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

Abstract

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.

Ultrafast supercontinuum generation in bulk condensed media

“…In the visible spectral range, using the second harmonics of an amplified Yb-fiber laser (515 nm) as a pump, the SC spectrum from 340 nm to 650 nm was measured, which was thereafter used to seed the noncollinear optical parametric amplifier pumped by third harmonic (343 nm) of the same laser, rendering unprecedented tuning in the near-ultraviolet and blue spectral ranges 204 . A typical SC spectrum in sapphire covers the wavelength range from 410 nm to 1100 nm, as generated with fundamental harmonic pulses from Ti:sapphire laser (the pump wavelengths of around 800 nm) and measured under the commonly used operating conditions (the input pulse energy of ∼ 1 µJ and the material thickness of 1 − 3 mm) 26,28,30,205 . A notable extension of the infrared part of the SC spectrum was demonstrated by employing looser focusing geometry and somewhat longer sapphire samples; under these focusing conditions an appreciable red-shifted SC signal extended to more than 1600 nm 26,133 , see Fig.…”

Pulse compression of white-light continuum generated at 1053 nm in bulk sapphire: an experimental study

“…A study of a white-light continuum in solid media was carried out by using the Ti: sapphire regenerative amplifier, where a power of more than 300 times the sapphire's critical power (3.4 MW) yielded an octave-spanning spectrum from 400 to 1100 nm [5], measured by the spectrometer (Ocean Optics HR2000). The white-light continuum generated in a 10 mm thick bulk sapphire block aligned with the optical C-axis perpendicular to its faces.…”

“…This can be carried out by employing an optical parametric amplifier (OPA), seeded by a white-light continuum idler pulse [1] which should be compressed by appropriate schemes. The white-light continuum in fiber and optical medium is described and characterized by using the different types of cross-correlation frequency-resolved optical gating techniques [2][3][4][5]. The white-light continuum in the optical bulk material has the potential to be used as a seed and amplify in the femtosecond noncollinear optical parametric amplifiers [6][7][8][9].…”

Cross-correlation frequency-resolved optical gating of white-light continuum (500–900 nm) generated in bulk media by 1053 nm laser pulses

“…The WLC generation in optical media such as sapphire, fused silica and CaF 2 by employing amplified pulses has been described and characterized by the XFROG technique. Imran et al [20,21] employed XFROG with a crystal-dither method to characterize the WLC generation in a sapphire plate seeded by 1053 nm center wavelength laser pulses [22], but were unable to obtain a well-optimized smoother and symmetric region of the WLC spectrum. In the present article, a smoother and symmetric WLC was generated in 10 mm thick sapphire using a color glass filter FGS-900 (Thorlabs, Inc.).…”

“…The filter efficiently suppressed the spectral components below 500 nm and above 900 nm including the residual peak at 1053 nm. The multi-shot SFG-XFROG technique with the crystal-dithering method was employed to overcome the angular limitations of phase matching of the nonlinear crystal [20,21,23,24]. The experimental XFROG traces provide us with a time-frequency distribution, which characterizes the WLC generation in temporal and spectral domains.…”