Femtosecond pulse compression using negative-curvature hollow-core fibers

In order to compress femtosecond ultrashort pulses a novel fiber called negative-curvature hollow-core-fiber, is investigated and is used to compress the output of a Ti: Sapphire laser. Firstly, a hollow-core-fiber with circular tubes cladding is introduced, and the loss parameter is calculated with the Finite Element Method and the calculated results are compared with the experimental results. Following this the evolution of an ultrashort pulse along the fiber is simulated in the General Nonlinear Schrodinger Equation. At last the compression experiment using NC-HCF is conducted. The 160 fs output of a Ti: Sapphire laser is coupled into the fiber with high-pressure Argon. An output of 84 fs is achieved which is the result of the balance between anomalous dispersion and self-phase modulation in the fiber. The experimental results matched the simulations. This novel fiber, which has the advantages of a high damage threshold, low and adjustable dispersion and nonlinear coefficients, is a promising material in the field of ultrafast optics.