Self-phase-modulation-induced spectral broadening of laser pulses in air-guided modes of hollow photonic-crystal fibers (PCFs) is shown to allow the creation of fiber-optic limiters for high-intensity ultrashort laser pulses. The performance of PCF limiters is analyzed in terms of elementary theory of self-phase modulation. Experiments performed with 100 fs microjoule pulses of $800\mathrm{nm}$ $\mathrm{Ti}$:sapphire laser radiation demonstrate the potential of hollow PCFs as limiters for $10\mathrm{MW}$ ultrashort laser pulses and show the possibility to switch the limiting level of output radiation energy by guiding femtosecond pulses in different PCF modes.

• Received 14 March 2004

DOI:https://doi.org/10.1103/PhysRevA.70.023807