When it shines

It makes 3D-Printers and laser scalples possible, and enables machines to see and cars to drive themselves—this is how photonics is shaping our future

By Michael Moorstedt (Messe München Magazine 01/2019)

On May 16, 1960, two young men in their laboratory overlooking the Pacific were bent over their latest creation. The object of their attention was a fist-sized cylinder made of aluminum, from which a few wires protruded and which contained within it a small rod of pure ruby. One of the two engineers turned the voltage up. It all happened at exactly 950 volts. The first laser beam in history shot out of the opening.

The years-long race to develop the first laser (Albert Einstein had described the basic principle as early as 1916) was thus decided. Theodore Maiman, then just 32 years old, had won the race, despite overwhelming competition and doubtful financial backers. It was a milestone in applied physics. But, the public reaction was mixed at best: The first professional journal to which he submitted his invention declined to publish it, while a local newspaper reported his invention as a “science-fiction death ray.”

In the early days, lasers hardly came into use outside of university research laboratories. The early systems had laughably small power; they were insanely complicated and their optics quickly went kaput. The laser was “a solution in search of a problem,” a resigned Maiman said at the time.

Light becomes a tool

Almost 60 years later, it is hard to imagine everyday life without his invention. Hardly any technical innovation has found so many varied applications in such a short period of time as the laser, and the end of development is nowhere in sight. Despite the early estimations of its inventor, there seems to be hardly any problem that the laser cannot contribute to solving: Laser light is used as a measuring probe, as a contactless stylus, as a friction-free cutting tool, and also, for welding metal parts or as a means of transmitting digital information.

“Almost everything that we know about the world has been learned through light,” German quantum physicist and Nobel Prize winner Theodore Hänsch once said. That sounds at first like a slight exaggeration. After all, light is one of the most natural things in the world. It enables all living organisms to see and provides everything with color. Its importance is only perceived when it is absent.

Science did not know what light actually was until well into the modern period. The explanation was first provided by quantum electrodynamics in the early 20th century: Light is neither a particle nor an electromagnetic wave, but instead consists of energy quanta—­photons. This is why the science that involves their manipulation is called photonics. The field of photonics develops devices that emit light or that capture light, whether it be a laser scalpel or a highly sensitive camera. The connection is the light, which serves as a tool. In the age of photonics, people use light to bend things into the design they want.

Cucumber Flower, © Craig P. Burrows

Light makes hidden things visible, even in everyday life. For example, with plants. What is sparkling so seductively here? The blossom of an ordinary cucumber plant, photographed under UV light.

Photo: Craig P. Burrows

Photonics is known as a key enabling technology, i.e. a technology that is of equal importance to many industries and which makes many other innovations possible—or marketable. There are many historic examples of such key technologies—and in most cases, they have led to a complete revolution in society. They changed the way people worked and lived, bringing forth previously unimaginable products. Technology historians include among them such basic technology cultures as the mastery of fire, printing, or the steam engine. In more recent history, they have included information technology and nanotechnology. Likewise, photonics. The 21st century, certain experts believe, will be based to some extent on the developments of this key technology, as was the case with electronics in the 20th century.

This prediction is borne out by hard facts from the balance sheets and quarterly reports of the photonics industry. The growth rates have been above average for years, with thoroughly positive projections for the future. Profits and employment figures appear to point in only one direction, and it is upwards. The power of innovation is enormous; the companies sometimes invest ten percent of their profits in their development departments.

There are huge future markets for the industry Jörg Mayer, CEO Spectaris

In the spring of 2019, the industry interest group photonics21.org presented a strategy paper under the headline “Europe’s Age of Light,” which predicted the path of the industry into the 2020s. Even today, European companies account for nearly 70 billion euros of the global industry turnover of 447 billion euros. Given the current annual growth rates of more than six percent, it is realistic that European companies could triple their production performance to over 200 billion euros by 2030.

