Multicolor Changeable Optical Coating by Adopting Multiple Layers of Ultrathin Phase Change Material Film

Abstract

The multilayered optical coating whose structure consists of optical cavity and multiple layers of ultrathin phase change material (PCM) film is presented. The color changing is enabled via transition between amorphous and crystalline phases of PCM, which is accompanied by high optical contrast. The phase transition of each PCM layer, separated by ultrathin oxide barrier, can be realized through various crystallization temperatures with respect to the different thickness of ultrathin (<10 nm) PCM film. Accordingly, notable multicolor changing was achieved by thermally or electrically induced selective phase transition of double PCM layers, and its results were compared with transfer-matrix optical modeling. Further evaluation of optical simulations also demonstrated the possibility of increase in expressible colors with increasing number of layers.

Non-binary Colour Modulation for Display Device Based on Phase Change Materials

“…Only two colours can be tuned via the full crystallization of the few-nanometres-thick GST layer without the contribution provided by changing the thickness of indium tin oxide (ITO) beneath the GST. Previous studies tend to use single phase change material (PCM) as a highly absorbing dielectric layer to realize colour depth modulation, for example, Ag 3 In 4 Sb 76 Te 17 (AIST)9 and two ultrathin GST films10. However, the method based on two ultrathin GST films needs a barrier layer to avoid interdiffusion, which will adversely interfere with the amorphization during actual device operation10 and is unstable because it need accurate thickness control.…”

Switching of the direction of reflectionless light propagation at exceptional points in non-PT-symmetric structures using phase-change materials

“…Such a thermal barrier layer keeps surrounding materials isolated from heating and protects them from harmful interaction with the GST film, when GST is switched between its two phases by optically, electrically or thermally provided heat stimuli [35,40,45]. For example, Ta 2 O 5 , Al 2 O 3 and Si 3 N 4 are materials which can be chosen for the thermal barrier due to their low thermal conductivities [35,40,45]. We found that the addition of such a thin thermal barrier layer does not affect the functionality of the proposed structure.…”

“…2(d) and 2(f)]. Note that the bulk refractive index of GST that we used here is still valid for the ultrathin GST layer with 2 nm thickness [40,45].…”

“…GST has been widely studied for applications in non-volatile, rewritable optical data storage and memory [38,39]. Recently, a variety of optically reconfigurable GST-based active photonic devices have also been demonstrated [40][41][42][43][44][45].…”

Superresolution 4π Raman microscopy

“…Through the study of a nanolayer stack, we show that using a 4π configuration [9] to Raman microscopy has a great potential to help in this quest. Nanolayers have attracted increasing interest across a wide diversity of fields, such as optics [10], energy storage [11], biology [12], and pharmacology [13]. They are typically characterized via ellipsometry, electron microscopy, or x-rays; however, these techniques share a common limitation: data from complex stacks of nanolayers become increasingly difficult to interpret.…”