Ultrashort-pulse fiber laser reaches unprecedented performance at Cornell

ITHACA, N.Y. – Cornell University researchers have engineered a new kind of environmentally-stable fiber laser that generates high-power ultrashort light pulses, opening new possibilities and applications for the fiber source.

The fiber laser produced approximately 50-nJ and 40-fs pulses, which yield a peak power of one megawatt, an order of magnitude higher than that of previous lasers made with similar fiber. Moreover, this laser is insensitive to environmental perturbations, which is a desirable feature for applications such as micromachining, imaging, and clinical treatments. The results are detailed in the paper “Megawatt peak power from a Mamyshev oscillator” published in the latest edition of the journal Optica.

By making the continuous wave lasing threshold above the threshold for mode-locking, the research team, led by Ph.D. student Zhanwei Liu in the Wise Research Group, designed a Mamyshev oscillator to support stable mode-locking with huge nonlinear phase shifts. To harness this nonlinearity for the generation of clean, high-energy ultrashort pulses, the oscillator was engineered to support parabolic pulse formation.

Numerical simulations reveal key aspects of the pulse evolution and realistically suggest that peak powers that approach 10 megawatts will be possible with ordinary single-mode fiber. With further development, this kind of laser should find applications ranging from material processing to surgery.

“This kind of laser is very attractive for practical applications, and now we have shown that it is capable of even better performance than existing short-pulse fiber lasers,” said Liu, adding that he plans to continue research and optimization of the oscillator.