“There are huge future markets for the industry,” says Jörg Mayer, CEO of Spectaris, a high-tech industry association. “To name a few, there are the topics of Industry 4.0 and smart factories, where many optical sensors, and lots of image capture and processing are required. Even the automotive industry will play a huge role in the photonics industry in terms of autonomous or partially autonomous cars.” The wide use of optical technologies means an advantage for the photonics industry, since it is so largely independent of economic cycles in other industries.

The Power of Light download as PDF

Despite all of this, optical technologies have an image problem in the general public. Most of the time, their work cannot be seen. At first, that sounds paradoxical and may go slightly beyond human imagination. Ultimately, we believe that anything bearing the name “optical” should also be visible. The classical business models of photonics, moreover, have always been played out within the B2B environment.

For the end consumer, the industry's activities have always been difficult to comprehend. But the public encounters them almost constantly in everyday life. For example, when a person wants to purchase an energy-saving light bulb at the supermarket. They go to the checkout stand, where a laser camera detects the barcode. Payment is made with a credit card, and fiber optic cables carry the relevant data at approximately two-thirds the speed of light to the servers of the respective bank.

Our fictitious customer leaves the store, whips out a smartphone, and is once again fascinated by the brilliance of the 4K AMOLED screen, on which tens of thousands of pixels are individually controlled on a tiny surface. Perhaps oblivious to their surroundings, they step out into the street, where a car stops at just the right moment because the highly developed camera of the assistance system has recognized the danger.

This banal scene, played out one way or another countless times a day, makes it clear that practically all modern conveniences are more or less based directly on the achievements and breakthroughs of the photonics industry. From smartphones to virtual-reality glasses; from smart homes to home ­robotics—photonics technologies play a trailblazing role in nearly every key electronic trend. They are also serving the consumer directly to an ever-greater degree. To learn the true potential of photonics, you must take a broad tour of the modern world (see infographic); you have to look at companies in the mobility sector, not omitting the health industry or the aeronautics and space sector, nor the manufacturing industry, nor even a detour into the agricultural industry.

Ornamental Pear, © Craig P. Burrows

In this series, the American photographer Craig Burrows explores UV-induced fluorescence. Seen here: blossoms of the Bradford pear, which smell distinctly unpleasant.

Photo: Craig P. Burrows

The players in the industry are just as diverse as the fields of application. They are all there, from the typical German SMEs, which dominate the world market as hidden champions in their niche, to the global mega conglomerate with billions in revenue. The Swabian Trumpf Group belongs to the first category. For a long time, the company was a very profitable but conventional manufacturer of machine tools, mostly for sheet metal working.

In the 1980s, Trumpf introduced the first self-developed laser—it was the starting point of an unheard-of success story. Today, the company is among the market and technology leaders in the field of lasers. In brief, they build the devices without which other devices could not be manufactured. The highlight of Trumpf’s product portfolio at first glance seems rather unremarkable. The Truprint 5000 is a big gray box with two small windows, which allow a view into the interior, and a large monitor that serves to control it. To the photonics expert, what takes place inside is the logical application of their craft, but to the layperson, it seems like magic. Three laser beams dance over a dark gray surface. Sparks flash. As if from nothing an object emerges.

The concentrated light melts metal, layer by layer, into nearly any three-dimensional object; it forms steel as well as aluminum, titanium, and various alloys. The metals are present in highly pure powder form. A strong laser melts the powder exactly on the spot specified in the CAD data, and binds it

to the layer below. In this way, the component is built up additively, layer by layer, with the individual layers sometimes being no thicker than a few micrometers. The excess powder can simply be sucked away later and recycled.

Production is going to be more efficient, flexible and precise.

This process is called selective laser melting, but is also often referred to as metallic 3-D printing. Trumpf has been involved in research on this technology since 1999, together with the Fraunhofer Institute for Laser Technology in Aachen (see interview, page 16). There are many advantages in comparison to conventional methods such as casting or milling: There is no metal abrasion in the layer construction process, and only the metal that is needed for the component is used. In addition, no molds need to be prepared in advance. Production is therefore more efficient and flexible. Additive manufacturing is overtaking one industry after another: It allows individual dental crowns to be created, forms orthopedic implants, and creates industrial tools, and complex, lightweight automobile parts. With the help of a new green laser, precious metals such as gold or copper can be worked on, allowing for jewelry pieces to be printed.

