Presence and Partitioning Behavior of Polyfluorinated Iodine Alkanes in Environmental Matrices around a Fluorochemical Manufacturing Plant: Another Possible Source for Perfluorinated Carboxylic Acids?

The indistinct origins of some ubiquitous perfluorinated alkyl acids have attracted great attention in recent decades. In this present work, even-chained polyfluorinated iodides (PFIs), a group of volatile perfluorinated compounds (PFCs), including four perfluorinated iodine alkanes (FIAs) and three polyfluorinated telomer iodides (Fits) were confirmed to be present in the environment. A wide concentration range was found for FIAs at 1.41 to 3.08 x 10(4) pg/L, and for FTIs at 1.39 to 1.32 x 10(3) pg/L in the ambient air collected around a fluorochemical manufacturing plant in Shandong province, northern China. Whereas for surface soils, most of these PFIs were below detection limits and only small amounts of analytes with higher carbon chain (such as perfluorododecyl iodide and 1H,1H,2H,2H-perfluorodecyl iodide, 16.6-499 pg/g) could be sporadically detected. The presence of the PFIs in different environmental matrices in the investigated area and calculated vapor pressures (0.095-20.4 Torr) verify that they can be considered as volatile organic chemicals and easily be released into the atmosphere. Together with reported degradation ability and long-range transport potential, the identification of these PFIs indicates that unintentional release during the telomer reaction process might also be another route for the formation and distribution of certain polyfluorinated alcohols, aldehydes, and carboxylic acid derivatives under oxidative conditions in the environment

Highly dynamic and versatile pulsed fiber amplifier seeded by a superluminescence diode

We propose and investigate a high power superluminescence diode (SLD) as a pulsed seed source for a highly dynamic and versatile pulse fiber amplifier system. The SLD provides, contrary to conventional Fabry-P,rot laser diodes, a smooth and broad output spectrum which is independent of the input pulse parameters. The output pulses from the SLD are as short as 10 ns with up to 150 mW peak power. Moreover, the pulses can be directly shaped by modulating the injection current of the SLD. Pulse shaping in an amplifier configuration is demonstrated without the observation of stimulated Brillouin scattering (SBS) due to the provided spectral bandwidth of 10 nm FWHM. Further spectral shaping was realized with a band pass filter in the amplifier chain

Novel concept of timing jitter reduction of a passively Q-switched microchip lasers using self-injection seeding

We present an efficient and simple technique for reduction of timing jitter in passively Q-switched microchip-laser using self-injection seeding using an optical-fiber as a delay-line and reduce the jitter by several orders of magnitude

105 kHz, 85 ps, 3 MW microchip laser fiber amplifier system for micro-machining applications

We report on a fiber amplified passively Q-switched microchip-laser delivering 85ps, 3MW pulses with 105kHz repetition rate. An all-optical synchronization technique reducing the mean pulse to pulse jitter of the microchip laser to 40ps is demonstrated for the first time. In comparison with existing setups at comparable average powers, the repetition rate is nearly on order of magnitude higher and the pulse duration is one order of magnitude shorter, making it a formidable micromachining source with high ablation rates

SBS suppression in high power fiber pulse amplifiers employing a superluminescence diode as seed source

SBS suppression in a high power ns fiber amplifier employing a pulsed SLD as seed source. It emits a 10nm FWHM spectrum free of longitudinal modes at 150mW peak power and 5ns rise / fall time

Improved parametric generation of light in optical fibers

It is shown that by introducing attenuation for one of the FWM partners, it is possible to substantially improve the parametric generation of the other FWM partner in an optical fiber

Suppression of stimulated Raman scattering in high-power fiber laser systems by lumped spectral filters

We present a systematic study on the inhibition of stimulated Raman scattering by lumped spectral filters both in passive optical transport fibers and in fiber amplifiers. This study reveals the parameters that have the strongest influence on the suppression of the Raman scattering (such as the attenuation at the Raman wavelength and the insertion losses at the signal wavelength). These parameters have to be optimized in order to achieve the desired Raman inhibition and/or to minimize the loss in amplifier efficiency. The study is concluded with realistic predictions on the use of spectral filtering elements for Raman scattering inhibition in real-world high power fiber amplifiers. Thus, using for example 10 lumped spectral filters with 20 dB effective Raman attenuation and less than 0.25 dB insertion losses, a maximum Raman threshold increase by a factor of 3 is expected. In this context, long period gratings are proposed as promising filtering elements for Raman inhibition in high power fiber amplifiers. In order to experimentally verify the theoretical predictions and the suitability of long period gratings, a fiber amplifier consisting of 2 m active Ytterbium doped fiber was built. Three long period gratings were consecutively inserted at different positions along the fiber, and the Raman threshold was determined for each situation. It is shown that, with three long period gratings, the Raman threshold (defined as the 20 dB ratio of Raman to signal output power) was increased by about 60%, which offers a good agreement with the theoretical predictions

Reduction of timing-jitter in a passively Q-switched microchip laser using self-injection seeding

We present a simple technique for the timing jitter reduction in passively Q-switched microchip-lasers by self-injection seeding using a fiber delay line. The jitter is reduced by several orders of magnitude