Intensity–phase characterization of white-light continuum generated in sapphire by 280 fs laser pulses at 1053 nm

A white-light continuum is generated in bulk sapphire using 280 fs, 1053 nm centre wavelength pulses at peak powers well above the critical power. The resulting spectrum extends from 400 nm up to at least 1100 nm with good conversion efficiency. A high-pass filter is used to remove the residual peak at the pump wavelength, producing a broad, flat spectrum in the near infrared region. We characterize the intensity and phase of the continuum by using cross-correlation frequency-resolved optical gating. We show that using pump pulses above 1 µm is a very interesting approach for generating broad continua with favourable characteristics. (paper)