Antoine Courjaud

On Yb:CaF2 and Yb:SrF2 : Review of spectroscopic and thermal properties and their impact on femtosecond and high power laser performance

We present an overview of laser results we obtained with Yb-doped calcium fluoride and its isotype strontium fluoride. In order to study the laser performance in femtosecond and high power regimes, spectral and thermal properties are first discussed including the potential of these crystals at room and cryogenic temperatures. Experimental demonstrations of high-power and ultrashort pulse oscillators and amplifiers are presented and analyzed.

Ultrashort pulse laser surgery of the cornea and the sclera

The strongly localized interaction process of ultrashort laser pulses with tissue makes femtosecond lasers a powerful tool for eye surgery. These lasers are now routinely used in refractive surgery and other forms of surgery of the anterior segment of the eye. Several clinical laser systems also offer options for corneal grafting and the potential use of ultrashort pulse lasers in glaucoma surgery has been the object of several recent studies which have shown promising results. While devices aimed for interventions in clear tissue may be based on available solid state or fibre laser technology, the development of tools for surgery in more strongly scattering tissue has to account for the compromised tissular transparency and requires the development of optimized laser sources. The present paper focuses on surgery of clear and pathological cornea as well as sclera. It aims to give an overview over typical medical indications for ultrashort pulse laser surgery, the optics of the tissues involved, the available laser technology, the laser–tissue interaction process, and possible future developments.

Highly efficient, high-power, broadly tunable, cryogenically cooled and diode-pumped Yb:CaF2

We present a high-power diode-pumped Yb:CaF(2) laser operating at cryogenic temperature (77 K). A laser output power of 97 W at 1034 nm was extracted for a pump power of 245 W. The corresponding global extraction efficiency (versus absorbed pump power) is 65%. The laser small signal gain was found to be equal to 3.1. The laser wavelength could be tuned between 990 and 1052 nm with peaks that correspond well to the structure of the gain cross-section spectra registered at low temperature.

Short-pulse and high-repetition-rate diode-pumped Yb:CaF2 regenerative amplifier.

We present a diode-pumped regenerative amplifier based on an Yb:CaF(2) crystal optimized to produce short pulses for various repetition rates ranging from 100 Hz to 10 kHz. The shortest pulse duration generated is 178 fs, and the corresponding energy is 1.4 mJ before compression (620 microJ after), at a repetition rate of 500 Hz for 16 W of pump power. The bandwidth is 10 nm centered at 1040 nm. Higher repetition rate regimes have also been explored, allowing an optical-to-optical efficiency up to 10% at a high repetition rate.

High-power diode-pumped cryogenically cooled Yb:CaF2 laser with extremely low quantum defect

High-power diode-pumped laser operation at 992-993 nm under a pumping wavelength of 981 of 986 nm is demonstrated with Yb:CaF₂ operating at cryogenic temperature (77 K), leading to extremely low quantum defects of 1.2% and 0.7%, respectively. An average output power of 33 W has been produced with an optical efficiency of 35%. This represents, to the best of our knowledge, the best laser performance ever obtained at such low quantum defects on intense laser lines.

High-power diode-pumped Yb:KGW ultrafast laser

Summary from only given. We present a simple passively modelocked diode-pumped Yb:KGd(WO/sub 4/)/sub 2/ (Yb:KGW) laser. We achieved pulses as short as 150 fs and an average output power of 1.5 W by using a 15 W fiber-coupled laser diode to pump the laser crystal, and a semiconductor saturable absorber mirror (SESAM) to initiate passive mode locking.

Polarized multiplex coherent anti-Stokes Raman scattering using a picosecond laser and a fiber supercontinuum

We perform multiplex coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy with a picosecond pulsed laser and a broadband supercontinuum (SC) generated in photonic crystal fiber. CARS signal stability is achieved using an active fiber coupler that avoids thermal and mechanical drifts. We obtain multiplex CARS spectra for test liquids in the 600-2000 cm(-1) spectral range. In addition we investigate the polarization dependence of the CARS spectra when rotating the pump beam linear polarization state relative to the linearly polarized broad stokes SC. From these polarization measurements we deduce the Raman depolarization ratio, the resonant versus nonresonant contribution, the Raman resonance frequency, and the linewidth.

Diode pumped multikilohertz femtosecond amplifier

We report on a high-energy diode pumped Yb:KGW femtosecond system delivering 0.2 mJ, 420 fs pulses at repetition rates up to 3 kHz. A single 15 W fiber-coupled diode pumps the amplifier leading to a compact reliable system for industrial applications.

Optimization and characterization of a femtosecond tunable light source based on the soliton self-frequency shift in photonic crystal fiber

We take advantage of the Raman soliton self-frequency shift experienced during the propagation in an anomalous dispersive photonic crystal fiber in order to continuously tune the central frequency of ultrashort pulses. We discuss the fiber properties to be favored to obtain high power spectral densities and we carry out an extensive experimental study of the properties of the frequency shifted pulses in terms of spectral, autocorrelation, and RF spectrum measurements.

1 mJ, multi-kHz, sub-500 fs Diode-pumped Ytterbium Laser Amplifier

We demonstrate a directly diode-pumped Yb:KYW femtosecond laser amplifier with > 1 mJ pulse energy and pulse repetition rates higher than 5 kHz. The pulse duration was 480 fs and the M2 better than 1.2.