Researchers at the University of Colorado Boulder have developed ultra-efficient chip optical sensors, marking a significant advancement in sensor technology. These sensors, known as microresonators, are tiny devices capable of trapping and intensifying light, enabling unique optical operations. The team, led by Bright Lu, a doctoral student in electrical and computer engineering, focused on 'racetrack' resonators, which are elongated in shape, resembling a running track. To minimize light loss, they employed 'Euler curves', a type of smooth curve also found in road and railway design, ensuring light is guided smoothly through the resonator. This innovation allows photons to circulate longer and interact more strongly inside the device, enhancing performance. The microresonators were fabricated using the Colorado Shared Instrumentation in Nanofabrication and Characterization (COSINC) clean room's new electron beam lithography system, providing a highly controlled environment for microscopic work. The researchers utilized chalcogenides, a family of specialized semiconductor glasses, for their high transparency and nonlinearity, resulting in one of the best-performing devices using these materials. The fabrication process, involving the creation of thin films of glass into working optical circuits, was a fulfilling aspect of the project. Once fabricated, the microresonators were tested for their ability to trap and transmit light, with the results indicating deep and narrow resonances, a key indicator of device quality. The team, including James Erikson, a physics PhD student specializing in laser-based measurements, carefully aligned lasers with microscopic waveguides to monitor the behavior of light inside the device. The microresonators have a wide range of applications, from compact microlasers and advanced chemical and biological sensors to tools for quantum metrology and networking. The ultimate goal is to create a device that can be handed to a manufacturer and mass-produced, revolutionizing various industries.