Although laser melting was until recently used primarily for the production of prototypes, today the process can be used for mass production. “3-D printers are becoming established in industry to the same extent that paper printers are used in private households today,” says Frank Peter Wüst, Director of Materials, Applications, and Consulting at Trumpf.

By 2030, the company intends to generate revenues of half a billion euros in this segment. Additive production processes allow for more complex and lighter structures, which nevertheless are enormously stable while being particularly suited to use in air transport, for example in the manufacture of engine blades. According to one study from the market research firm Technavio, the use of additive production processes will grow by more than a quarter annually in the coming years. “Photonics is disruptive,” says Peter Leibinger, CTO of Trumpf, summing it all up.

3-D printers are becoming established in industry to the same extent that paper printers are used in private households today. Frank Peter Wüst, Director of Materials, Applications, and Consulting at Trumpf

The disruptive power of photonics can also be seen in other industries. For example, a modern car would hardly be imaginable without photonic innovation—and it is putting manufacturers and their business models under pressure. Steerable laser headlights reaching several hundred meters, which adjust to the direction of the road and which automatically dim for oncoming traffic, or lasers that project route and traffic information onto the windshield, are the easy part.

In order to realize its vision of autonomous driving, the automobile industry needs technologies that can very quickly gather information about the environment over long distances and under adverse external conditions. Besides high-performance stereo cameras that give the automobile, so to speak, spatial vision, lidar (light direction and ranging) is one of the most important sensory tools of a self-driving car of the future. Similar to radar, the lidar system emits laser impulses and, based on the spectral color of the light reflected from the surroundings, measures the speed and distance of the other traffic. The laser scanner provides an accurate image of the surroundings in detail up to 25 times per second. This information is then transformed by the onboard computer into the appropriate control commands.

Up till now, lidar systems have operated using a rotating mirror, which steers the laser beams and thus illuminates the field of view. That made them not only relatively expensive, but also susceptible to interference. Newer versions rely on liquid crystal metasurfaces and operate without mechanically moving parts. In this way, the system is intended to operate more reliably and have a longer lifespan compared to the competition. “Due to the fact that it involves only one chip, the system is also much more cost efficient,” explains Luc Van den Hove, President and CEO of the Imec research institute, where a similar technology is under development. “This is critical prerequisite for putting lidar in all automobiles.”

Amaryllis, © Craig P. Burrows

The amaryllis is also great to look at in the visible spectrum—which makes it a favorite ornamental flower. You normally see its flower petals shimmering red.

Photo: Craig P. Burrows

However, it is not only inanimate materials that can be manipulated with lasers. In the field known as biophotonics, optical technologies are being employed in both the diagnosis and treatment of illnesses. Even the inventor of lasers mentioned in the introduction, Theodore Maiman, suspected that the technology could one day be useful in medicine. He himself experimented on rats. One could possibly even concentrate the laser light “on a single blood cell.” But, until that comes about, there is “still a way to go,” according to Maiman at the time.

However, things moved faster than expected. Just ten years later, experimental physicist ­Arthur Ashkin was working on the optical tweezer. Viruses, bacteria, and other living cells can be held in place or moved by laser light, without being destroyed. In the 1980s, Donna Strickland and Gérard Mourou developed the chirped pulse amplification technique, in which ultra-short laser pulses are produced with simultaneously extremely high power. Millions of shortsighted people profit from this breakthrough in the form of the LASIK method, in which irregularities in the cornea of the eye are removed using a laser scalpel. Last year, the three laser researchers received the Nobel Prize in Physics for their work.

Regardless of whether in medical practice or in the factory, the computer systems that keep the modern world running need the most accurate information possible about this world. Photonic systems provide the necessary eyes and sensory organs. Their sensors form the fundamental basis of all applications.

Stemmer Imaging is one of the market leaders in the area. The image-processing specialist from the Munich area had a successful initial public offering just this past year. Peter Keppler is the Director of Global Sales. He says: “In my view, those involved in automation must deal more and more with the topic of image processing, since without this technology, in many cases they will no longer be able to meet the requirements of Industry 4.0 in the future.”

