We report on a polarization-maintaining (PM) very large mode area (VLMA) Er-doped fiber with a 40 µm hexagonal core, fabricated via the REPUSIL powder process. The fiber's performance was evaluated in a MOPA configuration under 976 nm cladding-pumping and 1480 nm core-pumping. A numerical model, distinguishing between isolated ions and clusters to account for cooperative up-conversion and pair-induced quenching, shows excellent agreement with experimental results. This validated model provides a robust tool for designing high-energy, eye-safe PM-VLMA fiber amplifiers.

In this paper we present an alexandrite (Cr3+:BeAl2O4) multipass amplifier pumped by blue LEDs via a luminescent concentrator (LC). This emerging pump technology provides up to 2.6 kW optical pump power during 400 µs at 10 Hz in the 530-630 nm range for low cost, simple and robust implementation. We achieve a single-pass gain of 1.38, the highest ever reported in alexandrite for a semiconductor-based pump source, and a total gain of 34 after 16 passes. The amplifier is injected by a single-frequency laser operating in a quasi-continuous wave at 761 nm. It delivers µs pulses with a peak power of 14 W. This power could significantly improve penetration depth for in vivo acousto-optic imaging.

In this paper, we present a method based on a modal decomposition to quantify the efficiency of photonic lanterns (PLs) based free space optical (FSO) communication receivers. We fabricate a seven-port PL, and we evaluate numerically the free space to fiber coupling efficiency based on a reconstruction of the fields at the PL FSO multimode port. We validate the numerical approach with an experimental characterization of the PL. Then we compare the PL to a commercial multiplane light converter spatial demultiplexer. The PL shows better coupling efficiency for low-order spatial modes with orders of magnitude of demultiplexer size reduction. Finally, we evaluate the PL receiver with a simulation of received optical wavefront in a FSO communication.

In this paper, we present a novel method, to the best of our knowledge, for achieving high-power second-harmonic generation (SHG) of continuous-wave light. By employing lithium triborate-based resonant cavity with moderate finesse, we propose an approach for generating efficient SHG in the visible and ultraviolet spectral ranges without requiring an active electronic servo loop. As a proof of concept, we demonstrate frequency doubling of a high-power 1064 nm laser to 532 nm. To the best of our knowledge, this is the first implementation of such a cavity featuring a highly reflective coating on one end of this crystal. This quasi-monolithic design enables simultaneous control of phase matching and cavity resonance solely through temperature adjustment of the nonlinear crystal.

Quantum technologies promise to utilize the fundamental principles of quantum mechanics to deliver unparalleled possibilities for enhanced data security through quantum cryptography [1], increased computational power via quantum computing [2], and ultra-precise measurement with quantum sensing [3]. Among these complex quantum physics-based systems, alkali atom-based ones are nowadays considered as the most mature platform, bridging the gap to industry in the three pre-cited quantum technology pillars. A new paradigm of these systems can be achieved through geometries (alkali-vapor filled cells, fibers or capillaries) that allow atom/photon interaction in forced transverse geometries by confining the atoms and the optical mode in a waveguide and this potentially over centimeters in length. Applications of these confined vapor sealed are various and comprise (not extensively) quantum spectroscopy [4], electromagnetic field measurement [5], or even refrigeration [6]. Anyway, for obvious reasons of engineering capabilities and intrinsic complexity of these quantum systems these has been up to now reserved to a few academic proof of principle.

Using femtosecond laser pulses, a highly reflective Fiber Bragg Grating was inscribed inside the core of an active PM fiber, integrated into a 1535 nm all-fiber PM laser system.

In this communication, we report for the first time on a homemade 55 µm core VLMA "Yb-free" Er-doped aluminosilicate double-clad fiber manufactured by the REPUSIL powder sintering technology and its implementation within two different laser configurations emitting around 1560 nm, both pumped at 976 nm. First, a free-running free-space CW oscillator delivers up to 40 W of average power with optical-to-optical efficiency of 30 % and near-diffraction-limited beam, despite the large core size. In a second experiment, the fiber is used as the main amplifier of a MOPA system delivering up to 10 nJ pulses at GHz repetition rate.

Recently, quantum technology has gained a lot of interest knowing that this field is expected to provide new opportunities, especially regarding high sensitivity and precision in sensing applications. However, despite the efforts, most quantum sensors are still bulky and hardly operate outside a dedicated environment. In this paper, we present a new approach and the first step in paving the way for an all-fibered cell for alkali atom cooling aiming toward miniaturization of the quantum sensors. The fibered cell consists of a hollow-core photonic crystal fiber (HCPCF) based on a Kagome-Tubular Hybrid cladding [1] placed between two solid Polarizing Maintaining (PM) fibers with high reflection Fiber Bragg Gratings (FBGs) forming a Fabry-Perot (FP) cavity.

