Linearly chirped mid-infrared supercontinuum in all-normal-dispersion chalcogenide photonic crystal fibers.

We demonstrate all-normal dispersion supercontinuum generation in chalcogenide photonic crystal fibers pumped at 2070-2080 nm with a femtosecond fiber laser. At 2.9 kW peak power, the generated supercontinuum has a 3 dB bandwidth of 27.6 THz and -20 dB bandwidth of 75.5 THz. We experimentally investigated the supercontinuum evolution inside our sample fiber at various peak powers and fiber lengths and study the impact of fiber water absorption on the generated supercontinuum spectrum. Multiple tests with fiber length- ranging from 0.34 to 10 cm-provide insight on pulse evolution along fiber length. Our simulations, which utilizes the generalized nonlinear Schrodinger equation model, match perfectly the experiments for all tested pump powers and fiber lengths, and confirm that the output pulse has a linear chirp, allowing linear pulse compression.

Fiber fuse in chalcogenide photonic crystal fibers.

We observe fiber fuse in tapered GeAsSe photonic crystal fibers (PCF) at around 7 MW/cm2 of intra-core intensity. Vertically cleaved facets from the un-tapered regions and the tapered regions were imaged. The images show shallow voids of different shapes confined to the fiber core. After longitudinally polishing a segment of the PCF, we imaged the PCF internal structure's top view, revealing the fuse voids' geometries and periodicity. In addition, fiber fuse was terminated in one PCF sample by a fast laser shutdown, hence saving a small segment from catastrophic damage. Four-wave-mixing was performed on this transmissive segment to estimate the dispersion. The results yielded an evident hole-pitch ratio change after fiber fuse. To our knowledge, this is the first report of fiber fuse on non-silica glass fibers and the first study of its aftermath on this un-destroyed segment of PCFs.

Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion.

We experimentally demonstrate wavelength conversion in the 2 µm region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of -25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 µm. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 µm pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW.

Kerr nonlinearity and dispersion characterization of core-pumped thulium-doped fiber at 2 µm.

A nonlinear coefficient of 3.6-4.1 W-1 km-1 and group velocity dispersion of -20 ps2/km of a commercial core-pumped thulium-doped fiber have been evaluated using degenerate four-wave mixing at 2 µm. The anomalous dispersion behavior of the fiber has been confirmed by linear measurements with an all-fiber Mach-Zehnder interferometer (MZI). Additionally, no pump-induced dispersion changes due to excitation of Tm3+ cations have been detected. These characteristics make these fibers attractive for pulsed fiber laser applications. A nonlinear-polarization rotation mode-locked laser involving nonlinear polarization evolution directly in the doped fiber is demonstrated.

High-power parametric conversion from near-infrared to short-wave infrared.

We report the design of an all-fiber continuous wave Short-Wave Infrared source capable to output up to 700 mW of power at 1940 nm. The source is tunable over wavelength intervals comprised between 1850 nm and 2070 nm depending on its configuration. The output can be single or multimode while the optical signal to noise ratio ranges from 25 and 40 dB. The architecture is based on the integrated association of a fiber optical parametric amplifier and a Thulium doped fiber amplifier.

Data transmission in long-range dielectric-loaded surface plasmon polariton waveguides.

We demonstrate the data transmission of 10 Gbit/s on-off keying modulated 1550 nm signal through a long-range dielectric-loaded surface plasmon polariton waveguide structure with negligible signal degradation. In the experiment the bit error rate penalties do not exceed 0.6 dB over the 15 nm wavelength range and received optical power between -7 and 3 dBm.

Large second harmonic generation enhancement in Si3N4 waveguides by all-optically induced quasi-phase-matching.

Efficient second harmonic generation in integrated platforms is usually achieved by resonant structures, intermodal phase-matching or quasi-phase matching by periodically poling ferroelectric waveguides. However, in all these structures, it is impossible to reconfigure the phase-matching condition in an all-optical way. Here, we demonstrate that a Watt-level laser causes a periodic modification of the second-order susceptibility in a silicon nitride waveguide, allowing for quasi-phase-matching between the pump and second harmonic modes for arbitrary wavelengths inside the erbium band. The grating is long-term inscribed, and leads to a second harmonic generation enhancement of more than 30 dB. We estimate a χ (2) on the order of 0.3 pm/V, with a maximum conversion efficiency of 0.05% W-1. We explain the observed phenomenon with the coherent photogalvanic effect model, which correctly agrees with the retrieved experimental parameters.