To investigate the effects on moisture sorption behavior of wood caused by the removal of chemical components, Populus euramericana flour (40 to 60 mesh) was divided into four groups: untreated, extractives removed, hemicellulose removed, and matrix removed. The samples at the fiber saturation point and under oven-dried conditions were separately exposed to relative humidities of 11%, 45%, and ...

We investigate dual pump Fiber Optical Parametric amplifier (FOPA) for wide gain bandwidth. With careful optimization of parameters of fiber used for amplification, dual pump FOPAs can effectively serve as high gain saturated, broadband amplifiers. Type of fiber and its characteristics strongly affect the peak gain and bandwidth of the dual pump FOPA. We attempt to optimize the fiber parameters...

A coupled drying model for wood is proposed by introducing a dynamic capillary pressure. The pressures of non-wetting phase, the wetting phase, and the capillary pressure at equilibrium has been considered as non-static; this approach includes a two-scale model. According to numerical results, liquid, water vapor and air dynamics in the chamber have strong interactions with re-homogenization in...

We report on the observation of various bound states of dispersion-managed (DM) solitons in a passively mode-locked erbium-doped fiber ring laser at near zero net cavity group velocity dispersion (GVD). The generated DM solitons are characterized by their Gaussian-like spectral profile with no sidebands, which is distinct from those of the conventional solitons generated in fiber lasers with la...

In this study, beech wood was treated in hot oil and in hot air to determine the differences in the effects of the two processes on the physical properties of the wood. Heat treatment was conducted at temperatures of 160, 190, and 220 °C for 2 h at atmospheric pressure. After the heat treatment, various properties of the wood, including mass increase in hot oil treatment (wt% gain), mass loss i...

Ultrasonic energy was applied to assist the wood vacuum drying process. At a drying temperature of 60°C, the absolute pressure was either 0.05 MPa or 0.08 MPa; the ultrasonic power and frequency were 100 W and 28 kHz, respectively. The results showed that the effective water diffusivity of the specimens dried by the ultrasonic assisted vacuum drying at 0.05 MPa or 0.08 MPa were higher than that...

We report the influence of higher order modes (HOMs) in large mode fibers operation in Q-switched oscillator configurations at ~2 μm wavelength. S(2) measurements confirm guiding of LP(11) and LP(02) fiber modes in a large mode area (LMA) step-index fiber, whereas a prototype photonic crystal fiber (PCF) provides nearly single-mode performance with a small portion of light in the LP(11) mode. T...

We present a detailed investigation of pulse width and spectral dynamics of an Er-doped soliton fiber ring laser, mode-locked by a carbon-nanotube-polymer composite. The laser is stable and produces ∼ 650 fs pulses at a fundamental repetition rate of 20.8MHz. The carbon nanotube saturable absorber has a low saturation intensity of ∼ 18.9 MW/cm and a 16.9% reduction in absorption (due to saturat...