We report the experimental demonstration of a continuous-wave all-fiber optical parametric amplifier in the 1 µm band with a record bandwidth of more than 20 THz and a peak gain of almost 40 dB. This is achieved by using a photonic crystal fiber with a high figure of merit and strongly reduced longitudinal dispersion fluctuations. Due to their unique bandwidth and gain characteristics, fiber parametric amplifiers at 1 µm provide an interesting alternative to solid-state or ytterbium-doped fiber amplifiers for ultrafast optical pulse and signal processing.

The fabrication and characterisation of a highly-nonlinear germanium doped silica based photonic crystal fibre are reported. It exhibits high Kerr and Raman nonlinear coefficients as high as 69.3 W -1 .km -1 and 94 W -1 .km -1 , respectively, with a low attenuation of 17.5 dB/km around 1 m, which leads to a record figure of merit at this wavelength.

We report the fabrication and characterization of photonic crystal fibers having a core doped with 10 wt% of phosphorus and a zero dispersion wavelength (ZDW) around 1 μm. These fibers were successfully used for high-power visible continuous wave (CW) supercontinuum generation with an output average power up to 36 W and spectral power densities of 20 mW/nm at 1550 nm and 2 mW/nm at 650 nm. We also show that the spectral power density in the whole region below the pump wavelength significantly increases as the ZDW moves closer to the pump wavelength, at the expense of the short-wavelength edge that slightly redshifts.

We report recent advances in the domain of Highly Non-Linear Photonic Crystal Fibers (HNL-PCFs) especially designed as gain medium for Raman fiber lasers. Indeed, a fiber Raman coefficient as high as 42 W-1.km-1 at 1.12μm has been obtained, while keeping optical losses moderate, below 6 dB/km at this wavelength. We have calculated that only 2 meters of such a germanium doped HNL-PCF is required to obtain an output power in the order of 10W at 1.12 μm with an efficiency of 90%. Experimental output optical spectra of multi-cascades cavities are finally given.

In this paper, we first show with modelling work that, as is well known for step-index fibers. A hole assisted fiber was designed with this method and fabricated, targeting MAC values around 7.7 with minimum bending loss. Six holes were drilled in a preform made with standard Draka process. The drawing was performed on a standard single mode fiber production tower.

We study guided acoustic wave Brillouin scattering (GAWBS) in several photonic crystal fibers (PCF) with different kind of air-hole microstructure and we show this effect is enhanced only for a few acoustic phonons. The results of our numerical simulations based on a finite element method reveal that these acosuti waves emitted in the GHz range are indeed trapped within the air-hole microstructure, in good agreement with experimental observations. The periodic wavelength-scale air-hole microstructure of solid-core PCFs can indeed drastically alter the transverse elastic waves distribution and therefore forward Brillouin scattering compared to what is commonly observed in conventional all-silica fibers. We show additionnally that the elasto-optic diffraction coefficient and the transverse acousto-optic field overlap are maximum for these acoustic waves. For the most intense GAWBS modes, we investigate the scattering efficiency and temperature dependence of the fundamental phonon frequency for sensing applications.

Writing Bragg gratings inside the core of a photonic crystal fiber (PCF), we demonstrate an all-fiber Raman laser fully made with a highly nonlinear PCF. The laser delivers an Output power of 4 Watt. (C) 2008 Optical Society of America

We demonstrate a Raman laser made from a grating-free highly-nonlinear photonic crystal fiber. The laser threshold power is lower than 600 mW and laser power characteristics recorded in experiments are accurately described from the usual simplest model dealing only with stationary evolutions of total optical polvers.(10) Experimental investigations of the spectral properties of our grating-free Raman fiber laser evidence that the shape of the Stokes power spectrum remains remarkably Gaussian whatever the incident pump power. Increasing the incident pump power induces a drift of the Stokes wavelength together with a broadening of the Stokes optical spectrum. Investigations on the role of light polarization on laser characteristics show that our gratin-free Raman fiber laser behaves as a Raman laser made with a standard polarization maintaining fiber. At high pump power, the birth of the second-order Stokes wave induces a destabilization of the laser output with the emergence of self-oscillations of the optical powers which are explained from the interplay between counterpropagating pump and Stokes waves through stimulated Raman scattering,

We experimentally study a new regime for supercontinuum (SC) generation in the nanosecond pulsed regime using a microstructured optical fiber with two zero-dispersion wavelengths (ZDWs). Pumping at 1535 nm around the second ZDW yields a nearly flat SC over 1350-1700 nm. The interplay between the effects of modulation instability and stimulated Raman scattering are described through simple phase-matching relations.

We demonstrate a Raman laser made from a grating-free highly-nonlinear photonic crystal fiber. The laser threshold power is lower than 600 mW and laser power characteristics recorded in experiments are accurately described from the usual simplest model dealing only with stationary evolutions of total optical powers [J. Opt. Soc. Am. 69, 803-807 (1979)]. In our theoretical treatment, reflectivity coefficients are fixed parameters, in strong contrast with procedures usually implemented to describe Raman fiber lasers made with fiber Bragg gratings. Experimental investigations of the spectral properties of our grating-free Raman fiber laser evidence that the shape of the Stokes power spectrum remains remarkably Gaussian whatever the incident pump power. Increasing the incident pump power induces a drift of the Stokes wavelength together with a broadening of the Stokes optical spectrum. Investigations on the role of light polarization on laser characteristics show that our grating-free Raman fiber laser behaves as a Raman laser made with a standard polarization maintaining fiber.

We present an overview of second harmonic generation in optical fibres and we show some new results regarding this quadratic nonlinear phenomenon generation obtained in doped and undoped microstructured fibres.

We present ArF laser-induced dynamics of Bragg grating (BG) growths in phosphosilicate-doped or germanosilicate-doped core photonic crystal fibers (PCFs). To this end, we have adapted the technique of H2 loading, usually used in conventional fiber, to the case of microstructured fiber, allowing both the concentration of hydrogen in the PCFs to be kept nearly constant for the time of the exposure and the BG spectra to be easily recorded. We compared the characteristics of BG growths in the two types of PCF to those in conventional step-index fibers. We then conducted a study of the thermal stability of the BGs in PCFs through 30 min of isochronal annealing. At the same time we discuss the role played by the microstructuration and the doping with regard to the grating contrast and the Bragg wavelength stability.

We evaluate the trefoil channels present between the holes of microstructured fibers as a potential dense array of small waveguides. In channels with an inner radius of 330nm, calculations indicate possible propagation with a mode waist of ~350nm at lambda=670nm, near to the diffraction limit. Actual measurements have been performed on a 1-meter fiber section, with injection by a microlensed fiber and mapping of output by near-field scanning optical microscopy. They show that light can be output in individual channels or in several of them, depending on the injection. The observed waist is ~500nm, possibly due to experimental widening. Estimated propagation losses are <20dB/m. Since each channel occupies only 2microm2, this structure opens a way to dense parallel optical processing.

We report on the evaluation of a microstructured optical fiber (MOF) designed for non-linear signal processing applications, i.e., with a very small guided mode (waist ∼1 μm). Calculations predict an intrinsic (assuming propagation in the fundamental mode and zero-loss coupling) non-linear γ coefficient of 40 W-1 km-1 at λ=1.55 μm, but they also predict a basic multimode character. NSOM measurements validate directly the high intrinsic γ value (32±10 W-1 km-1) and also show that with an optimized coupling, the overall losses in efficiency taking into account coupling losses and weak excitation of higher-order modes and leaky modes are only 2.5 dB. This performance is adequate for use in all-optical data processing lines, all the more since it is maintained for relevant propagation lengths and peak power densities.