Excitation dependent losses and temperature increase in various hollow waveguides at 10.6 μm

Theoretical and experimental studies have been made on excitation dependent transmission properties of various hollow waveguides at 10.6 μm. A heat problem of the waveguide has been experimentally treated when high powered CO₂ laser light is launched.     

Infrared hollow fiber with a vitreous film as the dielectric inner coating layer

A vitreous material with an optimum reflective index of 1.41 for dielectric metallic hollow fiber is used for what is believed to be the first time. A smooth vitreous film is formed by the treatment of a hardener at room temperature by using the liquid-phase coating technique. Low-loss properties were obtained in both the infrared and visible wavelength regions, and the fibers are of high durability when sterilized. This hollow fiber is promising for use in medical applications or other harsh environments.     

Synthesis, properties, and ambipolar organic field-effect transistor performances of symmetrically cyanated pentacene and naphthacene as air-stable acene derivatives

5,12-Dicyanonaphthacene and 6,13-dicyanopentacene have been synthesized for the first time. The LUMO and HOMO levels are deepened as predicted and fabricated organic field-effect transistors (OFETs) showed ambipolar responses with carrier mobilities of 10(-3) cm(2)/V·s.     

Novel broadband dispersion compensating photonic crystal fibers: Applications in high-speed transmission systems

This paper reveals a novel dispersion compensating photonic crystal fiber (DC-PCF) for wide-band high-speed transmission systems. The finite-difference method with an anisotropic perfectly matched absorbing layers boundary condition is used to investigate the guiding properties. The designed novel DC-PCF shows that it is possible to obtain a larger negative dispersion coefficient, better dispersion slope compensation, and confinement losses less than 10^?4 dB/m in the entire S+C+L telecommunication band by using a modest number of design parameters. The proposed module can be used in 40 Gb/s dense wavelength division multiplexing (DWDM) systems in optical fiber communication networks.     

Design and analysis of novel highly nonlinear photonic crystal fibers with ultra-flattened chromatic dispersion

The present article describes novel highly nonlinear photonic crystal fibers (HN-PCFs) with flattened chromatic dispersion and low confinement losses. The proposed design has been simulated based on the finite-difference method with anisotropic perfectly matched layers absorbing boundary condition. It is proved that the design novel HN-PCFs is obtained a nonlinear coefficient greater than 45 W⁻¹ km⁻¹ and low dispersion slope −0.009 ps/(nm².km) at 1.55 μm wavelength. In addition, results from numerical simulation show that the ultra-flattened dispersion of 0 ± 0.65 ps/(nm.km) can be obtained in a 1.36-1.62 μm wavelength range with confinement losses lower than 10⁻⁷ dB/m in the same wavelength range. Another advantage of the proposed HN-PCFs is that it possessed modest number of design parameters.     

Broadband nearly-zero ultra-flattened dispersion single mode index guiding holey fiber

This paper proposes and demonstrates a novel type of silica index guiding holey fibers (IGHFs) that has two cladding layers at the defective innermost structures. The proposed IGHFs exhibit remarkable chromatic dispersion properties such as nearly-zero and flattened dispersion over a wide spectral range and single mode guidance along with very low confinement loss. The numerical results indicate that 5 air-hole rings of nearly zero ultra-flattened dispersion single mode IGHFs can be designed with desire flattened dispersion of over a 340 nm bandwidth including the entire band of interest with low confinement loss of less than 10⁻⁶ dB/m.     

Aberrant expression of sialidase and cancer progression

Aberrant sialylation is closely associated with the malignant phenotype of cancer cells including metastatic potential and invasiveness. However, its biological significance and molecular mechanisms have yet to be fully elucidated. To determine causes and consequences, we have focused attention on mammalian sialidases, which cleave sialic acids from gangliosides and glycoproteins. The four types of human sialidases identified to date behave in different manners during carcinogenesis. One, found in the lysosomes, shows down-regulation in cancers, promoting anchorage-independent growth and contributing to metastatic ability, while another, found in the plasma membranes, exhibits marked up-regulation, resulting in suppression of apoptosis. The present review summarizes mostly our results on aberrant expression of sialidases and their possible roles in cancer progression.     

Robust hollow devices and waveguides for Er:YAG laser radiation

Fluorocarbon-polymer (FCP) coated silver hollow stainless steel (St) devices and waveguides have been developed for Er:YAG laser radiation. Full liquid phase techniques have been adopted to coat the silver and FCP layers inside the stainless steel hollow structure. Both straight and bent robust hollow devices have been fabricated as the output optical elements for the delivery system of medical Er:YAG lasers. A robust hollow waveguide with the length of about 1.6 m has also been realized as an actual delivery system.     

Small-bore fluorocarbon polymer-coated silver hollow glass waveguides for Er:YAG laser light

Several types of fluorocarbon polymer (FCP)-coated silver hollow glass waveguides have been fabricated for Er:YAG laser delivery by using the improved wet chemical technique and dynamic coating procedure. The straight losses of 2 m long 700 μmØ and 540 μmØ waveguides are 0.4 and 1.0 dB, respectively. The transmission losses of these waveguides are below 1.5 dB even when the waveguides are bent to 180° with the bending radius of either 20 or 15 cm. The waveguides with the small diameters of 320 and 200 μm have also been developed for clinical treatment, which exhibit low enough transmission losses for Er:YAG laser light.     

Centroid shift of power flow in gently bent circular hollow or dielectric waveguide

We show that the centroid of power flow in gently bentcircular waveguides does not necessarily shift towards the outward direction of bending.