Anti-Stoked fluorescence pumping for cooling single-frequency fiber lasers

Purpose and goal:

The project increased scientific impact in optical cooling thorough investigations of specialty Yb-doped optical fibers and high-accuracy fiber temperature sensors. This result culminated with the development of laboratory prototypes of radiation-balanced (or athermal) fiber lasers and amplifiers. The project involved effective international collaborations, fostering the exchange of scientific knowledge and promoting Mid Sweden University’s internationalization.

Expected results and effects:

This project created an efficient radiation-balanced Yb-doped fiber laser with a record output power (nearly 200 mW), as well as the world´s first single-frequency radiation-balanced fiber amplifier. This was achieved by increasing the absolute accuracy of a custom slow-light temperature sensor, then testing many custom fibers, and optimizing the laser/amplifier itself (fiber length in particular).

These advances are expected to benefit fields reliant on high-purity, high-power light, like laser fusion, gravity-wave detection, microwave photonics, and advanced metrology Approach and implementation:

The project had a clear structure and good planning of the resource allocation and technical development. The results showcased effective collaborations and milestones in the development of (1) specialty fibers with record-high Yb doping, (2) a temperature sensor with enhanced precision, and (3) radiation-balanced fiber lasers and fiber amplifiers. Challenges were overcome through innovative solutions, and valuable lessons were gathered for future projects.