Polariton: Hello Guillermo, thank you for taking the time for this interview.   
Prof. Carpintero: Thanks to you! I am very much honored to be in the same league as Jürg Leuthold.

POL: You lead the Optoelectronic and Laser Technology group and UC3M, what are the research topics in your group at UC3?  
GC: Currently I co-lead the opto-electronic and laser technology group, together with Prof Lamela who founded the group back in 1994. In the group I lead the research lines on millimeter-wave and Terahertz (THz) photonics and Photonic Integrated Circuits (PICs). I worked with the photonic integration pioneers at the time of the EPIXNET (a European network of excellence), participating in the firsts trainings organized by JePPIX. We pioneered integrated microwave photonics and now have expanded into aerospace because of the size reduction and low-power dissipation of PICs.

POL: And you are based in Madrid. What do you like from the research ecosystem here?  
GC: Madrid is a very vibrant city, with a great number of companies, which attracts good people from around the world. We have received great researchers from around the world, from Prof. Tadao Nagatsuma, Prof. Zoya Popovic, Prof. Antti Räisännen all of whom have spent 6 months. Also, Madrid, having five public universities in a small area creates a very enriching environment. UC3M, being the second youngest university in Madrid, and a small one, encourages collaboration across disciplines.

POL: Is there a research achievement that you are particularly fond of?  
GC: There is a very recent one, that is starting LeapWave technologies, a spin-off. Spain is a country known by its creativity in arts, and I always wanted to show we are also creative and innovative in technology. I have been able to gather an extremely amazing team in which we are aiming for radical innovation in the field of radiofrequency with a new range of broadband interconnects. If I look back, I like to remember the FP7 iPHOS project, which was my first research project, and was a European project which I coordinated. A step that changed my career and finally led me to start a spin-off 22 years later.

POL: Then, after some time, you started your own company. What was your motivation?  
GC: As I said, the group had amazing postdocs, who were part of key developments leading to exploitable patents, who needed a life outside of academia. At the same time, very bright colleagues outside academia were ready to start a company, and this was the key factor. Then, finding some very supportive investors completed the picture. It was as if we were meant to do it at that precise moment. In this effort, we have to thank the great support we receive from our investors, we are technical people and needed help to work our way to start our company in Spain, which is quite bureaucratic. Now we are on our way to contribute with our technical creativity Made in Spain.

POL: How did you get to know the other Founders?  
GC: Alex is a key person, a former postdoc from a dear colleague in the radiofrequency group, Prof. Luis Enrique García. Daniel and Muhsin were postdocs in my group, with amazing skill in lab and radiofrequency design and assembly respectively. Then we drafted Alvaro who had gained experience working in German and Spanish companies in photonics, keeping in mind that he and I had wanted to start a business for a long time. So, we decided to embark into this romantic adventure, and immediately realized we needed an electronics expert. I had to convince one of my best friends, an electronics wizard, of the opportunity and got him onboard. And you will agree that choosing the people is the key to success, as you care about the skills and the team spirit.

POL: How do you cope with your dual role as professor and as part of the company leadership?
GC: I am still learning to live in this duality, but I am quickly learning that the best way to have clean boundaries between the roles is to delegate and empower people on both sides. This is very important because we all grow by assuming responsibilities. People need space to grow and I needed to limit my own influence on both sides.

POL: Can you tell us something about LeapWave that nobody knows?
GC: So something that nobody knows and is not a secret? (laughs … thinks) Deciding for the company name was not so easy, and at a certain point we went with a shortlist to the Spanish authorities. We wanted to avoid the use of Tera, it’s overused, and anyway not broadband enough (laughs again). Guess what? The authorities pruned that list radically and the current name LeapWave was not on that list. So the name was not decided early in the process, but luckily the administration are UC3M added some delay on their own which gave us some extra time.

POL: Let’s come to the relation between LeapWave and Polariton? What can the two companies achieve together?
GC: LeapWave would like to explore mm-wave receivers, which is an unsolved problem. The existing electronics are modest and the performance is poor. So I came across plasmonic devices which have been proven to work well above the 100 GHz mark, and considered that our broadband connectors could be a puzzle piece for them. The cooperation with Polariton is natural for LeapWave. By combining the two technologies we will contribute for better and more reliable 6G links.

POL: 6G is the magic word. How do you think Polariton in going to impact the 6G applications?
GC: I think that Polariton will be a key player to fill the gap. I know of no other PICs with that bandwidth. With measurements up to 500 GHz we have the headroom for many interesting products.

POL: Thank you for sharing your view on this. Finally, what do you like to do when you are not working?
GC: I like to wander around with no specific destination. As long as it is outside. I learned this from my grandfather, who liked to do it as well. Later, I realized that we often would end up in one of his favorite tasca (=tavern). So there was a destination. And, another reason to cultivate this wandering is for some quality time with my wife.

POL: Thank you again for your time and pleasant chat.

Interview by Stephan Koch.