People behind the PICs | The Photonic Integrated Circuits (PIC) industry is booming. Companies in the field are growing steadily, start-ups with innovative solutions are popping up regularly, and the search for technical staff seems never-ending. In this interview series, we are curious to get to know the people behind the PICs. Who are the energy forces driving this technological revolution, and what motivates them? What can future photonics engineers expect from a career in this field?
Wenjing Tian vividly recalls performing her first optical interference measurement in a dark lab at Beijing University of Posts and Telecommunications, where the room was suddenly illuminated by mesmerizing patterns of light, sparking her passion for photonics. At the Institute of Semiconductors, she familiarized herself with Photonic Integrated Circuits (PICs) based on the silicon photonics platform. Her next challenge? A PhD in hybrid photonic integration in the Photonic Integration research group at Eindhoven University of Technology. For her research, she combined the unique advantages of different material platforms: indium phosphide and silicon nitride. As a Postdoc in this group, she pushed the boundary further by not just integrating different photonic technologies, but integrating photonics with electronics. Nowadays, she is thriving in her new role as Researcher at IMEC.
Wenjing Tian, Researcher at IMEC. Photography by Bart van Overbeeke.
What made you decide to do a PhD in PICs and pursue a career in this field?
“I was always fascinated by optics and photonics. In my bachelor, we performed an optical interference measurement using a red laser. When the light went through the gratings, it lit up the room with dazzling patterns, like stars in the sky.. I thought it was truly amazing. So, in the final year of my bachelor, I started studying semiconductor physics to learn more about this. What interested me is that this technology powers a big variety of applications and functionalities. It felt very concrete, and it took me to the Institute of Semiconductors, where I studied silicon photonics. To this day, I am still intrigued by how we squeeze these bulky components onto a tiny, tiny chip.”
What was the topic of your PhD? How did you develop your ideas and find focus?
“In photonic integration, we use different kinds of materials to make a PIC. Each material has its own unique advantages. In my PhD, we combined the unique advantages of indium phosphide and silicon nitride: what we call hybrid integration. The goal of my project was to improve the efficiency and performance of hybrid PICs while supporting a large number of optical and electrical connections. Especially once a circuit gets bigger and device functionality gets more complex, you need a lot of optical channels to bring the optical information in and out of the chip. Not only is this needed due to an increasing demand for applications, it is also the key to upscaling the production of PICs.
As my PhD program consisted of two research projects working together, it was definitely a challenge to find focus. One project was very application-driven, with the aim at transferring knowledge and technology from academia to industry. The other project was in collaboration with Microsoft Research. They wanted to jointly create advanced PICs to power their data center. So next to doing research, the goal was also to solve a real-world problem. I really liked that applied approach. It was quite different from my master’s, where I worked on more exploratory projects that were not expected to reach the market for another five to ten years.
Hybrid photonic integration has many aspects, not only on device level but also on system level. There is a lot of interfacing between different technologies. In the meantime, I needed to increase my knowledge of applications like optical communication and data centers. My work was spread out across three cleanrooms—at TU/e, SMART Photonics, and LioniX International—as well as two assembly foundries, ficonTEC and PhiX assembly. Managing work across multiple facilities presented technical challenges and tested my soft skills, as coordinating with different teams and environments added to the complexity. Working with just one cleanroom is already quite challenging!”
As a Postdoc at TU/e, what projects did you work on?
“The reason I chose my Postdoc project in the Photonic Integration group is because it closely aligned with my research interests in hybrid photonic integration and was strongly linked to my PhD work. I got to bring my research to the next level by not just combining different photonic technologies, but combining photonics with electronics. It was the perfect opportunity to explore different photonic and electronic platforms, deepen my understanding of circuit design, and learn about assembly and packaging between electronics and photonics. From a technical view it was exciting for sure, as I moved from the generic indium phosphide platform to the IMOS platform. It was an application-driven project targeting telecom and terahertz applications.
Additionally, I gave lectures on PIC design as part of the JePPIX PIC Design Course. This experience not only allowed me to stay updated on the latest industry trends but also helped me refine my communication and teaching skills, which I believe will contribute to my research and future collaborations.
