CU Boulder engineers develop ultra-low loss chalcogenide microresonators using highway-inspired "racetrack" design

Researchers at CU Boulder use highway-inspired curves to create ultra-low loss optical chips. Discover how these microresonators will power future quantum sensors.

By: AXL Media

Published: Feb 24, 2026, 8:11 AM EST

Source: The information in this article was sourced from University of Colorado at Boulder

The Breaking Development

A research team at CU Boulder has successfully engineered a new generation of optical microresonators that significantly reduce energy loss in photonic circuits. These microscopic structures are designed to confine light within a small space, increasing its intensity to levels necessary for advanced sensing and optical processing. Lead author Bright Lu, a doctoral student in electrical and computer engineering, noted that the primary goal of the project was to achieve these high-intensity states using substantially less optical power, which is critical for the development of future portable navigation and chemical detection sensors.

Background and Context

Microresonators function by trapping photons in a loop, but their efficiency is often hindered by "bending loss," where light escapes as it navigates corners. To solve this, the researchers looked toward large-scale civil engineering, specifically the Euler curves used in railway and highway design to manage centrifugal force. By replacing sharp turns with gradual, smooth transitions, the team ensured that light remains confined within the circuit. This innovation allowed the devices to reach "resonance" more effectively, a state where light becomes trapped and its power is amplified significantly.

Key Players and Stakeholders

The project was a collaborative effort involving experts from various disciplines, including Won Park, the Sheppard Professor of Electrical Engineering, and Professor Juliet Gopinath. The fabrication took place at the Colorado Shared Instrumentation in Nanofabrication and Characterization (COSINC) facility. Physics PhD student James Erikson led the testing phase, utilizing precision lasers to measure how light interacts with the resonators. This decade-long collaboration between engineering and physics departments was essential for overcoming the technical hurdles associated with sub-nanometer fabrication.