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A LEAP FORWARD IN THE APPLICATION OF ULTRAFAST LASERS

DR XIAOMING YU IS BASED WITHIN CREOL, THE COLLEGE OF

OPTICS AND PHOTONICS AT THE UNIVERSITY OF CENTRAL FLORIDA IN THE US. HE IS WORKING ON A NOVEL NANOMANUFACTURING PROCESS THAT WILL LEAD TO THE CREATION OF NEW AND IMPROVED MEDICAL DEVICES WITH A RANGE OF BENEFITS

On 22 March 1960, American Now that we are firmly within the 21st century, research comes in. They can do this because, Charles H. Townes and Arthur L. Schawlow technological advancements are enabling unlike other types of laser, ultrafast lasers were granted a patent for something called more developed lasers to be used in a range of (also known as ultrashort-pulsed lasers) emit an optical maser. While this term might be applications, with enormous benefits across a bursts of that are unbelievably short. So unfamiliar to some of our readers, the majority range of fields. Dr Xiaoming Yu, who is based short in fact that the light they emit travels a will have heard of what it has become known within CREOL, The College of and shorter distance than a fraction of the width of as in the years after: lasers. Lasers are used in Photonics at the University of Central Florida a human hair! a wide range of different applications, from in the US, is working on using ultrafast lasers CD players, to medical applications and even as a potential manufacturing tool – one that These ultrashort pulses are 100 trillion self-driving cars! could lead to the development of new and brighter than sunlight. “When shining onto a improved medical devices (as well as many material, these bursts create extremely high However, the invention of lasers would not other possible applications). and pressure that can only be have been possible were it not for ’s found at an explosion of thousands of tons discovery of elementary quanta (for WHAT ARE THE BENEFITS OF USING of TNT or a small nuclear bomb, turning the which he received the 1918 in ULTRAFAST LASERS? material to a plasma (the fourth state of ). Later, Einstein suggested that it Firstly, lasers have the ability to modify matter),” explains Xiaoming. “What is more might be possible to stimulate materials from the inside! For instance, there important is that these bursts are so short that and make them emit light of a particular are bubblegrams, which are solid blocks of the high does not have enough wavelength. As usual, Einstein was way ahead glass that have been exposed to laser beams to to spread, so the plasma only affects a of his time and it was more than four decades produce 3D designs inside. The precision that small area. This is called ‘nonthermal ablation’ after this that his theory was demonstrated enables these artworks to be created also has and is unique to ultrafast lasers and the reason in practice. So, what is a laser? Well, put exciting applications in 3D printing to produce that small features can be made.” simply, a laser is something that can make medical devices and even artificial tissues. billions of generate trillions of light HOW HAVE XIAOMING AND HIS particles (protons) that line up to produce a The second benefit is the high resolution TEAM WORKED TO DEVELOP concentrated beam of light. So concentrated that ultrafast lasers boast, which means they THESE LASERS? is this beam of light, that it makes lasers have extremely small features – smaller than Xiaoming has developed a new process to extremely precise and powerful. a red blood cell – which is where Xiaoming’s fabricate large-area nanostructures on DR XIAOMING YU Assistant Professor of Optics & Photonics, CREOL The College of Optics and Photonics University of Central Florida, USA

FIELD OF RESEARCH Optics and Photonics

RESEARCH PROJECT

Developing a new nanomanufacturing process that can be used in the fabrication of medical devices and display panels. The findings will improve various aspects of our lives.