Persian Silk Tree, © Craig P. Burrows

Burrows illuminates his images for up to 20 seconds— and holds his breath. The tiniest breath of air would blur the image.

Photo: Craig P. Burrows

In the smart factories of the future, hundreds or thousands of component parts must be inspected for deviations in the micrometer range; conveyor belts move at 30 meters per second or more—the naked human eye is simply no longer the measure of things here. However, the cameras used in industrial image processing have very little to do with the devices the end consumer uses to film their vacation highlights.

Approaches such as hyperspectral imaging allow the chemical composition of a material to be determined via analysis of its light absorption—entirely without destroying the sample in the process. In this way, products such as easily damaged foods can already be analyzed in their packaging. Other industries are also benefitting from contactless testing. For example, the pharmaceutical industry. Instead of simply taking random samples for quality assurance, a 100 percent inspection in ongoing operations can be guaranteed. It is not just the hardware that is critical to the exact measurement and analysis, but also the corresponding software. Ultimately, the images must not only be taken, but also processed. The progress achieved in recent years in the area of machine learning and artificial intelligence has led to the situation in which even the smallest quality deviations can be counteracted, such that no production errors whatsoever arise. According to Peter Keppler, “thanks to the excitement that has sprung up around the concept of deep learning in recent years, the use of this technology for image processing has now become popular on a broader basis.”

The modernization of illumination is a decisive key for the reduction of worldwide energy usage. Karsten Vierke, CEO DACH Signify

The mechanisms of photonics thus permeate the entire industrial value chain. The obvious aspect of optical technology is, at least at first glance, also the most spectacular. Huge displays with stable viewing angles illuminate the inner cities of the world, while light artists use laser beams to create holographic dream landscapes of shining particles in the air. Mini-drones equipped with LEDs are turned into electric glowworms and, in factories converted into urban farms, special UV diodes make vegetables sprout like the proverbial bad weed. Using targeted illumination, the operators can even control the flavor and nutrient content of the plants.

And, of course, there is still the essential property of light: It is bright. Light emitting diodes have also left a dramatic transformation in their wake in terms of efficiency and performance. Just a few years ago, we weren’t even sure whether a light emitting diode could ever achieve the brightness of a light bulb. Today, nearly 20 percent of worldwide power consumption is attributable to illumination systems of all types. LEDs and other efficient and contemporary lighting technologies thus carry enormous potential: According to a study by the US Energy Department, the global conversion to LED illumination would save 800 million tons of CO2. That corresponds to the output of nearly 700 coal-fired power plants, which could be saved. Per year. “The modernization of illumination is a decisive key for the reduction of worldwide energy usage,” says Karsten Vierke, CEO DACH (Germany, Austria, and Switzerland) of lighting manufacturer Signify.

For anyone involved in photonics, the future is always happening in the present a little bit. Just as one can expect from a key technology photonics is currently providing a new upswing in the weakening semiconductor industry. One example is EUV lithography, in which the semiconductor is exposed to extreme ultraviolet rays, which enables smaller and more efficient circuits.

An Industry with unimaginable possibilities

Computer chips are thus made more powerful. Lasers operate with a very short wavelength of 13.5 nanometers and so can print ultra complex structures on the silicon wafer. The first chips using this technology will be delivered later this year. They ensure that the famed Moore’s Law will continue to apply for a few more years. Should the era of silicon-based computers nevertheless come to an end, it will probably be lasers that manipulate the individual atoms in quantum computers.

How will photonics develop? “That’s like asking in the 18th century how electricity would develop. No one could have answered that,” says Reinhart Poprawe, Director of the Fraunhofer ILT. What is certain is that the industry still holds unimaginable possibilities. Even Albert Einstein knew that not all of light’s secrets had been uncovered. “As he once wrote: “All the 50 years of conscious brooding have brought me no closer to answering the question, ‘What are light quanta?’ Of course today every rascal thinks he knows the answer, but he is deluding himself...”