Graded index 532HR/1064HT filter by glancing angle deposition

Glancing angle deposition is a novel method to prepare graded index coatings. By using this method and physical vapour deposition, ZrO2 is used to engineer graded index filter on BK7 glass substrate. Controlling the deposition rate and the periodic oscillation of oblique angle of deposited material, a 10-period graded index ZrO2 filter with high reflection near 532 nm and high transmittance at wavelength 1064 nm is fabricated. The causes of difference between the theoretical and experimental results are discussed in detail. The material properties and electron gun nonlinearity are possibly the main origins of the difference, which result in the variations in both thickness control and deposition rate of the Elm material.

Structural and optical properties of nanostructured TiO2 thin films fabricated by glancing angle deposition

TiO2 films deposited by electron beam evaporation with glancing angle deposition (GLAD) technique were reported. The influence of flux angle on the surface morphology and the microstructure was investigated by scanning electron microscopy. The GLAD TiO2 films are anisotropy with highly orientated nanostructure of the slanted columns. With the increase of flux angle, refractive index and packing density decrease. This is caused by the shadowing effect dominating film growth. The anisotropic structure of TiO2 films results in optical birefringence, which reaches its maximum at the flux angle alpha = 65 degrees. The maximum birefringence of GLAD TiO2 films is higher than that of common bulk materials. It is suggested that glancing angle deposition may offer an effective method to obtain tailorable refractive index and birefringence in a large continuous range. (c) 2006 Elsevier B.V. All rights reserved.

Preparation and characterization of nanostructured ZrO2 thin films by glancing angle deposition

ZrO2 films were prepared by electron beam evaporation with glancing angle deposition (GLAD) technique. The as-deposition and annealed ZrO2 films are all amorphous, different from that deposited at normal incidence. Due to the shadowing effect, a highly orientated structure composed of slanted columns formed, and the obtained films became the mixture of slanted columns and voids. The relationship among the effective refractive index, packing density and flux incident angle was investigated. The refractive index and packing density of ZrO2 films decrease with the increase of the incident angle. The in-plane birefringence of GLAD ZrO2 films was calculated. At the packing density of 0.576, the maximum birefringence is 0.037. (c) 2006 Elsevier B.V. All rights reserved.

Structure and optical properties of Nb2O5 sculptured thin films by glancing angle deposition

Nb2O5 sculptured thin. films deposited by electron beam evaporation with glancing angle deposition were prepared. Nb2O5 sculptured thin. films with tilted columns are optical anisotropy. XRD, SEM, UV-vis-NIR spectra are employed to characterize the microstructure and optical properties. The maximum of birefringence (Delta n) is up to 0.045 at alpha = 70 degrees with packing density of 0.487. With increasing the deposition angle, refractive index and packing density of Nb2O5 STF are decreasing. The relationship among deposition parameter, microstructure and optical properties was investigated in detail. (C) 2008 Elsevier B. V. All rights reserved.

Phylogenetic relationships of labeonine cyprinids of the disc-bearing group (Pisces : Teleostei)

Phylogenetic relationships of labeonine cyprinids of the disc-bearing group (Pisces. Teleostei). Zoological Studies 44 (1): 130-143. The disc-bearing group is composed of 4 currently recognized cyprinid genera: Discocheilus, Discogobio, Garra, and Placocheilus. This group is defined as having a lower lip modified to form a mental adhesive disc whose posterior margin is not continuous with the mental region, and includes 91 widely distributed species in tropical Africa and Asia. So far, it is represented in China by 28 species (about 1/3 of the total number) of all 4 genera. A phylogenetic analysis, based on 29 morphological characters scored from first-hand observations of 23 of the Chinese species examined, revealed that the disc-bearing group forms a monophyletic clade in which Garra is the basal lineage, and Placocheilus constitutes a subclade with the sister pair of Discocheilus and Discogobio. In such a phylogenetic framework, the validity of each genus of the disc-bearing group was evaluated. It was confirmed that Discocheilus, Discogobio and Placocheilus represent 3 valid cyprinid genera. Evidence provided in this phylogenetic analysis, incorporated with conclusions reached in the known literature, reveals that the monophyly and validity of Garra need to be further studied using observations of more Garra species. Additional characters should also be examined, as the characters utilized in this study and in Abebe's with Getahun's (1999) study are insufficient to resolve the monophyly of Garra.

The giant zooxanthellae-bearing ciliate Maristentor dinoferus (Heterotrichea) is closely related to folliculinidae

The small subunit rDNA sequence of Maristentor dinoferus (Lobban, Schefter, Simpson, Pochon, Pawlowski, and Foissner, 2002) was determined and compared with sequences from other Heterotrichea and Karyorelictea. Maristentor resembles Stentor in basic morphology and had been provisionally assigned to Stentoridae. However, our phylogenetic analyses show that Maristentor is more closely related to Folliculinidae. Our results support the creation of a separate family for Maristentor, Maristentoridae n. fam., and also confirm the phylogenetic grouping of Folliculindae, Stentoridae, Blepharismidae, and Maristentoridae, which we informally call 'stentorids'. Maristentor, rather than Stentor itself, appears to be most significant in understanding the origins of folliculinids from their aloricate ancestors. Our analyses suggest continued uncertainty in the exact placement of the root of heterotrichs with this phylogenetic marker.

Reduced divergence angle of photonic crystal vertical-cavity surface-emitting laser

The reduced divergence angle of the photonic crystal vertical-cavity surface-emitting laser (PC-VCSEL) was investigated in both theory and experiment. The photonic crystal waveguide possessed the weakly guiding waveguide characteristic, which accounted for the reduction of the divergence angle. The three-dimensional finite-difference time-domain method was used to simulate the designed PC-VCSEL, and a calculated divergence angle of 5.2 degrees was obtained. The measured divergence angles of our fabricated PC-VCSEL were between 5.1 degrees and 5.5 degrees over the entire drive current range, consistent with the numerical results. This is the lowest divergence angle of the fabricated PC-VCSEL ever reported.