If you want to admire the beauty behind the 2016 Nobel Prize in Physics – topological phases of matter, take a course in topology, followed by graduate-level solid state physics. But if you ask for a concrete application of this topic, you now have an excellent example. Harnessing the concept of topology, scientists have engineered a new way to channel light in lasers.
Originally a mathematical subject, topology examines geometric objects and captures the essence of what remains unchanged when they smoothly transform into one another. For example, a hole remains when a coffee mug transforms into a donut. Physicists use topology as a powerful tool to categorize complex systems using a single integer. When a system is described by the right integer, the details and imperfections of the material no longer matter. Instead, perfect channels emerge. Systems with such topologies have long been studied in solid-state electronics, with numerous scientific fruits yet few practical applications.
A decade ago, Marin Soljačić at MIT brought this wave of creativity into the field of photonics and sparked interests in topological systems for light. Recently, a team led by Mordechai Segev at the Technion Institute in Haifa, Israel, and his collaborators at the University of Central Florida in Orlando, used topological photonics to create a laser beam that is more robust against defects and significantly more efficient.
Given lasers’ wide applications – ranging from printers to barcode scanners, from surgeries to free-space communication – this breakthrough in laser efficiency could bring tremendous commercial value. Furthermore, because of their flexible platform to engineer wave patterns, these photonic systems will be another wonderful playground to study topological physics, complimentary to solid-state electronics.
Original Research Article:
Topological insulator laser: Theory– Science
Topological insulator laser: Experiments – Science