the observation angle is proposed.

Highlights

Photonic crystals have been extensively investigated in recent years because of their potential application in visual sensors [1]
The results show that the mould patterns were perfectly transferred to the film surface through reverse nanoimprint lithography (NIL)
An angle-sensitive photonic crystal with grating pattern was fabricated through reverse NIL to investigate the effects of horizontal and vertical observation angles on its structural color

Summary

Introduction

Photonic crystals have been extensively investigated in recent years because of their potential application in visual sensors [1]. Much attention has been paid to photonic crystals the reflection wavelength of which changes with the observation angle [2]. As period and depth of the optical structure of the photonic crystal are fixed, the structural color depends on the observation angle [3,4]. Studies show that photonic crystals with grating pattern are the favorable candidates for a variety of applications, due to their compact structures, simple fabrication process and excellent spectral characteristics, and because reflection wavelength and observation angle are closely connected [5,6,7]. Nanoimprint lithography (NIL) and self-assembly are the two main methods to prepare photonic crystals with grating pattern [8,9,10,11]. NIL is most often reported because it is inexpensive and applied [12,13,14,15]

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Results

Conclusion