Parametric Wavelength Conversion From Conventional Near-Infrared to Visible Band

The feasibility of distant wavelength conversion in photonic crystal fiber was explored. The one-pump parametric architecture was used to demonstrate translation from the conventional (1550 nm) to visible (500 nm) band. Experimental results are reported, which demonstrate the conventional-to-visible conversion of single- and multiple-channel signals encoded in the nonreturn-to-zero format     

Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal

We have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p-hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures T_g determined via thermal mechanical analysis. The T_g value of the blend E is shifted towards the T_g of PLC; T_g of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity α_L values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more than 60 K Copyright © 2004 Society of Chemical Industry     

Tunable Parametric All-Fiber Short-Wavelength IR Transmitter

In this paper, the performance of an all-fiber short-wave IR (SWIR) transmitter with wideband tunability and high peak power is reported. Transmitter construction relied on parametric process in highly nonlinear fiber to convert a seed laser at 1260 nm to 2155 nm SWIR channel with record 39 dB efficiency and translation over 900 nm spectral range. We demonstrated 61 W of peak converted power at 2 $mu$m and 26 W at 2.15 $mu$ m. Efficient conversion was made possible by engineered fourth-order dispersion of the highly nonlinear fiber and construction of a low-noise pump source in a 1550 nm band.      

Polymer cosolvent system

Summary The preferential adsorption parameter of poly(phenyl methacrylate), poly[4-(1,1,3,3- tetramethylbutyl) phenyl methacrylate] and poly(4-tert-butyl styrene) in the mixture THF/water has been determined by exclusion chromatography (GPC) and differential refractometry and dialysis equilibrium (DR). The general behaviour of the polymers studied in this mixture is very similar, water is preferentially adsorbed by the polymer at low water content. The results are discussed in relation to the rigidity of the macromolecular chains and the hydrophobic degree of the substituent group in the aromatic ring.     

Multicast Parametric Synchronous Sampling of 320-Gb/s Return-to-Zero Signal

Technology for simultaneous demultiplexing of subrate tributaries is described and applied to 320-Gb/s return-to-zero input. The parametric architecture is scalable with respect to processed input rate and relies on cascaded all-optical multicasting and subrate sampling. Processing of 320-Gb/s input was achieved by creating eight channel copies, followed by a 20-THz-wide parametric gate. Multicasting was based on a self-seeded two-pump broadband fiber-optic parametric amplifier. The architecture was used to demonstrate error-free parallel demultiplexing of eight 320-Gb/s tributary channels at 40 Gb/s.     

Viscometric and preferential adsorption behaviour of poly(4-tert-butylphenyl methacrylate) in tetrahydrofuran/chloroform

The viscometric behaviour of poly(4-tert-butylphenyl methacrylate) in the solvent mixture tetrahydrofuran/chloroform has been investigated. There is qualitative agreement between variations in [η] and predictions from the Dondos and Patterson theory. The role of the preferential adsorption of one of the solvents on the polymer was considered. The experimental adsorption coefficients λ1 are discussed in this particular mixture where G^E < 0. In this binary solvent rthe kθ values of the polymer are similar in the three different mixed solvent compositions studied.     

Mechanical and dielectric properties of bulky side chain poly(methacrylates). Analysis of the low frequency phenomena. 1: Poly(5-indanyl methacrylate)

This paper composes the dynamic mechanical and dielectric relaxation properties for Poly (5-indanyl methacrylate) (P51M), a polymer with a bulky side chain. Measurements were carried out from about ?100°C to near 250°C. A secondary loss peak was observed in dielectric measurements at room temperature (20°C at 0.1 Hz.), whereas nothing was resolved in the mechanical spectrum. A prominent α relaxation associated with the glass transition was also observed near 107°C at 0.1 Hz. in the dielectric and the mechanical spectra. Dipolar dielectric loss overlapped with conductivity at high temperatures and low frequencies. A new method to split the conductive, interfacial, and dipolar contributions to the spectrum is proposed.     

Inclusion complexes containing poly(?-caprolactone)diol and cyclodextrins. Experimental and theoretical studies

Inclusion complexes (ICs) between poly(?-caprolactone)diol (PEC) with α-cyclodextrin (α-CD) (α-CD-PEC) and γ-cyclodextrin (γ-CD) (γ-CD-PEC) were prepared and characterized by FT-IR, ¹H NMR, thermogravimetry, surface activity and wettability measurements. The thermal stabilities of the inclusion complexes are very similar. The thermal stability of PEC is better than ICs and CDs. Stable monolayers of PEC and α-CD-PEC and γ-CD-PEC complexes have been obtained at the air-water interface using the Langmuir Technique. The surface pressure-area isotherms (π-A) were found to be of different types, depending on the CD utilized. From the surface free energy values of PEC and ICs it was possible to conclude that ICs are more hydrophobic than cyclodextrins. PEC is the most hydrophobic. The surface parameters the minimum area A₀, the critical surface pressure π_c, and static elasticity ?₀ were also estimated for ICs and PEC. In order to describe the experimental results, molecular dynamic simulation (MDS) was performed. In addition, the physical properties that stabilize CD-CD, CD-polymer and CD-solvent interactions were elucidated by MDS. Theoretical results have demonstrated that complexes are stabilized by hydrophobic interactions between the cavity of CDs and the -(CH₂)₅-units of PEC, and also by hydrogen-bond formation between the hydroxyl groups situated along the rim of CD molecules threaded onto the PEC chain. CD-CD hydrogen-bond formation is maximized in 1:2 γ-CD-PEC complex and 1:1 α-CD-PEC complexes.