Multiphysics model of liquid-cooled Nd:phosphate split-slabs in large aperture optical amplifiers.

High repetition rates in high energy solid-state laser systems can yield to a rise of temperature in amplifiers despite the use of cooling systems. This effect can significantly impact the performance of amplifiers by inducing thermal stress, birefringence or thermal lensing. Here, we develop a multiphysics model to support the design, optimization and commissioning of a liquid-cooled large aperture split-slab laser glass amplifier. This multiphysics model includes optical pumping in the amplifying medium, heat loading, hydraulic effects induced by the liquid coolant, mechanical deformation and their potential coupled effects on the optical wavefront. The accuracy of each model is assessed by carrying out specific experimental measurements and characterizations. We show that this set of models allows the prediction of performance of a liquid-cooled amplifier from the flash-lamp emission to the amplified wavefront at a repetition rate of one shot per minute.

Modeling of the petawatt PETAL laser chain using Miró code.

Miró software has been used intensively to simulate the Laser Megajoule (LMJ) with the treatment of amplification, frequency conversion, and both temporal/spatial smoothing of the beam for nanosecond pulses. We show that the software is able to model most relevant aspects of the petawatt PETAL laser chain in the subpicosecond regime, from the front-end to the focal spot with a broadband treatment of the amplification and compression stages, including chromatism compensation in the laser chain, segmentation and recombination of the beams on the second compression stage, and focusing by an off-axis parabola.

How France launched its donation after cardiac death program.

On the basis of the literature and results presented at the 6th International Conference, donation after cardio-circulatory death provides a significant, practical, additional high quality source of transplantable organs. The vast majority of DCD are 'controlled' Maastricht category III donors. In 2010, the parliamentary information mission on the revision of the bioethics laws invited the Intensive Care Societies to debate and to make recommendations to implement controlled donation after circulatory death. They came to the conclusion that such retrieval is possible in France and insisted on the medical criteria that frame it: the writing of the medical procedures, the ethical aspects and the delay. The major recommendations of the ethics committees were firstly, The WLST decision is independent of the possibility of organ donation; secondly, the strict respect of "The dead donor and organ transplantation rule" and the updated national guidance for the WLST; thirdly, the drafting of a nationally agreed protocol defining the mandatory conditions to determine death and to perform procurement and transplantation. Organ donation after WLST will be authorised only in pilot centres with a locally agreed WLST policy including external second opinion and written transcript of the WLST decision, experienced intensive care staff, a local organ procurement coordination team familiar with DBD and DCD protocols and only in hospitals authorised for organ procurement. It is important to have an optimal and standardized national guidance to limit the known risk factors of graft failure (donor and recipient choice, warm and cold ischemia time), to increase acceptance by medical community and civil society and to improve results and allow more powerful analysis.

Wide-field optical coherence tomography: imaging of biological tissues.

We describe a two-dimensional optical coherence tomography technique with which we were able to obtain multiple longitudinal slices of a biological sample directly in a single Z scan. The system is based on a femtosecond Cr4+:forsterite laser and an infrared camera for wide-field imaging of the sample with a depth resolution of 5 microm. With this imaging apparatus we were able to investigate human skin and mouse ear samples and to observe the different constitutive tissues.

Longitudinal imaging in biological tissues with a single laser shot correlation system.

We demonstrate the potential of a new optical imaging system to directly obtain a longitudinal slice of a biological sample. The system, based on a single-shot optical correlator, operates a time-to-space conversion and an optical time-gating by sum-frequency generation in a nonlinear crystal. Owing to the high speed acquisition of the technique, internal structures of in-vivo tissues can be imaged at video rate.With this apparatus, we recorded longitudinal images of ex vivo mouse ear and in vivo human skin with a depth resolution of approximately 15 microm.

Real-time two-dimensional imaging in scattering media by use of a femtosecond Cr(4+):forsterite laser.

An original femtosecond Cr(4+):forsterite laser source associated with a nonlinear optical correlator was used for imaging through scattering media with 1220-nm light. The system, which operates as an ultrafast optical gate by sum-frequency generation in a nonlinear crystal, was able to detect the light reflected from a resolution chart hidden in a turbid medium, at an attenuation of as much as 15 mean free paths. When the object was illuminated with a collimated beam, real-time two-dimensional images were obtained, with a maximum transverse resolution of ~20 microm.