Next to technical skills, I was eager to develop my project management and communication skills. I believe they are key qualities to have in both academia and industry. My role involved assisting with communication and coordination. With 64 partners involved in the project, it presented an exciting challenge. While I did not directly collaborate with all 64 partners, this setup provided valuable resources and opportunities to engage with potential future collaborators on other projects. I was excited to learn from a diverse range of people and bring valuable insights back to our research group.”
How do you experience the European PIC ecosystem?
“The established ecosystem we have here was one of the main reasons I wanted to do a PhD in Europe. Academia and industry are closely tied in the Netherlands. It is encouraged on a national level to bring science from the university to the market. At conferences, I frequently encounter application-focused talks on topics such as agriculture, medical care, and space applications. This level of crossover was less common when I was studying in China. I really value the work that JePPIX and ePIXfab do; they integrate all the resources together. If I reach out to JePPIX, I get to know the structure of the ecosystem. I know where to go to realize functionality on my chip, from the initial design stage to the final testing. And since we are in the Brainport region here, there are lots of start-ups and big companies where you can find a related job.”
Wenjing Tian, Researcher at IMEC. Photography by Vincent van den Hoogen.
Is there somebody in the photonics industry that inspires you? And why?
“The first person I think of is my PhD supervisor Xaveer Leijtens. I learn from our collaboration every day, not only on a technical level. The way he interacts with people and approaches challenges with humor is truly inspirational. Meint Smit is another name that pops up in my mind. I am amazed at how he laid the foundations of the photonic integration community here in Eindhoven. We call him the godfather of photonics. He is still actively participating in research activities because he has such a passion for the field. In one of his articles, he mentions Hofstadter’s Law (the law of pi:), which states that completing a complex task always takes longer than you expect, even when you already take Hofstadter’s Law into account. I feel relieved that even prestigious professors acknowledge that you always need more time and effort to achieve something.
Another person that inspires me is Marija Trajkovic. She has a technical background and is using her knowledge and experience to coach people that are currently doing a PhD. Her willingness to help others motivates me to do the same. There are so many other people that I find inspiring, probably too many to mention here!”
You recently started a new job at IMEC. How would you describe your role? And do you see yourself working in the PIC industry for a long time?
“I am excited to have joined IMEC as a researcher, specifically as a project lead in laser integration. IMEC’s innovative environment and focus on advancing photonic technologies align well with my research experience in hybrid photonic integration. In this new role, I am able to apply my skills in combining photonic and electronic platforms to projects with real-world applications in areas like telecom, automobile and high-speed data communication. I am looking forward to the opportunity to work with a multidisciplinary team and explore advanced photonic technologies on a broader scale, contributing to both research and industry-driven solutions.
Longer term, I aim to continue advancing photonic integration, ideally in roles that bridge research and application, allowing me to drive innovation in ways that impact multiple sectors. At the end of the day, I love doing research and I am passionate about the collaborative and dynamic environment we have here. Eindhoven is a true photonics hub with fantastic resources and facilities, providing everything a researcher needs to grow and thrive. While I have enjoyed my time here immensely, I am also excited about the prospect of exploring other cities and countries that are driving photonics research forward. Expanding my horizons internationally will not only deepen my technical expertise but also give me fresh perspectives and new opportunities to contribute to the global photonics community. In short, I love photonics way too much to ever leave it behind!”
Do you have any tips for people starting out in the field of photonics, or things they should keep in mind?
“If you are doing a PhD in photonics or are planning to do so: stay motivated, stay ambitious, and stay patient. Those are the top things I want to recommend. If you feel confident, try to multitask and challenge yourself by going out of your comfort zone. For example, after you design your circuit, rather than purely waiting for the chip to be fabricated, you can increase your measurement skills or learn about applications. Keep yourself busy. And always prepare a plan B. When I started in my second year, I realized I needed a plan B. In hindsight, it would have saved me time if I would have been more initiative earlier. There are so many experts in the photonics community to reach out to about your interests and plans. People love to help. And there are lots of educational resources as well, such as the JePPIX PIC Design Course. Keep an eye out and don’t be afraid to ask for help.”
Curious about what job opportunities the photonic integration community has to offer? Check out our career page.