FUNDER

National Foundation dielectric materials, that is, materials that do To overcome this, Xiaoming and the team not conduct electricity. The new process is designed their instrument in such a way that from other researchers and acts as the basis called Laser Etching by Avalanche-assisted potential disturbances could be minimised of other findings on the ultimate resolution Photoabsorption (LEAP), which uses the and compensated for. “The entire instrument limit of ultrafast lasers. Over the course of ultrashort laser pulses mentioned earlier. was built on a single piece of metal so each their studies, they came across an unexpected “LEAP uses multiphoton absorption and component would move in the same way if result when two laser pulses were slightly another photo-physical process called there was any vibration. We mounted the misaligned, and the overlapped region created avalanche ionisation, which means an ultrafast mirrors on motors so the timing of the pulses a feature that was smaller than that from each laser beam creates a cascade of energised could be tuned precisely,” explains Xiaoming. individual pulse. Discovered purely by chance, electrons similar to an avalanche – one “Since the pulses were so strong, we looked at this helped demonstrate a way of enhancing turns into two, then four, then eight, and blocked every possible way the beam could the resolution. etc. This process repeats itself as long as there escape and cause damage.” are new pulses coming in,” says Xiaoming. The next steps are to use the instrument to “In LEAP, such a process is controlled so Of course, alongside these experimental produce pulses with characteristics in favour precisely that the last pulse creates just enough challenges there is the overall challenge of the aforementioned avalanche process. energised electrons to form a nano-plasma, regarding the big question the team want to “We will make the laser beam go into a small which is smaller than using multiphoton answer: how to make ultrafast lasers a more focus and use it to fabricate nanostructures on absorption only, so the resolution is enhanced.” versatile and useful manufacturing tool. the surface and in the bulk of glass samples,” Xiaoming is therefore spending time working to says Xiaoming. “Ultimately, my work can be HAVE THERE BEEN ANY CHALLENGES improve the concentration of the laser energy used in the fabrication of medical devices, IN THE RESEARCH? and deposit energy more efficiently. such as stents and scaffolds, laser surgery and Yes! When working with these ultrashort the processing of display panels. In addition, pulses, it becomes extremely challenging to WHAT ARE THE NEXT STEPS FOR smartphone panels are processed by lasers and control them. Given that the pulse travels THE RESEARCH? my work will make the manufacturing of these such an incredibly short distance, the slightest Xiaoming and the team have focused on materials more precise and error-free.” thing – like a slight misalignment of the building the instrument for the experiment to beam or even movement in the air – can prove that it can work. This has enabled them change the characteristics of the pulse. to develop a model that unifies the results ABOUT OPTICS AND PHOTONICS

The word photonics comes from the Greek “I am collaborating with a US manufacturer Even though this has been studied word ‘phos’ meaning light (and is also the of fabric-processing machines which will be for more than half a century and a lot has reason we call particles of light ). The using ultrafast lasers as the main processing been learned about the interaction between invention of the laser in 1960 gave rise to the tool. I hope the LEAP method, once fully ultrashort laser pulses and solid materials, field of photonics, which is closely related developed in the current project, will help Xiaoming is confident that this complex and to optics. However, optics was established laser processing companies reduce cost and fascinating topic has only had its surface far before photonics, with the development increase throughput.” scratched. “On the theory side, many models of lenses for microscopes, the refracting dealing with steady-state phenomena would lens and the reflecting mirror. Of course, WHAT TYPES OF COLLABORATION HIS not work under the extreme temperature and with the advent of significant technological XIAOMING ENGAGED IN? pressure environment induced by the ultrafast developments, researchers have been able to Since lasers were invented more than 60 years laser, so new theories need to be developed. advance the field of photonics in considerable ago, the field has been interdisciplinary by Practically, ultrafast lasers are still difficult ways, particularly those related to fields like nature and that continues to the present day. to use because of the stringent requirement quantum optics and quantum electronics. Xiaoming is currently working with a chemist on the environment,” says Xiaoming. “We to develop a new material suitable for 3D need engineers to make ultrafast lasers WHAT DOES XIAOMING FIND MOST printing and a mechanical engineer to develop ‘smarter’, so that they can sense any change REWARDING ABOUT HIS RESEARCH? a multi-physics model that will help scientists in the environment and make adjustment by Xiaoming is a pioneer in the fields of optics and understand different types of laser-induced themselves. The , Richard Feynman, photonics; he has developed many techniques phenomena. And then, of course, there is once imagined a future when atoms can be that have since been used by other researchers the team he collaborates with at his college manipulated individually to build things like to solve real-world problems. “A technique I at CREOL. nano-robots. We are far from this, but we developed when I was a graduate student – are moving toward this goal with the new ‘polarisation-sensitive chemical etching’ – has WHAT WILL THE NEXT GENERATION generation of scientists and engineers.” been used to fabricate microfluidic chips used OF SCIENTISTS ENGAGED IN OPTICS in large chemical plants,” explains Xiaoming. AND PHOTONICS BE FOCUSING ON?

