A Perfect Trap for Light – Allows Light To Be Absorbed Perfectly in Photosynthesis and Photovoltaics



Researchers used mirrors and lenses to create a "light trap" around a small layer in which the light beam is directed in a circle and then superimposed on itself, precisely in such a manner that the light beam blocks itself and is unable to exit the system.

A "light trap" was created that keeps a light beam from escaping. This enables optimum light absorption.

You must absorb light as completely as you can if you wish to use it effectively. Both photosynthesis and a photovoltaic system exhibit this. This is a challenge, though, if the absorption is to occur in a thin layer of material that typically allows most of the light to pass through.

The ability to entirely absorb a beam of light even in the tiniest of layers has now been discovered thanks to an unexpected technique. Utilizing mirrors and lenses, they created a "light trap" surrounding the thin layer in which the light beam is directed in a circle before being overlaid on itself. This is done in such a way that the beam of light blocks itself and is unable to exit the system. As a result, there is no other alternative for the light except to be absorbed by the thin layer.

This absorption-amplification technique was developed by research groups at The Hebrew University of Jerusalem and TU Wien, and it will be published in the scientific journal Science today, August 25, 2022. It is the outcome of the two teams' successful cooperation. Prof. Ori Katz from The Hebrew University of Jerusalem proposed the strategy, which Prof. Stefan Rotter from TU Wien helped to conceive. The lab team in Jerusalem carried out the experiment, and the Vienna team in Vienna provided the theoretical calculations.

The "light trap" set-up, which consists of a completely reflective mirror, two converging lenses, a thin, weak absorber, and a partially transparent mirror, is displayed. The majority of the light beam would typically be reflected. However, the incident light beam interferes with the light beam that is reflected back between the mirrors due to carefully calculated interference effects, which ultimately causes the reflected light beam to be entirely extinguished. The narrow and feeble absorber entirely absorbs the light's energy. Source: TU Wien

Transparent to light are thin layers.

According to Prof. Stefan Rotter of the TU Wien Institute of Theoretical Physics, "absorbing light is simple when it reaches a solid object." "Light can be easily absorbed by a thick, black wool sweater. However, you sometimes only have a thin layer of material to work with in technical applications, and you need this layer to precisely absorb the light.

There have already been initiatives to increase material absorption. The substance might be sandwiched between two mirrors, for example. Between the two mirrors, the light bounces back and forth, passing through the substance each time and increasing the likelihood that it will be absorbed. The mirrors must be imperfect for this function, with one of them having some degree of transparency; otherwise, no light can enter the space in between the two mirrors. However, this also implies that some light is lost each time it strikes this partially transparent mirror.                                                                                                                 
The light itself obstructs.

To avoid this, it is possible to apply complex methods that take advantage of light's wave qualities. Prof. Ori Katz from The Hebrew University of Jerusalem claims that "with our approach, we are able to cancel all back-reflections using wave interference." The author of this topic's thesis at the Technical University of Vienna, Helmut Hörner, explains: "In our method, too, the light strikes a partially transparent mirror first. A laser beam is divided in two by this mirror if it is merely directed at it: A smaller portion enters the mirror while the bigger portion is reflected.

After passing through the layer of absorbing material, the portion of the light beam that penetrated the mirror is transmitted back to the partially transparent mirror using lenses and another mirror. According to Yevgeny Slobodkin and Gil Weinberg, the graduate students who built the system in Jerusalem, "the crucial thing is that the length of this path and the position of the optical elements are adjusted in such a way that the returning light beam (and its numerous reflections between the mirrors) exactly cancels out the light beam reflected directly at the first mirror."

The light, so to speak, blocks itself due to the way the two partial beams overlap. A significant portion of the light would really be reflected by the partially transparent mirror on its own, but this reflection is prevented by the other portion of the beam passing through the system before returning to the partially transparent mirror.

As a result, the mirror, which was previously just partially transparent to the incident laser beam, is now entirely transparent. In essence, this turns the system into a one-way street for the light, preventing it from leaving due to the superposition of the reflected component and the portion that is guided in a circle. As a result, the laser beam is completely absorbed by a thin layer, which would have otherwise enabled the majority of the beam to pass through.

According to Stefan Rotter, "the system has to be adjusted precisely to the wavelength you wish to absorb." But aside from that, there are no restrictions. Nearly perfect absorption is always obtained, regardless of the shape of the laser beam, which can be more intense in some areas than others.

Experiments carried out at The Hebrew University in Jerusalem showed that not even air turbulence and temperature changes can affect the process. This demonstrates that it is a reliable effect that offers a variety of potential uses; for instance, the proposed mechanism may be ideally adapted to precisely collect light signals that are distorted during transmission through the Earth's atmosphere. The novel method may also be very helpful in the real world for directing light waves from weak light sources (such far-off stars) into a detector in the best possible way                                                                                                                                                                                                              By VIENNA UNIVERSITY OF TECHNOLOGY 

Comments

Post a Comment

Popular posts from this blog

Do You Sleep on Your Back or Side? Here's The Research on 'Optimal' Sleep Positions

Image
William Dement, a renowned sleep researcher at Stanford University, is quoted as saying that after 50 years of study, the only reason he can think of for why we sleep is "because we become sleepy." Sleep certainly matters for our health and wellbeing even though it may be, as one researcher put it, "the sole major habit in quest of a function." Do we, however, have it right? What do studies on sleeping positions say? Is there a proper sleeping position? The majority of people favor sleeping on their side. This is encouraging news because people who sleep on their backs are more likely to have trouble falling asleep or breathing during the night. Most of the time, we have a tendency to shift around quite a bit at night. According to a study involving 664 sleepers, on average, participants slept on their side 54% of the time, their back 37% of the time, and their front 7% of the time. Males are more likely to change positions throughout the night and move their arms, ...
Read more

The Science of Beards

Image
Here are a few facts that scientists have learned about beards as the world prepares to celebrate amazing facial hair on World Beard Day (September 3). Strong Manly Beard Men who have beards appear to be more dominant, aggressive, and strong, according to numerous studies[1][2][3] that have been conducted. In fact, men claim that growing facial hair makes them feel[4] more manly. Men who choose to grow beards tend to have higher testosterone levels than men who choose to keep their faces clean-shaven, according to research. They are also more likely to be hostile sexists, or to support the patriarchy and male dominance, as well as to believe that women belong in the kitchen, according to research on this topic. The beards (and muscles) on these males might be used to enforce gender roles. Professor R. D. Guthrie proposed in his book "Evolution of human threat display organs" from the 1970s that beards could be utilized to scare male rivals by improving aggressive and threaten...
Read more

Scientists Uncover a Surprising Connection Between Appetite and Sun Exposure

Image
Recent studies from Tel Aviv University show that women are not affected by sun exposure on their hunger levels, but males are. The study shows how the metabolic pathway is engaged differently in men and women. It was carried out utilizing lab models. Males of both animal and human species, as well as those exposed to the sun, are reportedly triggered to produce a protein called p53 that repairs any DNA damage that may have been done to the skin as a result of the exposure. The body produces the hunger-inducing hormone ghrelin in response to p53 activation. In females, the hormone estrogen stops p53 from interacting with ghrelin, preventing the desire to eat after being in the sun. The ground-breaking investigation was directed by professor Carmit Levy and Ph.D. candidate Shivang Parikh of the Department of Human Genetics and Biochemistry at TAU's Sackler Faculty of Medicine. In addition to the Tel Aviv Sourasky (Ichilov), Assuta, Meir, and Sheba Medical Centers, Drs. Yiftach Gepne...
Read more