Materials engineer and photonics expert Allan Shih-Ping Chang is a principal scientist at the Lawrence Livermore National Laboratory in California. Photo by Blaise Douros Written by Wright B. Señeres Oct. 8, 2024 Allan Shih-Ping Chang, a 2004 Princeton graduate alumnus, brings a longtime fascination with materials science to his work on solutions for climate change and clean energy. Now the principal scientist of the optical sensing group at the Lawrence Livermore National Laboratory, Chang is working to clear the path to widespread adoption of hydrogen as an everyday power source. Stationary hydrogen tanks and fuel cells are growing in popularity as primary and backup sources of energy for residences and businesses. But hydrogen leaks can be highly flammable in air, so continuous monitoring through early detection systems is critical. Chang and his collaborators are working to commercialize a fiber-optic sensor for quickly and directly detecting and locating minute hydrogen leaks, an enabling technology that could remove one of the largest safety hurdles for widespread hydrogen energy.His current work in fiber optics traces back to his time as an undergraduate at the University of Melbourne. He was drawn to photonics, a branch of physics that explores the use of light to transmit and process information, and started working on an optical control system research project, but his initial experiments kept failing. His mentor at Melbourne determined that a semiconductor device in his setup was contaminated with impurities. “He said you better look into it, and look into it I did,” said Chang. While investigating the semiconductor device, he realized that materials science and its place at the intersection of physics, chemistry and engineering helps us understand how things work. “Or not!” said Chang. Chang then became fascinated with the ability to engineer materials to achieve desired properties and functions. While at the University of Michigan for a master’s degree, he noticed the work in nanoimprint lithography at Princeton that Stephen Y. Chou, the Joseph C. Elgin Professor of Engineering, was pioneering. Chou and colleagues around campus developed methods of fabricating nanometer-scale patterns previously hard to attain, often for use in new electronic and optical devices. “Among others at Princeton, he was the one who opened my eyes and influenced my research values the most,” said Chang.He credits Chou, his Ph.D. thesis advisor and also an associated faculty member of the Princeton Materials Institute, with developing an open-minded, interdisciplinary approach to research. “Experience often distills into values that endure,” said Chang. “Over the years, these values I learnt at Princeton have profoundly helped me to tackle technical and professional challenges, and to boldly go into fields I never imagined I would be in.”While Lawrence Livermore is part of a group of national labs tasked with nuclear security research, its overall mission is much broader. This has given Chang opportunities to apply his materials science expertise to nuclear nonproliferation monitoring and verification, materials for fusion energy applications, climate change mitigation and clean energy. Through programs by the Department of Energy, Chang is developing this fiber-optic gas sensor and associated sensor network technology, which he calls his biggest current project, in collaboration with internal teams at Lawrence Livermore and several academic, federal and industry partners in the U.S. and Europe. “Ultimately, our work aims to help advance mitigation of climate change and transition to clean energy,” said Chang.