Dimitris Papadopoulos

Apollon-10P: Status and implementation

The objective of the Institut de Lumie`re Extreme consists in providing early in 2014 to the international scientific community an unique laser based facility delivering 150 J, 15 fs pulses at 1 shot per minute repetition rate allowing to investigate an unexplored domain of laser-matter interaction at 1023 - 1024 W/cm2 intensity level.

Passive coherent combining of CEP-stable few-cycle pulses from a temporally divided hollow fiber compressor

We demonstrate a robust passive coherent combining technique for post-compression of mJ energy CEP-stable laser pulses down to few-cycle duration in a gas-filled hollow-fiber. High combining efficiency is achieved using carefully oriented calcite plates.

Coherent combination of ultrafast fiber amplifiers

We review recent progress in coherent combining of femtosecond pulses amplified in optical fibers as a way to scale the peak and average power of ultrafast sources. Different methods of achieving coherent pulse addition in space (beam combining) and time (divided pulse amplification) domains are described. These architectures can be widely classified into active methods, where the relative phases between pulses are subject to a servomechanism, and passive methods, where phase matching is inherent to the geometry. Other experiments that combine pulses with different spectral contents, pulses that have been nonlinearly broadened or successive pulses from a mode-locked laser oscillator, are then presented. All these techniques allow access to unprecedented parameter range for fiber ultrafast sources.

High-contrast 10 fs OPCPA-based front end for multi-PW laser chains

Applications using multi-PW lasers necessitate high temporal pulse quality with a tremendous contrast ratio (CR). The first crucial prerequisite to achieve multi-PW peak power is the generation of ultrashort pulses with good spectral phase quality. Second, to avoid any deleterious pre-ionization effect on targets, nanosecond contrast better than 1012 is also targeted. In the framework of the Apollon 10xa0PW French laser program, we present a high-contrast 10xa0fs front-end design study to inject highly energetic Ti:sapphire PW lasers. The CR has been measured and analyzed in different time ranges highlighting the different major contributions for each scale.

Actively Q-Switched Multisegmented Nd:YAG Laser Pumped at 885 nm for Remote Sensing

An end-pumped actively Q-switched Nd:YAG laser using a multisegmented crystal rod as laser active material, directly pumped to the upper laser level by an 885-nm emitting diode is demonstrated. The Nd:YAG crystal was pumped both in CW and quasi-CW mode. The maximum energy per pulse obtained was 2.57 mJ at 1 kHz, with an overall efficiency of ~ 7.5) %. The pulse duration was 22-ns full-width at half-maximum while the spatial beam profile was excellent (M2<;1.3) .

High-fidelity frontend based on XPW filter for high-contrast few-cycle OPCPAs

We demonstrate a 80μJ, 5fs, CEP-stable injector with high spectro-temporal quality. The device relies on post-compression in a hollow-core fiber followed by XPW filtering and is an ideal seed for high-power high-contrast OPCPA systems.