In the vast world of optics, where the boundaries between materials science and engineering continue to blur, alumnus Juhwan Ko is now shaping the future of optoelectronic semiconductor technology at one of the world’s leading research institutions, MIT.

We had the opportunity to speak with him about the valuable achievements he gained through the challenges of graduate school and his heartfelt advice for younger students.

Q1. Hello, Dr. Ko. Could you briefly introduce yourself?

Hello. My name is Juhwan Ko, and I received my Ph.D. in 2024 from Professor Youngmin Song’s laboratory in the School of Electrical Engineering and Computer Science at Gwangju Institute of Science and Technology (GIST).

Currently, I am working as a postdoctoral researcher at MIT in the United States, where I continue the optics research I pursued during my doctoral studies. More specifically, I am conducting in-depth research on epitaxial optoelectronic semiconductor technologies.

Q2. What research topic did you mainly focus on during your Ph.D. program?

My research primarily centered on the interaction between light and matter. Because light possesses both wave-like and particle-like properties, its applications span a wide range of fields, including displays, sensing, energy devices, and optical computing.

In particular, I focused on building active photonic systems using active materials, whose optical properties change in response to external energy inputs. I also concentrated on heterogeneous integration technologies, directly integrating optical devices with commercial addressing platforms such as CMOS and TFT systems.

Q3. What was the most rewarding or memorable moment during your research journey?

I majored in materials science and engineering as an undergraduate and later entered the School of Electrical Engineering and Computer Science for graduate studies. Because I changed my field, I initially faced difficulties, having to relearn fundamental optical theories such as wave equations from the beginning. However, this challenge eventually led me to establish a unique goal: integrating materials science with optics. Later, I was able to establish active material-based optical modulation technology, and the first moment I witnessed the color of a microdisplay physically changing in response to electrical energy, I felt a profound thrill as a researcher.

That experience gave me strong confidence in my research direction. It also led not only to academic publications but also to achievements such as the Samsung Humantech Paper Award andion for the Sejong Science Fellowship, making it an immensely rewarding journey.

Q4. How did you usually relieve stress during your Ph.D. program?

A Ph.D. program often involves a very long cycle before one can feel a sense of accomplishment. In many cases, even after investing significant effort into research, the work may not lead to successful results or publications. This was one of the most difficult aspects for me. To cope with this long cycle of achievement, I tried to create opportunities for smaller, more frequent accomplishments. For example, activities such as marathon running and playing soccer helped me relieve stress while providing a steady sense of small achievement.

Q5. Was there a special reason you chose GIST for graduate school?

During my senior year of college, I had the opportunity to do an internship at GIST, and I personally experienced how outstanding its human and physical research infrastructure was. At the time, I only had a vague curiosity about research rather than a clearly defined goal. However, I felt that I wanted to explore research more deeply rather than entering the workforce immediately, which ultimately led me to choose GIST.

Q6. What was your actual graduate life at GIST like?

In one phrase, it was a time filled with the full spectrum of joy, anger, sorrow, and happiness. I sometimes joke that it was even more demanding than military life because the path toward achievement is often long and difficult. It was especially discouraging when carefully prepared experiments or manuscripts did not produce the expected outcomes.

However, GIST is an ideal place for immersing oneself in research. The campus is peaceful, and the surrounding environment offers plenty of opportunities to regain a sense of calm and balance. Being able to explore areas outside the campus and enjoy the relaxed atmosphere was also a major advantage.

Above all, the campus layout is highly efficient for research collaboration, and compared with other research institutes or universities, I believe this is one of GIST’s unique strengths.

Q7. How did you come to join MIT, and what are your future career goals?

As I searched for institutions leading the field of heterogeneous integration, two places stood out to me: the University of Oxford in the UK and MIT in the United States. After completing my Ph.D., I directly reached out to research groups whose directions aligned with my own goals. Through this process, we confirmed strong mutual synergy, and fortunately, I was able to join MIT. At present, I am laying the foundation for my research at MIT. In the long term, my goal is to lead my own research team, develop photon-based computing systems, and nurture experts in this field.

Q8. Do you have any advice for juniors considering graduate school?

Investing five to six years in research is never an easy decision. It is natural to feel anxious when hearing news about peers getting jobs or getting married. However, the sense of accomplishment gained through research is incomparable. Rather than being overwhelmed by vague fears, I strongly recommend experiencing the full research process at least once through an internship or a master’s program, especially the complete cycle of writing a paper from beginning to end. That experience will help you determine whether this path suits you and whether the sense of achievement from research aligns with your personality. Graduate school is not simply a place where you are confined to a laboratory. It is a space where you grow into a professional researcher.

I hope you see it as a unique opportunity to experience professionalism and personal growth at a young age. Finally, I would like to emphasize two essential languages: English for communication and Python for data analysis and skill development. If you prepare these two languages well, they will be invaluable assets in any field of research.