Direct fiber comb stabilization to a gas-filled hollow-core photonic crystal fiber

We have isolated a single tooth from a fiber laser-based optical frequency comb for nonlinear spectroscopy and thereby directly referenced the comb. An 89 MHz erbium fiber laser frequency comb is directly stabilized to the P(23) (1539.43 nm) overtone transition of [superscript]12C[subscript]2H[subscript]2 inside a hollow-core photonic crystal fiber. To do this, a single comb tooth is isolated and amplified from 20 nW to 40 mW with sufficient fidelity to perform saturated absorption spectroscopy. The fractional stability of the comb, ~7 nm away from the stabilized tooth, is shown to be 6 × 10[superscript]−12 at 100 ms gate time, which is over an order of magnitude better than that of a comb referenced to a GPS-disciplined Rb oscillator

Hypocycloid-shaped hollow-core photonic crystal fiber Part II: Cladding effect on confinement and bend loss

We report on numerical and experimental studies on the influence of cladding ring-number on the confinement and bend loss in hypocycloid-shaped Kagome hollow core photonic crystal fiber. The results show that beyond the second ring, the ring number has a minor effect on confinement loss whereas the bend loss is strongly reduced with the ringnumber increase. Finally, the results show that the increase in the cladding ring-number improves the modal content of the fiber

Hypocycloid-shaped hollow-core photonic crystal fiber Part I: Arc curvature effect on confinement loss

We report on numerical and experimental studies showing the influence of arc curvature on the confinement loss in hypocycloid-core Kagome hollow-core photonic crystal fiber. The results prove that with such a design the optical performances are strongly driven by the contour negative curvature of the core-cladding interface. They show that the increase in arc curvature results in a strong decrease in both the confinement loss and the optical power overlap between the core mode and the silica core-surround, including a modal content approaching true single-mode guidance. Fibers with enhanced negative curvature were then fabricated with a record loss-level of 17 dB/km at 1064 nm

A strong-field driver in the single-cycle regime based on self-compression in a kagome fibre

Over the past decade intense laser fields with a single-cycle duration and even shorter, subcycle multicolour field transients have been generated and applied to drive attosecond phenomena in strong-field physics. Because of their extensive bandwidth, single-cycle fields cannot be emitted or amplified by laser sources directly and, as a rule, are produced by external pulse compression—a combination of nonlinear optical spectral broadening followed up by dispersion compensation. Here we demonstrate a simple robust driver for high-field applications based on this Kagome fibre approach that ensures pulse self-compression down to the ultimate single-cycle limit and provides phase-controlled pulses with up to a 100 μJ energy level, depending on the filling gas, pressure and the waveguide length

Ultra-flat wideband single-pump Raman-enhanced parametric amplification

We experimentally optimize a single pump fiber optical parametric amplifier in terms of gain spectral bandwidth and gain variation (GV). We find that optimal performance is achieved with the pump tuned to the zero-dispersion wavelength of dispersion stable highly nonlinear fiber (HNLF). We demonstrate further improvement of parametric gain bandwidth and GV by decreasing the HNLF length. We discover that Raman and parametric gain spectra produced by the same pump may be merged together to enhance overall gain bandwidth, while keeping GV low. Consequently, we report an ultra-flat gain of 9.6±0.5 dB over a range of 111 nm (12.8 THz) on one side of the pump. Additionally, we demonstrate amplification of a 60 Gbit/s QPSK signal tuned over a portion of the available bandwidth with OSNR penalty less than 1 dB for Q2 below 14 dB

Tunable ultra-fast infrared generation in a gas-filled hollow core capillary by a four-wave mixing process: erratum

This erratum reports corrections to the temporal axes in Figs. 12 and 13 of J. Opt. Soc. Am. B 39, 662 (2022)JOBPDE0740-322410.1364/JOSAB.444574

Hollow-core Optical Fiber Gas Lasers (HOFGLAS): a review [Invited]

