[Industrial property and basic research in the genesis of the mRNA vaccine against COVID-19]. / Propriété industrielle et recherche fondamentale dans la genèse du vaccin ARNm contre la COVID-19.

The extreme speed of the design and provisional approval of the covid-19 mRNA vaccines, as well as the speed of their mass production one year after the start of the pandemic, surprised and contradicted all the experts and big pharmaceutical companies who expected years of development. Their superior efficacy to other vaccines should make mRNA vaccines indispensable, but their diffusion remains low outside developed countries. Several reasons are given, ranging from logistical difficulties to mistrust of populations or the impossibility of producing them locally without lifting patents. Considering that, in these debates, these patents may be challenged because they do not meet the necessary criteria of inventiveness, it appeared necessary to review the history, over more than three decades, of the academic research and entrepreneurial spirit that led to the advent of mRNA platforms, to examine their mutual merits and the role of industrial property for biotechnology companies.

Nd:glass diode-pumped regenerative amplifier, multimillijoule short-pulse chirped-pulse-amplifier laser.

We have built a diode-pumped Nd:glass regenerative amplifier that is able to produce energies up to 20 mJ within a 470-fs pulse duration at a 1-Hz repetition rate. We obtained this amplifier by using specific intracavity components such as a phase mirror and a birefringent filter to generate a large spatial mode and a large spectral width.

Beam-focus shaping by use of programmable phase-only filters: application to an ultralong focal line.

We have developed a high-resolution programmable adaptive-optic device based on an optically addressed liquid-crystal electro-optic valve controlled by an achromatic three-wave lateral shearing interferometer. We apply this phase-only filter and loop to shape the far-field pattern of laser beams. As a first application, we theoretically compute and experimentally verify the focus along a line longer than tens of Rayleigh ranges.

All-optical programmable shaping of narrow-band nanosecond pulses with picosecond accuracy by use of adapted chirps and quadratic nonlinearities.

We experimentally demonstrate pure optical pulse picosecond shaping of narrow-bandwidth nanosecond pulses. The method used is based on the manipulation in the spectral domain of strongly chirped femtosecond pulses and on the use of either frequency addition or frequency difference.

Photometric observations of a polychromatic laser guide star.

We report the photometric observation of a polychromatic laser guide star (PLGS) using the AVLIS laser at the Lawrence Livermore National Laboratory (LLNL). The process aims at providing a measurement of the tilt of the incoming wave front at a telescope induced by atmospheric turbulence. It relies on the two-photon coherent excitation of the 4D5/2 energy level of sodium atoms in the mesosphere. We used two laser beams at 589 and 569 nm, with a maximum total average output power of approximately 350 W. For the purpose of photometric calibration, a natural star was observed simultaneously through the same instrument as the PLGS at the focus of the LLNL 50-cm telescope. Photometric measurements of the 330-nm return flux confirm our previous theoretical studies that the PLGS process should allow us at a later stage to correct for the tilt at wavelengths as short as approximately 1 microm at good astronomical sites. They show also that, at saturation of two-photon coherent absorption in the mesosphere, the backscattered flux increases by a factor of approximately 2 when the pulse repetition rate decreases by a factor of 3 at constant average power. This unexpected behavior is briefly discussed.

Ultrashort, intense ultraviolet pulse generation by efficient frequency tripling and adapted phase matching.

We demonstrate efficient frequency tripling of 1057-chirped pulses, using adapted chirping and thick KDP crystals. These millijoules broadband pulses at 352 nm have been compressed to 220-fs duration by use of a UV grating-pair compressor. The technique is scalable to kilojoule petatwatt lasers.

Nearly diffraction-limited laser focal spot obtained by use of an optically addressed light valve in an adaptive-optics loop.

We demonstrate correction of laser wave-front distortions by use of an adaptive-optical technique based on a light valve. The setup consists of an achromatic and adjustable-sensitivity wave-front sensor and a wave-front corrector relying on an optically addressed liquid-crystal spatial light modulator. Experimental results with strongly aberrated beams focused close to the diffraction limit are presented for the cw regime. Additional experiments with pulses and measurement of damage thresholds show that this approach is relevant for spatial phase correction of ultraintense laser pulses.

Efficient generation of narrow-bandwidth picosecond pulses by frequency doubling of femtosecond chirped pulses.

We demonstrate efficient generation of picosecond narrow-bandwidth pulses by frequency mixing of broadband opposite chirped pulses in a type I doubling crystal. This procedure allows us to produce picosecond pulses that are perfectly synchronized with femtosecond pulses. The experiment shows a decrease of the initial bandwidth by a factor of more than 30, while a high conversion efficiency is maintained.

Femtosecond diffracting Fourier-transform infrared interferometer.

We have developed a new scheme of Fourier-transform spectroscopy in the mid and the far infrared. The method relies on an interferometer in the visible or the near infrared, providing a sequence of two femtosecond pulses, which in turn generate a sequence of infrared pulses. The geometrical properties of the different diffracted infrared waves are used to isolate the relevant signal. An experimental demonstration is shown in the mid infrared by use of optical rectification of near-infrared 15-fs pulses.

Nonlinear temporal diffraction and frequency shifts resulting from pulse shaping in chirped-pulse amplification systems.

We present experimental results of the amplification of strongly amplitude-modulated chirped pulses resulting from the coherent addition of two delayed short pulses. The nonlinearities in the amplifier chain induce a temporal diffraction resulting in prepulses and postpulses, in addition to the two main pulses when compressed. Simultaneously, temporal-resolved and spectral-resolved output pulses show that the prepulses and postpulses are blue shifted and red shifted, respectively, explaining the causality of the system.

Compact and efficient multipass Ti:sapphire system for femtosecond chirped-pulse amplification at the terawatt level.

We have developed efficient multipass Ti:sapphire amplifiers for femtosecond chirped-pulse amplification. With only two of these devices we get an amplification factor of 10(8), which corresponds to a peak power of ~0.5 TW after compression. We present a detailed analysis of such a system and its advantages in terms of its high quantum yield (0.3), flexibility, optical quality, and potential for tunability.

Generation of 20-TW pulses of picosecond duration using chirped-pulse amplification in a Nd:glass power chain.

Pulses of 20-TW peak power have been generated at 1064 nm using the chirped-pulse-amplification technique with a 90-mm output-aperture Nd:silicate glass amplification line. This system delivers 60 J of energy in a chirped pulse of 600-psec duration, with a capacity to maintain a 3.5-nm output bandwidth. These chirped pulses are compressed to 1.2 psec with an energy of 24 J by using large holographic gold-coated 1740-lines/mm diffraction gratings.