Dr. Dragic from the University of Illinois has developed an optical fiber for high-powered fiber laser applications.  This fiber is specifically designed with the thermal mode instability problem in mind.  This fiber remains single-moded at normal operating temperatures, which enhances beam quality and power efficiency of the laser. 

 By doping the fiber core with a specific composition of rare-earth fibers, the refractive index of the core increases more slowly with increasing temperature, when compared to the refractive index of the cladding.  This effect allows the optical fiber to maintain single-mode transmission at high temperatures.

Benefit

Improves energy efficiency of high-power fiber lasers.