The Computer Science Faculty building at Technion University in Haifa, Israel.
(photo credit: BENY SHLEVICH/WIKIMEDIA COMMONS)
Lasers have been with us for years, but now researchers at Haifa’s Technion-Israel Institute of Technology and colleagues in the US and Singapore have reported a breakthrough with the potential to “revolutionize” semiconductor lasers and precise sensors.
The journal Science reports in two separate articles that the team has developed a topological insulator laser with significantly greater efficiency and stability than similar laser systems. This, they say, paves the way for a powerful coherent integration of multiple laser units.
The “groundbreaking” study was headed by the Israel Prize laureate Prof. Mordechai Segev of the Technion’s physics faculty and included Prof. Demetrios Christodoulides and Prof. Mercedeh Khajavikhan at the University of Central Florida.
Several years ago, the same Technion group introduced these ideas in photonics and demonstrated a Photonic Topological Insulator, where light travels around the edges of a two-dimensional array of waveguides without being affected by defects or disorder. Now the researchers found a way to use the properties of photonic topological insulators to build a new type of laser with a unique fundamental behavior that greatly improves the robustness and the performance of lasers arrays, opening the door for a vast number of future applications.
“This new laser system went against all common knowledge about topological insulators,” said Segev.
“In a nutshell, the unique robustness properties of topological insulators were believed to fail when the system contains gain, as all lasers must have,” he continued. “But we have shown that this special robustness survives in laser systems that have a special (“topological”) design and is able to make the lasers much more efficient, more coherent and at the same time immune to all kinds of fabrication imperfections. This seems to be an exciting avenue to make arrays of miniature lasers work together as one: a single highly coherent high-power laser.”
The topological isolation laser is based on ordinary materials in the semiconductor world, without the need for magnetic fields or unique magneto-optical materials and therefore can be easily integrated into many different optical and electronic devices.
“In recent years, we have found new ways to control light in an unprecedented way, and here we have cleverly fooled photons so that they feel as if they are in a magnetic field and as if they have spin,” added Hajavikan.
The current research presents the first successful combination of two different fields of physics – lasers and topological insulators. Topological insulators, which stood at the heart of research that resulted in the winning of the 2016 Nobel Prize in Physics, constitute a new state of matter. They were first discovered for electrons in solids and are characterized by their insides acting as insulators (not conducting electrical current).
Segev concluded: “This is my most important research so far. The new laser system refutes everything we knew about topological insulators. This is a major breakthrough in basic science, and to my delight, it also has many practical implications.”
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