Abstract

Diffraction-limited beams of femtosecond laser pulses are widely used in many scientific and technology fields. Delivery over fiber lengths of the order of meters of such pulses is critical, for example, for applications such as in situ multiphoton microscopy. Due to dispersion and nonlinear effects, pulses propagating in fibers are typically severely distorted and temporally broadened. Several delivery schemes were proposed to preserve the duration of the output pulses.¹'² In all these schemes single mode fibers (SMFs) are used to insure high spatial quality of the output beam. As a result of the small core size of the SMF, nonlinear effects limit the energy of the pulses that can be delivered and yet still remain in the femtosecond regime. Recently developed microstructured fibers (MF)³ offer new possibilities for delivery of such energetic pulses. Utilization of large-mode-area single-mode MF is not possible due to prohibitively large bend losses, ⁴ however robust single-mode operation of multimode MF appears attainable.⁵

© 2002 Optical Society of America