EPFL demonstrates chip-scale blue laser with rapid frequency control

EPFL researchers demonstrated a chip-scale blue laser that combines stable emission with rapid electronic frequency control, with laboratory tests showing underwater data transmission and smoke detection. The device connects a conventional blue laser to a microscopic ring that selects a frequency and feeds light back into the laser. Voltage-driven aluminum nitride components adjust the ring through mechanical stress. One configuration achieved a linewidth below 30 kilohertz; another tuned across more than 900 megahertz, repeating adjustments up to 1 million times per second. The underwater test reconstructed an image transmitted through 30 centimeters of water. The smoke experiment detected airborne particles but did not measure their concentration.