Yves Coello

Pulse shaping of octave spanning femtosecond laser pulses

Phase characterization, correction and shaping of an ultra-broad-bandwidth femtosecond laser were achieved using a grating-based pulse shaper. By using MIIPS, the compensated pulses generated a second harmonic spectrum spanning over 12,260 cm-1.

Direct measurement of spectral phase for ultrashort laser pulses

We present an intuitive pulse characterization method that provides an accurate and direct measurement of the spectral phase of ultrashort laser pulses. The method requires the successive imposition of a set of quadratic spectral phase functions on the pulses while recording the corresponding nonlinear spectra. The second-derivative of the unknown spectral phase can be directly visualized and extracted from the experimental 2D contour plot, without any inversion algorithm or mathematical manipulation.

Atmospheric pressure femtosecond laser imaging mass spectrometry.

We present a novel imaging mass spectrometry technique using femtosecond laser pulses to ionize the sample at atmospheric pressure and without the need of a laser-absorbing matrix. A 10µm-resolution image of biological tissue is demonstrated.

Group-velocity dispersion measurements of water, seawater, and ocular components using multiphoton intrapulse interference phase scan.

The use of femtosecond lasers requires accurate measurements of the dispersive properties of media. Here we measure the second- and third-order dispersion of water, seawater, and ocular components in the range of 660-930 nm using a new method known as multiphoton intrapulse interference phase scan. Our direct dispersion measurements of water have the highest precision and accuracy to date. We found that the dispersion for seawater increases proportionally to the concentration of salt. The dispersion of the vitreous humor was found to be close to that of water. The chromatic dispersion of the cornea-lens complex was measured to obtain the full dispersive properties of the eye.

Atmospheric pressure femtosecond laser imaging mass spectrometry

We present a novel imaging mass spectrometry technique using femtosecond laser pulses to ablate and ionize the sample at ambient conditions with improved lateral resolution (1μm), as demonstrated here with an image of vegetable cells.

Two-photon fluorescence excitation spectroscopy by pulse shaping ultrabroad-bandwidth femtosecond laser pulses

A fast and automated approach to measuring two-photon fluorescence excitation (TPE) spectra of fluorophores with high resolution (~2 nm) by pulse shaping ultrabroad-bandwidth femtosecond laser pulses is demonstrated. Selective excitation in the range of 675-990 nm was achieved by imposing a series of specially designed phase and amplitude masks on the excitation pulses using a pulse shaper. The method eliminates the need for laser tuning and is, thus, suitable for non-laser-expert use. The TPE spectrum of Fluorescein was compared with independent measurements and the spectra of the pH-sensitive dye 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) in acidic and basic environments were measured for the first time using this approach.

Broadband 2.12 GHz Ti:sapphire laser compressed to 5.9 femtoseconds using MIIPS

We report a self-starting prismless femtosecond Ti:sapphire ring laser whose repetition rate has been gradually increased from 1 to 2.12 GHz. A broadband spectrum extending from 650 to 1040 nm, in which 17% of the intracavity power is generated in a single-pass through the crystal, is preserved in spite of the reduction in peak power. An average power of 0.95 W was obtained for 7.5 W of pump power, with very stable operation verified over 22 hours. Pulses from this laser have been fully characterized in spectral phase, and then compressed to 5.9 femtoseconds using multiphoton intrapulse interference phase scan (MIIPS).

Asynchronous encrypted information transmission with sub-6 fs laser system at 2.12 GHz repetition rate

The asynchronous transmission (encoding and decoding) of 64-bit information using binary spectral phase shaping is demonstrated. The accurate introduction and retrieval of the binary information is possible by using multiphoton intrapulse interference phase scan (MIIPS) to measure and correct the spectral phase distortions of the laser and the transmission media. Experimental demonstration is achieved using a sub-6 fs Ti:Sapphire laser with 2.12-GHz repetition rate and an adaptive phase control system.

Direct Measurement of Spectral Phase for Ultrashort Laser Pulses Based on Intrapulse Interference

We present a method for the direct spectral phase measurement of ultrafast laser pulses. The second-derivative of the unknown spectral phase is revealed by the experimental 2D-contour plot and can be measured without mathematical manipulation.

Direct measurement of spectral phase for ultrafast laser pulses based on multi-photon intrapulse interference

We present a direct measurement method of the spectral phase of ultrafast laser pulses. The second-derivative of the unknown spectral phase can be directly envisioned and extracted from the experimental 2D-contour plot without mathematical manipulation.