Olivier Vanvincq

White-light cw-pumped supercontinuum generation in highly GeO 2 -doped-core photonic crystal fibers

GeO(2)-doped-core photonic crystal fibers show greatly enhanced Kerr and Raman responses with respect to pure silica without any significant modification of the group-velocity dispersion curve. We show that such fibers allow a significant improvement of cw-pumped supercontinuum generation. We report for the first time to our knowledge the generation of a white-light cw-pumped supercontinuum spanning from 470 nm to more than 1750 nm.

Control of supercontinuum generation and soliton self-frequency shift in solid-core photonic bandgap fibers

We experimentally investigate the nonlinear propagation of subnanosecond pulses in solid-core photonic bandgap fibers. By launching pulses with a few kilowatts peak power, a flat supercontinuum is generated. The long-wavelength edge of the supercontinuum can be controlled thanks to the original linear properties inherent to solid-core photonic bandgap fibers. This allows one to tailor the generated supercontinuum radiation and to keep it over a given spectral range of interest without any significant power loss.

Control of the soliton self-frequency shift dynamics using topographic optical fibers

We demonstrate that the dynamics of the soliton self-frequency shift can be accurately controlled by using tapered optical fibers with optimized longitudinal profile shape (that we term topographic fibers). The tapering profiles tailored for a targeted soliton spectral trajectory through dispersion and nonlinearity management are determined by an inverse algorithm. This control is demonstrated experimentally with topographic photonic crystal fibers fabricated directly on a drawing tower.

Significant reduction of power fluctuations at the long-wavelength edge of a supercontinuum generated in solid-core photonic bandgap fibers

We show that the infrared edge of supercontinua generated in solid core photonic bandgap fibers is characterized by a very different temporal behavior than the one obtained in standard fibers. In particular, pulse-to-pulse spectral power fluctuations are significantly reduced near the bandgap edge, and the statistical distribution is quasi-gaussian. The spectral dynamics of this process and statistical properties are investigated experimentally and confirmed by numerical simulations. The reduction of power fluctuations originates from the cancellation of the soliton self-frequency shift near the bandgap edge.

Efficient fiber Bragg gratings in 2D all-solid photonic bandgap fiber.

Fiber Bragg Gratings with reflectivity up to 25 dB have been photo-written in the core of a 2D all-solid Photonic Bandgap Fiber without modification of the guiding properties of the fiber. This result is obtained by combining an appropriate glass composition for the high index inclusions constituting the micro-structured cladding and a photosensitive low index core. Couplings of the fundamental core guided mode with cladding modes are investigated and compared to theoretical predictions.

Ultrabroadband fiber optical parametric amplifiers pumped by chirped pulses. Part 1: analytical model

An analytical model has been developed to fully understand the concept of fiber optical parametric amplifiers pumped by broadband chirped pulses. Our model is in good agreement with the numerical resolution of the nonlinear Schrodinger equation and was used to tailor the gain bandwidth. In particular, we showed that the group delay difference between the pump and the signal can play a crucial role in the spectral extension of the gain. This exciting amplification concept should pave the way toward high gain ultrashort (<30  fs) pulse amplification in fiber.

Fiber-based ultrashort pulse delivery for nonlinear imaging using high-energy solitons

We present an approach for fiber delivery of femtosecond pulses relying on pulse breakup and soliton self-frequency shift in a custom-made solid-core photonic bandgap fiber. In this scheme, the fiber properties themselves ensure that a powerful Fourier-transform-limited pulse is emitted at the fiber output, hence doing away with the need for complex precompensation and enabling tunability of the excitation. We report high-energy soliton excitation for two-photon fluorescence microspectroscopy over a 100-nm range and multimodal nonlinear imaging on biological samples.

Design and realization of flexible very large mode area pixelated Bragg fibers

A new Pixelated Bragg Fiber design showing improved optical performances in terms of single-mode behavior and effective area is presented. The cladding is made of 3 rings of cylindrical high refractive index rods (pixels) in which some pixels are removed to act as a modal sieve for an improved rejection of Higher Order Modes (HOMs). Two half-wave-stack conditions are used to increase the confinement losses of the 3 first HOMs: LP11 and LP02-LP21 guided core modes. The realized fiber exhibits a core diameter of 48.5 μm with an effective single-mode behavior observed from 1000 nm to beyond 1700 nm even for a 1-m-long straight fiber. Losses prove to be low with a minimum value of 25  dB/km between 1200 and 1500 nm. Bending radius of 22.5 cm is reported for this structure without any significant extra-losses above a wavelength of 1350 nm.

Extreme large mode area in single-mode pixelated Bragg fiber

This paper reports the design and the fabrication of an all-solid photonic bandgap fiber with core diameter larger than 100 µm, a record effective mode area of about 3700 µm2 at 1035 nm and robust single-mode behavior on propagation length as short as 90 cm. These properties are obtained by using a pixelated Bragg fiber geometry together with an heterostructuration of the cladding and the appropriated generalized half wave stack condition applied to the first three higher order modes. We detail the numerical study that permitted to select the most efficient cladding geometry and present the experimental results that validate our approach.

Ultrabroadband fiber optical parametric amplifier pumped by chirped pulses. Part 2: sub-30-fs pulse amplification at high gain

We report numerical investigations on ultrashort pulse amplification with high gain in a fiber-based optical parametric amplifier pumped by a broadband chirped pulse. The amplifier has been tailored for ultrabroadband amplification with an analytical model and has key features to overcome gain narrowing and pulse distortion, which are usually observed in ion-doped fiber amplifiers. By combining chirped pump and signal pulses in a fiber, we highlight the possibility to amplify sub-30-fs pulses with standard ultrafast technologies.