Ultra low-loss hypocycloid-core Kagome hollow-core photonic crystal fiber for green spectral-range applications.

We report on the development of a hypocycloidal-core Kagome hollow-core photonic crystal fiber guiding, with low transmission loss in the 450-650 nm visible spectral range. Transmission loss records have been achieved with 70 dB/km at 600 nm, and 130 dB/km at 532 nm. As a demonstration of the fiber potential applications, we report on a compact 600 THz wide Raman comb generator, centered around 532 nm, and on a 10 W average power frequency-doubled Yb-fiber picosecond laser beam delivery, along with its use for organic material laser micro-processing.

High temperature stable PbS quantum dots.

For the fabrication of nanoparticle containing optical fibers by melt and draw technique, nanoparticle stability at high temperatures is a requirement. We report the synthesis of quantum dots at temperatures as high as 1000 °C, compatible with fiber drawing, stabilized for the first time by a prior low temperature heating step. It is observed that quantum dots formed by this two step heating leads to a better emission stability at high powers associated with a reversible phenomenon, making these nanomaterials suitable for further technological applications.

Millijoule laser pulse delivery for spark ignition through kagome hollow-core fiber.

We report on power handling oriented design of kagome lattice hollow-core fiber and demonstrate through it for the first time nanosecond laser pulses induced spark ignition in a friendly manner. Two different core designs and transmission bands are investigated and evaluated. The energy threshold damage was measured to be in excess of the 10 mJ level and the output power density is approaching the TW/cm2 after focusing; demonstrating the outstanding ability of such fiber for high power delivery.

Low-loss singlemode large mode area all-silica photonic bandgap fiber.

We describe the design and characterization of solid core large mode area bandgap fibers exhibiting low propagation loss and low bend loss. The fibers have been prepared by modified chemical vapor deposition process. The bandgap guidance obtained thanks to a 3-bilayer periodic cladding is assisted by a very slight index step (5.10-4) in the solid core. The propagation loss reaches a few dB/km and is found to be close to material loss.

Design of dispersion-compensating fibers based on a dual-concentric-core photonic crystal fiber.

A photonic crystal fiber based on a particular periodic arrangement of airholes and pure silica is designed for chromatic dispersion compensation. A two-concentric-core structure is obtained by introducing two different sizes of capillaries (for the airholes) and exhibits very high negative chromatic dispersion [-2200 ps/(nm km) at 1550 nm]. The variation of optogeometric parameters is also investigated to evaluate the tolerance of the fabrication. Finally, the bending influence on the modal characteristics shows that it is possible to tune the phase-matching wavelength over the C band by adjusting the diameter of the fiber.

Conception and characterization of a dual-concentric-core erbium-doped dispersion-compensating fiber.

We present an erbium-doped dispersion-compensating fiber made up of two asymmetric concentric cores, inner and outer matched claddings, and erbium located in the central core only. We demonstrate a high negative chromatic dispersion value [-700 ps/(nm km) at 1568 nm], significant modification of the gain spectrum compared with that of a classic erbium-doped fiber amplifier, and 30-dB peak small-signal gain at 1535 and 1553 nm.