An integrated blue laser combines low noise with fast tuning

A Nature Photonics paper published on October 22 demonstrates an integrated blue laser near 461 nanometers. It couples a gallium-nitride diode to a silicon-nitride microresonator and uses piezoelectric actuators to tune the frequency.

The researchers report a linewidth below 30 kilohertz and rapid, continuous frequency chirps. Their demonstrations include underwater optical communication and aerosol sensing.

This is an enabling light-source result rather than optical arithmetic. Compact, stable and controllable sources matter to broader photonic and quantum systems, but usefulness in a particular processor still depends on wavelength, power and integration requirements.