Wood pulp fibers possess strength and modulus properties which compare favorably with glass fibers when the differences in fiber densities are considered. Softwood pulp fibers with fiber aspect ratios near 100 are readily dispersed into highdensity polyethylene or isotactic polypropylene with the aid of carboxyic dispersing agents to form mixtures containing 50 weight-percent wood pulp which can be readily injection molded. The mechanical properties of the molded specimens were similar for all types of pulp including Kraft (bleached and unbleached), mechanical and chemical-mechanical pulps, waste pulps, and reclaim newspapers. Comparisons of the stiffness/weight efficiencies revealed that pulp composites equal or exceed the stiffness of most traditional materials of construction including steel, aluminum, glass-fiber composites, and talcfilled polyolefins, while retaining a major material cost advantage. The measured strength values of the pulp composites were less than the theoretically predicted values due to the presence of voids created by the formation of volatiles during processing. Mechanical pulps which were available in dry form were preferred because of lower cost and ease of handling. Wood fibers are non-abrasive so that relatively large concentrations may be incorporated into polyolefins without causing serious machine wear during mixing and fabrication.

We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

Water-ground Phlogopite micas were classified into narrow particle-size distributions containing flakes with well-defined diameters and thicknesses in order to evaluate the influence of particle size and flake aspect ratio on the mechanical properties of mica-filled polypropylenes. For the purposes of comparison, most of the injection-molded specimens contained 40 percent (by weight) mica. As expected, the flexural and tensile modulus values increased in proportion to the aspect ratio over the range from 30 to 60 to a maximum of 8 GPa. The measured tensile strengths of the mica-filled polypropylenes increased substantially as the flake diameter became smaller, but did not correlate with the flake aspect ratio. The attainable properties were frequently dependent upon the method of mixing, and considerable care was necessary to ensure proper dispersion and adequate coupling. Intensive mixing, as in a Gelimat Mixer, may cause in situ delamination and particle-size reduction of the mica filler particles, leading to a marked increase in tensile strength of the resulting composite. The mica-filled compounds could be reprocessed many times without significant loss of properties, particularly compounds having mica particles less than 40 pm in diameter. The fracture energies (notched Izod) and the heat-distortion temperatures were not appreciably influenced by the size or aspect ratios of the mica within this range. Increased fracture toughness could be achieved by reducing the mica concentration or employing a polypropylene copolymer. Guidelines are presented to indicate the preferred characteristics of mica fillers and the influence of mixing conditions on performance.

Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX We present a 100 kHz optical parametric chirped pulse amplifier (OPCPA) developed for strong-field attosecond physics and soft-X-ray transient absorption experiments. The system relies on noncollinear potassium titanyl arsenate (KTA) booster OPCPAs and is pumped by a 240 W, 1.1 ps Yb:YAG Innoslab chirped pulse laser amplifier. Two optically synchronized infrared output beams are simultaneously available: a 430 µJ, 51 fs, carrierenvelope phase (CEP) stable beam at 1.55 µm and an angular-dispersion-compensated, 125 µJ, 73 fs beam at 3.1 µm.High-repetition-rate (i.e., >> 10 kHz) ultrafast laser sources operating in the near-infrared (NIR, 0.8-3 µm) and the midinfrared (MIR, 3-30 µm) combined with state-of-the-art chargedparticle detection systems enable the investigation of strong-field physics in hitherto unexplored regimes [1]. Long-wavelength drivers can also be exploited to push the cutoff photon energy in high-harmonic generation (HHG) towards, and into the soft-X-ray regime (SXR, > 120 eV) [2]. For the study of biomolecules in their natural aqueous environment, the so-called water window (284-543 eV) constitutes a particularly interesting spectral range [2]. However, the unfavorable scaling of the single-atom response in HHG,  -(5-6) , can only partly be overcome by phase-matching schemes [3]. Therefore, for high single-shot SXR photon numbers, optical driver pulse energies at the multi-100 µJ level are required even at center wavelengths below 2 µm, which has so-far limited table-top water-window SXR sources to repetition rates of ≤ 1 kHz [2].Diode-pumped, Tm-doped fiber chirped pulse laser amplification near 2 µm is a promising, scalable technology for pumping water-window SXR sources. Recently, 252 µJ, sub-50 fs

We present the first study of Q-switched Alexandrite lasers under continuous-wave diode-pumping with operation up to 10 kHz repetition rates in TEM₀₀, with spatial quality M² 1.15. With a pulsed-diode dual-end-pumped design, pulse energy is scaled to a record level of 3 mJ. We also demonstrate, for the first time, cavity-dumped Q-switching of diode-pumped Alexandrite lasers under continuous-wave and pulsed diode-pumping, up to 10 kHz. Pulse energy of 510 μJ is demonstrated with 3 ns pulse duration and 170 kW peak power, in TEM₀₀ with M² < 1.2. Second harmonic generation of the cavity-dumped Q-switched pulses was used to generate UV wavelength 379 nm with conversion efficiency of 47%.

This paper presents the highest average power passively Q-switched Nd:vanadate laser, to the best of our knowledge. A maximum average output power greater than 11 W was demonstrated using a Nd:YVO4 bounce geometry laser operating at 1064 nm in TEM00 mode, with a spatially stigmatic design. Pulse energies greater than 58 µJ and peak powers in excess of 1.9 kW were obtained; the maximum repetition rate recorded was 190 kHz, close to the upper limit achievable with Cr4+:YAG saturable absorbers.

We present the investigation of diode-side-pumping of Alexandrite slab lasers in a range of designs using linear cavity and grazing-incidence bounce cavity configurations. An Alexandrite slab laser cavity with double-pass side pumping produces 23.4 mJ free-running energy at 100 Hz rate with slope efficiency ~40% with respect to absorbed pump energy. In a slab laser with single-bounce geometry output power of 12.2 W is produced, and in a double-bounce configuration 6.5 W multimode and 4.5 W output in TEM mode is produced. These first results of slab laser and amplifier designs in this paper highlight some of the potential strategies for power and energy scaling of Alexandrite using diode-side-pumped Alexandrite slab architectures with future availability of higher power red diode pumping.

Satellite-based remote sensing using laser-based lidar techniques provides a powerful tool for global 3-D mapping of atmospheric species (e.g. CO 2 , ozone, clouds, aerosols), physical attributes of the atmosphere (e.g. temperature, wind speed), and spectral indicators of Earth features (e.g. vegetation, water). Such information provides a valuable source for weather prediction, understanding of climate change, atmospheric science and health of the Earth ecosystem. Similarly, laser-based altimetry can provide high precision ground topography mapping and more complex 3-D mapping (e.g. canopy height profiling). The lidar technique requires use of cutting-edge laser technologies and engineered designs that are capable of enduring the space environment over the mission lifetime. The laser must operate with suitably high electrical-to-optical efficiency and risk reduction strategy adopted to mitigate against laser failure or excessive operational degradation of laser performance.