Transmission properties of the femtosecond pulse through a near-field optical fiber probe

The experimental results are given on the broadening characteristics of the time and frequency profile of the femtosecond pulse passed through a SNOM fiber probe. The power threshold for the spectral and temporal broadening is 158 μw for pulses with 250 fs width and the repetition rate of 250 kHz at 830 nm wavelength. The time broadening reaches 1 ps for 250 fs incident pulse of 500 μw. A finite-difference time-domain (FDTD) simulation is carried out to illuminate the transmission properties of ultrafast pulse through the SNOM probe. The broadening influence on temporal resolution spectrum and near-field fluorescence excited by two-photon technique are discussed.