“Colorful Black” – What Designers Can’t Do With Scientists

I want colorful black. This demand from The Father of Party A is a stalker in the design circle of the last two years. Previously, designers of the US cycling brand SPECIALIZED (Lightning) used rainbow elements representing the world champion on their black bodies when designing their own bikes for the world champion.

In the sun, the body black spray paint under the sequins reflected by the sun, but also to achieve the so-called “colorful black” effect.

However, a team from the School of Physics and Astronomy of the University of Birmingham, the Department of Physics of the University of Munich, the Department of Physics at Imperial College London, the School of Modern Engineering and Applied Sciences of Nanjing University, the National Key Laboratory for Solid Microstructure Physics, the Centre for Collaborative Innovation in Microstructure Science and Technology, and the School of Electronic Optical Engineering, University of Posts and Telecommunications, The team at the Institute of Microelectronics recently designed an optical system consisting of disorderly plasma nanoclusters that can extract a variety of colors from black, which can really be colorful.

On 24 March 2020, local time, the team was entitled Manipulating Disordered plasmonic systems by external cavity with with broadband broadband from Absorption to reconfigurable reflection, from broadband absorption to reconfigurable reflection of the outer cavity to manipulate disordered plasma systems, is published online in Nature Communications.

Disordered biological structure swayed by nature

The research was inspired by the disordered biological structures that are prevalent in nature, with broadband light response and robust disturbances.

The nanoscale structure of the surface of an object reflects light, producing a variety of colors.

However, if the surface of an object is in a state of disorder on a nanoscale structure, the light is either fully absorbed or fully reflected, which is either black or white.

In nature, a beetle called a platinum turtle has white scales, and British physicists have been inspired by the platinum turtle to develop a new type of ultra-white paper. Using a similar approach may also lead to ultra-thin paint siphons as white as paper, or to improve the color of writing paper, human teeth, and even to the brightness of luminescence and displays.

In addition, the black-and-white striped squid on the surface, the black feathered polar bird, these make the world more diverse, wonderful phenomenon, in fact, are the influence of disordered structure.

In fact, with the development of nanophotonics and nano-manufacturing technology, disordered nanostructures are used in different optical systems for photopositioning, photon transmission and energy harvesting because of their unique characteristics – unconventional intensity statistics, broadband transmission enhancement, ideal focus, broadband light trap and broadband energy harvesting. However, the adjustability of disordered systems with broadband light response is rarely studied.

Disordered optical system consisting of plasma nanoclusters

Based on this, the research team realized the control of the disordered plasma system, and the transition from broadband absorption to tunable reflection through the deterministic control of external cavity coupling.

The following image shows a 3D full-wave simulation of a disordered plasma system.

Specifically, the team designed an optical system consisting of disordered plasma nanoclusters, either as broadband absorbers, or with reconfigurable reflectors in the visible light region, based on a broad model.

As shown in the figure below, the nanoclusters are mainly arranged out of order by silver (Ag) nanoparticles of varying sizes, located on a dielectric material made of lithium fluoride (LiF), with a layer of silver mirror (Ag mirror) under the lithium fluoride.

There is one of the most important parts of this structure, the transparent cavity known as LiF spacer. The transparent cavity formed by the gap between lithium fluoride does not dissipate light, in which photons resonate at different frequencies and release various colors depending on different wavelengths.

The researchers set the cavity’s thickness to increase linearly along the diagonal, allowing the system’s light response to be absorbed from more than 90% of the visible light broadband to different reflections depending on the wavelength (reflected wavelengths between 400nm and 750nm).

In layman’s terms, the researchers changed the light response pattern by changing the cavity thickness, and then realized the “colorful black” as the article began.

The following image shows an image of the nanocluster structure, which, after a black transition, begins with a variety of colors from black along the diagonal.

Align white stone paintings for color reproduction

So, is this kind of system that listens to a very mysterious, practical?

In fact, to test the viability of the system, the team printed Qi Baishi’s watercolor Peony (digital replica to the left below), which showed that the work contained several common colors, such as red, pink, yellow, green and black. The researchers say that simply adjusting the thickness of the transparent cavity can reproduce the original with extremely high color accuracy (right below).

It can be seen that the significance of this achievement is not only reflected in the further understanding of the physical sense of disorder, but also for a variety of practical applications (e.g. structural color patterning) provides new ideas, as the research team said:

In physics, we are used to thinking that disorder in nanoprocessing is bad, but here we have shown that in certain scenarios, disordered structures can be superior to ordered structures. The disorderly systems we design can also be used in other physical fields, such as new sensing technologies.