Based on the development of a µJ-class Thulium-doped fiber laser operating in the picosecond regime at 1970-nm wavelength, we introduce a solution for three-dimensional (3D) laser writing technologies inside silicon (Si). We reveal that the nonlinear effects preventing from bulk modification in Si with femtosecond pulses persist in the picosecond regime. However, these are strongly reduced which makes possible to derive conditions for a demonstration of data inscription and reading deep into a Si wafer.

We report emission spectrum measurements on single YxEu(1-x)VO4 nanoparticles. The inhomogeneous widths of the emission peaks are identical for single nanoparticles and for ensembles of nanoparticles, while being broader than those of the bulk material. This indicates that individual nanoparticles are identical in terms of the distribution of different local Eu3+ sites due to crystalline defects and confirms their usability as identical, single-particle oxidant biosensors. Moreover, we report a 465 nm solid-state laser based on sum-frequency mixing that provides a compact, efficient solution for direct Eu3+ excitation of these nanoparticles. Both these two aspects should broaden the scope of Eu-doped nanoparticle applications.

We have recently developed an industrial laser platform emitting in the non-conventional range around 976 nm. This 15 W continuous wave spatially single mode linearly polarized fiber laser can be forced to work in narrow line width or single frequency configuration. Its frequency doubling at 488 nm can be used to replace argon gas laser technology in many applications. We have studied the second harmonic generation of our source to verify its suitability with several industrial application needs in terms of efficiency, temporal stability and noise level.

We report the first demonstration of true three level laser emission in diode-pumped Nd doped vanadate and YAG crystals. Wavelengths ranging from 900 to 869 nm open new doors to deeper blue emissions by SHG

We present the first demonstration of Nd:YVO4 laser diode-pumped directly in band at 914-nm. We achieved a slope efficiency of 80.7 % by extracting 11.5W at 1064-nm for 14.6W of absorbed pump power at 914-nm.

We demonstrated for the first time three-level operation at 981 nm with a Yb:KYW crystal inserted into the cavity of a diode pumped Nd:YVO4 laser operating at 914 nm. We achieved an output power up to 1.4 W at 981 nm. Moreover we demonstrated that crystal heating favored laser emission at 981 nm rather than emission at higher wavelength.

Le remplacement des lasers a gaz emettant a 488 nm ou a 442 nm, a l'aide de lasers solides, represente un veritable enjeu industriel. De nombreuses solutions ont ete developpees, neanmoins, celle consistant en le doublement de frequence d'une oscillation autour de 884 nm (cristaux dopes aux ions Nd3+) ou de 976 nm (cristaux dopes aux ions Yb3+) a toujours ete ecartee, de par la nature a trois niveaux des transitions mises en jeu. La tres forte reabsorption du milieu a la longueur d'onde laser rend, a premiere vue, cette alternative peu efficace. Grâce a la significative amelioration de la luminance des diodes de pompe, ce probleme peut desormais etre depasse et l'oscillation de ces transitions envisagee. Dans ces travaux, nous proposons une etude theorique et experimentale de l'oscillation laser en pompage par diode des transitions a trois niveaux dans les cristaux dopes aux ions Nd3+ et Yb3+. Tout d'abord nous presentons l'etude du pompage direct par diode d'un cristal de Nd:GdVO4 emettant a 880 nm, qui apres doublement de frequence nous permet de proposer une alternative aux lasers a HeCd. Nous presentons ensuite un nouveau concept, le pompage en intracavite, que nous appliquons aux cristaux dopes aux ions Yb3+ pour obtenir un effet laser autour de 980 nm. En effet, a l'interieur d'une cavite laser, la forte puissance circulante est couplee a une bonne qualite spatiale de faisceau; ces caracteristiques representent les conditions optimales de pompage d'une transition a trois niveaux. En conclusion, nous proposons une comparaison theorique des differents types de pompage proposes, permettant de degager avantages et inconvenients de chacune de ces deux configurations.

A Nd:YVO4 crystal was pumped directly into the emitting level by a laser diode at 914 nm for the first time to our knowledge. We achieved an output power of 11.5 W at 1064 nm for an absorbed pump power of 14.6 W, corresponding to an optical efficiency of 78.7%. We demonstrated that thermal effects are very weak, in agreement with the low quantum defect of only 14.1%.