PATHWAY FROM SCHOOL TO OPTICS HOW TO GET AND PHOTONICS INVOLVED Optics is a sub-field of physics, so basic physics courses are helpful, as well as courses IN OPTICS that you will likely encounter in high school. “It is worth taking more advanced courses in subjects AND PHOTONICS such as static and dynamic electromagnetics, solid state physics, linear , matrices, linear systems, quantum and thermodynamics,” explains Xiaoming. “I also recommend taking as many chemistry and biology modules as possible because optics and photonics is a highly •  Optics.org is dedicated to providing interdisciplinary field.” daily coverage of the optics and photonics industry and the markets You will need a degree in a relevant subject for postgraduate study. that it serves: https://optics.org/ https://www.careerexplorer.com/careers/photonics-engineer/ •  Photonics.com has a heady list of societies and associations to explore: https://www.photonics.com/EDU/ EducationalInstitutions.aspx?TID=1 XIAOMING’S TOP TIPS •  The average salary for a photonics engineer in the US is approximately 01 $99,000, although that figure  Have confidence in everything that you do. Always keep in mind that every piece of can rise significantly for more technology you are using in the present moment was invented by people just like you. experienced engineers. 02  Keep an open mind and consider every opinion, particularly criticisms, which are often the best advice you can have to improve yourself.

03 Never be afraid of making mistakes – the important thing is to learn from your mistakes. Do not let the fear of failure stop you from dreaming big but remember to always examine your ideas carefully. HOW DID XIAOMING BECOME AN EXPERT IN OPTICS AND PHOTONICS?

WHAT WERE YOUR INTERESTS AS A fascinated by science after learning about this there are problems that exceed my ability. CHILD? in high school. Instead of trying to force myself to work on I liked astronomy when I was young, which the problem, I seek help from others – and was an interest that was partly influenced by WHAT ATTRIBUTES HAVE MADE YOU not always those who have the exact expertise, Stephen Hawking’s book ‘A Brief History SUCCESSFUL AS A SCIENTIST? but anybody who has an open mind and is of Time’ and partly because a night sky I wouldn’t call myself successful! There are so willing to share their opinions from a different always triggered my imagination about the many things to learn which, I guess, counts perspective. I find this often broadens my many unknown worlds beyond our reach. I as an attribute – the acknowledgement views and helps me solve problems using a liked reading magazines about science and that there is always something new to learn. new approach. technology and enjoyed tinkering with (often Another key attribute is critical thinking, destroying) things that had moving parts in which is the ability to provide independent WHAT AMBITIONS HAVE YOU SET them. I guess it was because I wanted to know assessment of facts and opinions. The YOURSELF FOR THE FUTURE? how stuff worked – that’s how I explained third attribute is persistence. There will be I would like to see laser materials processing, it anyway! challenges in research and many of them have in general, and ultrafast laser processing, not been solved or even encountered before. in particular, become more widely used WHO INSPIRED YOU TO BECOME A It is in such moments that scientists and manufacturing tools. Lasers are versatile in SCIENTIST? researchers need to hold on to their beliefs that they can be tailored to suit different types Famous scientists like Stephen Hawking and try everything they can. Every problem of applications, like a swiss army knife. I would and Richard Feynman, mainly through their has a solution. like to continue my contribution in this field books. I was inspired by my high school and my biggest ambition is to build a ‘universal physics teacher, who taught me the power of HOW DO YOU OVERCOME laser machine’ that can do different jobs and is science. Using nothing but imagination, logic OBSTACLES IN YOUR WORK? accessible to the public. I like to think of this and perhaps a piece of paper and a pencil, Learning from others. The majority of as a personal workshop which ordinary people Newton was able to declare a law that every problems can be solved using my own could use to build the parts they need in a way object in the universe must obey. I became knowledge and experience, but once in a while as simple as clicking a few buttons.

PhD student Ankesh Todi is testing an adaptive optics device to modify the High school student Myles Wirt is testing a laser 3D printer during a spatial shape of a laser beam. summer internship in Xiaoming’s lab.