Responsive Colloidal Crystal for Spectrometer Grating

Abstract

Diffraction gratings have a demonstrated value in optical applications, such as monochromators and spectrometers. Recent efforts have been directed at finding simple ways to manufacture diffraction gratings at low cost and under mild conditions. Here we present a practical strategy to fabricate a diffraction grating by simply treating an elastic photonic crystal film with a gradient of stress. The film was made of non-close-packed colloidal crystal arrays embedded in hydrogel polymer. Its photonic band gap (PBG) could be tuned precisely by using varying levels of pressure. Thus, when the elastic photonic crystal film was subjected to a stress gradient, a novel diffraction grating with continuously varying PBGs in the whole visible range could be achieved. The practical application of this type of diffraction grating was demonstrated in a miniaturized spectrometer system