I, Scientist | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Afterword
The first time I heard of the field of *photonics—for studying photonic properties of matter—*was from a college research program I was selected to join by the physics department; professor Wei-Chih Liu as my mentor introduced me to it. From there on, I proceeded to learn related subjects and necessary numerical skills in order to carry out a research project independently. Due to the parallel among many ideas, I also learnt *condensed matter physics—for studying electronic properties of matter—*at the same time. Below are some highlights of my ten years as a theoretical photonic & condensed matter physicist.
The technological contributions from modern condensed matter physics was immense. Without it, we wouldn’t have computers or pretty much any electronic devices. All those modern creations made possible due to the maturity of precise manipulations of how electrons flow in semiconductors. Unlike electricity from the power line (independent free electrons that flow under voltage gradient), the elections in a semiconductor can be grossly understood as two distinct populations: a massive subpopulation with electrons endowing wave-like property that collectively form a reconfigurable substrate for another smaller subpopulation to ride on. Because the first subpopulation can be reconfigured by applying voltage, it affects how freely (how conductive) the second population can move as an ordinary electric current.
The reason semiconductor has such a tunable conductivity is because its electrons are placed on a perfect grid—a crystal—so that individual wavefunctions added up to form many non-overlapping energy states.
If we apply the same logic, one should be able to manipulate light the same way by engineering something call “photonic crystal.” One unique feature about engineering “light matters” is the use of broad range of wavelengths which translated into the many desired periodicity of corresponding crystal. So, the engineering challenge of making an “visible-light crystal” would be different from the challenge of making a “microwave crystal.” This diverse scales in wavelength makes photonics such a versatile engineering field.
In addition to its engineering aspect, photonics can also be very theoretical. And it was this theoretical aspect that attracted me to the field. Some phenomena that once thought impossible for a naturally-occurred materials, one after another, was proposed theoretically and realized experimentally. These materials that was considered beyond nature were named “metamaterials”. To name a few:
Not only those which mainly manipulate photons, some metamaterials have their mechanical vibrations—a phonon—at extremely high-frequencies. With these phonons vibrating at the same frequencies as the operating photons, one can manipulate their coupling to create even more mind-boggling phenomena.
Most of my researches that had some connections with the above phenomena are collaborative works with experimentalists. But what really kept me in Shvets Lab at UT-Austin are my wonderful theoretical projects regarding the invention of photonic topological insulators, which, at that time, was the last electronic phenomenon on the list from condensed matter physics to be realized photonically.