Frequency doubled sub 50 fs Erbium-fiber lasers are ideal tool used to seed Ti:sapphire amplifier. Therefore, over last decade large number of all-fiber laser architecture has been reported for such application. Nevertheless, the emitted pulses are usually too long due to the gain bandwidth of Erbium or the laser architecture is not made with Polarization Maintaining (PM) fibers which will be a limitation for frequency doubling. We demonstrate a new design of an all-PM erbium doped fiber laser emitting sub 50 fs pulses with high pulse energy and we study its frequency doubling. Our architecture is based on a concatenation of three amplifiers having different group velocity dispersion. These amplifiers provide numerous degrees of freedom allowing to control the output pulse duration. Thanks to this new design, the laser produces 14 nJ pulse with a duration of 48 fs and an average power of 560 mW. This is to the best of our knowledge the shortest pulse duration with an energy higher than 10 nJ emitted by an all-fiber laser around 1.5-1.6 μm. The pulses are further converted by Second Harmonic Generation to 796 nm with an efficiency of 25 %. The average power of the doubled signal is 140 mW with 3.5 nJ pulse energy. The nonlinear crystal has been carefully chosen in order to cover all the spectral bandwidth of the pump and to ensure a sub 50 fs pulse at 796 nm.
We report on a 3 W Mid-IR supercontinuum extended up to 4.6 μm based on an all-PM thulium doped fiber gainswitched laser seeding an InF<sub>3</sub> fiber. This innovative fiber presents a specific design that increases non-linear effects and shows very weak background losses. Thanks to the versatility of our gain-switched laser, all the pulse parameters have been widely optimized to generate a supercontinuum emission with the highest average power and the largest spectrum.
High power single frequency lasers are very attractive for a wide range of applications such as nonlinear conversion, gravitational wave sensing or atom trapping. Power scaling in single frequency regime is a challenging domain of research. In fact, nonlinear effect as stimulated Brillouin scattering (SBS) is the primary power limitation in single frequency amplifiers. To mitigate SBS, different well-known techniques has been improved. These techniques allow generation of several hundred of watts . Large mode area (LMA) fibers, transverse acoustically tailored fibers , coherent beam combining and also tapered fiber  seem to be serious candidates to continue the power scaling. We have demonstrated the generation of stable 200W output power with nearly diffraction limited output, and narrow linewidth (Δν<30kHz) by using a tapered Yb-doped fiber which allow an adiabatic transition from a small purely single mode input to a large core output.
We report on the design and the fabrication of a new design of an all-solid Bragg fiber based on the pixelization and heterostructuration of a cladding made of only two high index rings. The thickness of the low index ring as well as the geometry of the heterostructuration (its symmetry and the number of removed pixels) have been chosen to maximize the confinement losses of the Higher Order Modes (HOM) (above 10 dB/m) while keeping the Fundamental Mode (FM) losses low (below 0.1 dB/m). The proposed geometry allows having access to different Mode Field Diameter (MFD) from 54 μm to 60 μm at 1 μm wavelength by drawing the same stack to different fiber (and hence, core) diameters. As a result, a record MFD of 60 μm is reported for a Solid Core Photonic Bandgap Fiber (SC-PBGF) and single-mode behavior is obtained experimentally even for a short fiber length (few tens centimeters) maintained straight.