International audienceThe development of hollow core photonic crystal fibers with low losses over a broad spectral region in the near IR enabled the demonstration of a novel laser type - Hollow-core Optical Fiber Gas Laser (HOFGLAS). The laser combines attractive features of fiber lasers such as compactness and long interaction length of pump and laser radiation with those of gas lasers such as the potential for high output power and narrow line width. This paper summarizes recent developments and describes the demonstration of C2H2 and HCN prototype lasers. Avenues to extend laser emission further into the IR are discussed

Spectroscopie linéaire et non-linéaire de polymères conducteurs dans le domaine térahertz

This thesis project aims to study transport mechanisms in conducting polymers PEDOT/PSS and PEDOT/PSTFSIK in the terahertz (THz) domain. These two polymers come from LCPO laboratory.First of all, we studied intrinsics properties of these materials in the THz domain with a THz-TDS experiment. This drove us to show that their transmission is quasi-constant in the THz domain and that the intrinsic conductivity is larger for PEDOT/PSS than PEDOT/PSTFSIK. This last result has been obtained by using two differents fitting models of conduction. The first model, so-called Drude-Smith model, extend the Drude model by adding a trap parameter. It also possess only few fitting parameters. The second one, the Dyre model, take into account of the grain structure of polymers. Nevertheless, it has several fitting parameters. We obtained a direct current conductivity of polymers that is in excellent agreement with LCPO measurements.Among these, we caracterized the behavior of PEDOT/PSS and PEDOT/PSTFSIK under a femtosecond pulse centered in the bipolaronic band. We also have the THz pulse. By using Drude-Smith and Dyre models, we were able to study the change of conductivity induced by the femtosecond pulse in the THz domain. In this case, we supposed that fitting parameters have to be a function of the delay between the femtosecond pulse and the THz pulse.Finally, by studying PEDOT/PSS and PEDOT/PSTFSIK responses for differents pump intensity in a full optic experiment, where we pumped on the bipolaronic band and probed on the polaronic band, we were be able to give a possible scenario for the impact of the optical pump in these materials.Ces travaux de thèse portent sur l'étude des mécanismes de transport de charges au sein des polymères conducteurs PEDOT/PSS et PEDOT/PSTFSIK dans le domaine térahertz (THz). Ces polymères conducteurs viennent du LCPO.En premier lieu, nous avons étudié les propriétés intrinsèques de ces matériaux dans le domaine THz à partir d'une expérience de spectroscopie THz-TDS. Ceci a permis d'une part de montrer que la transmission des deux polymères est quasi-constante sur la plage de fréquences considérées et d'autre part que la conductivité intrinsèque du PEDOT/PSS est plus importante que celle du PEDOT/PSTFSIK. Ce dernier résultat a été obtenu en ajustant les données de conductivité par deux modèles de conduction bien distincts. Le premier est le modèle de Drude-Smith qui étend le modèle de Drude par l'ajout d'un coefficient de piégeage, il ne possède que peu de paramètres ajustables. Le second, le modèle de Dyre, permet de prendre en compte la structure en grains des polymères conducteurs. Il possède néanmoins un grand nombre de paramètres ajustables. Les mesures de conductivité en régime continu obtenues à partir des modèles sont en accord avec les mesures effectuées au LCPO.Nous avons ensuite caractérisé le comportement des polymères conducteurs PEDOT/PSS et PEDOT/PSTFSIK soumis à une impulsion femtoseconde centrée dans la bande bipolaronique de ces matériaux en plus de l'impulsion THz déjà présente. En utilisant les modèles de Drude-Smith et de Dyre, nous avons pu étudier le changement de conductivité induit par l'impulsion femtoseconde dans le domaine THz en supposant que les paramètres ajustables des modèles dépendent maintenant du délai entre l'impulsion femtoseconde et l'impulsion THz.Finalement, en étudiant les réponses du PEDOT/PSS et du PEDOT/PSTFSIK pour différentes intensités de pompe dans le cadre d'une expérience tout-optique où à on a pompé dans la bande bipolaronique et où on a sondé dans la bande polaronique des polymères conducteurs, on a pu échafauder un scénario plausible pour l'impact de la pompe optique dans ces matériaux