J.-C. Chanteloup

Influence of ASE on the gain distribution in large size, high gain Yb 3+ :YAG slabs

Amplified spontaneous emission (ASE) in large size, high gain Yb(3+):YAG slabs severely impacts the gain/energy storage capability. We will discuss numerical simulations and experimental results obtained on large size Yb(3+):YAG slabs. The spatial distribution and temporal evolution is shown under different conditions.

Overview of the Lucia laser program: toward 100-Joules, nanosecond-pulse, kW averaged power based on ytterbium diode-pumped solid state laser

We present the current status of the Lucia laser being built at the LULI laboratory, the national civil facility for intense laser matter interaction in France. This diode pumped laser will deliver a 100 Joules, 10 ns, 10 Hz pulse train from Yb:YAG using 4400 power diode laser bars. We first focus on the amplifier stage by describing the reasons for selecting our extraction architecture. Thermal issues and solutions for both laser and pumping heads are then described. Finally, we emphasize more specifically the need for long-lifetime high-laser-damage-threshold coatings and optics.

Current status of the LUCIA laser system

The current status of the LUCIA laser program is discussed. While aiming at 100J, 10Hz, 10ns, a first milestone is set at 10 Joules with a repetition rate of 1–3 Hz. 7ns long, sub-mJ pulses generated by a cavity-dumped oscillator are first preamplified at the sub-J level. Thermal effects limit amplification and repetition rate at this stage. These pulses will be injected into the main amplifier, where amplification is limited by amplified spontaneous emission. It is expected that these pulses reach energy level of ~10J.

Wavelength tunable, 264 J laser diode array for 10 Hz/1ms Yb:YAG pumping

The Lucia [1,2] Laser program, under development at the LULI laboratory, aims at delivering a 1030 nm, 100J, 10 Hz, 10 ns pulse train. The two laser heads used in the amplification stage relies on water-cooled mm-thick Yb:YAG disks, each of them pumped by a 34×13 cm2 Laser Diode Array (LDA). For each LDA, the 88 QCW diodes stacks manufactured by DILAS GmbH will be tiled in an 8×11 arrangement. Fine wavelength tuning is performed through bias current adjustment, water temperature control and conductivity adjustment. Wavelength homogeneity experimental verification has been validated.

Overview of the LULI diode-pumped laser chain proposal for HIPER kJ beamlines

A major challenge the HiPER project is facing is to derive laser architectures satisfying simultaneously all HiPER requirements; among them, high wall-plug efficiency (~ 10%) and repetition rate (5 to 10 Hz) are the most challenging constraints. The active mirror Yb:YAG amplifier proposal from LULI is described.

Progress in the LUCIA project

We present in this paper the actual status of the LUCIA project, a high average power diode-pumped solid-state laser chain capable to deliver 100 J in nanosecond regime at 10 Hz. In a first step, we deal with the choice of the amplifier medium and the pump and extraction architecture. We present after the thermal management and the cooling architecture. Then, we investigate the damage threshold required. We present last the performances already obtained and the improvements we are working out.

Amplified spontaneous emission in large size, high gain Yb 3+ :YAG amplifiers: Numerical modeling and experimental test bench for foreseen kJ-range Diode Pumped Solid State Laser facilities

We will present a three-dimensional Monte-Carlo model calculating the impact of amplified spontaneous emission on large size, high gain quasi-three level laser materials, especially Yb3+:YAG and compared it to experimental results, currently under progress.

Diode pumped Yb:YAG V-shape unstable super Gaussian laser resonators for 10 Hz – 100 joules class laser

A diode-pumped Yb:YAG laser has been demonstrated. A V-shape unstable resonator with a Super Gaussian coupling mirror was chosen. We describe the model that permits to choose the parameters of the cavity and predict the laser performances. A diode pumping architecture is used in which 941 nm radiation is homogenously delivered to the laser crystal. We present here the Pumping Delivery Optics and the laser performances.

Highly scalable femtosecond coherent beam combining

Coherent beam combining (CBC) [1] of fiber amplifiers provides an attractive mean of reaching simultaneously the high peak and high average powers required for various industrial, scientific and defense applications. By using this technique, the highest energy provided by an ultrafast fiber laser system was recently established [2]. For much higher energies, architecture has to be compatible with very large number of fibers [3]. Thus, the goal of the XCAN project is to overcome all the key scientific and technological barriers to the design and development of an experimental laser demonstrator with 61 fiber amplifiers coherently combined.

From 10 to 30 joules with the Lucia laser system: Update on current performance and future cryogenic amplifier

10.2 J 7ns pulses were extracted at 2Hz in four passes from Lucia active mirror Yb3+: YAG diode pumped laser amplifier. A second amplifier head relying on cryogenic cooling will allow reaching the 30J level.