Browsing by Subject "Tubes (components)"

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Open Access
Observation of polarized gain from aligned colloidal nanorods
(Royal Society of Chemistry, 2015) Gao, Y.; Ta, V. D.; Zhao, X.; Wang Y.; Chen R.; Mutlugün, E.; Fong, K. E.; Tan S.T.; Dang C.; Sun, X. W.; Sun, H.; Demir, Hilmi Volkan
In recent years, colloidal semiconductor nanorods have attracted great interest for polarized spontaneous emission. However, their polarized gain has not been possible to achieve so far. In this work we show the highly polarized stimulated emission from the densely packed ensembles of core-seeded nanorods in a cylindrical cavity. Here CdSe/CdS dot-in-rods were coated and aligned on the inner wall of a capillary tube, providing optical feedback for the nanorod gain medium. Results show that the polarized gain originates intrinsically from the aligned nanorods and not from the cavity and that the optical anisotropy of the nanorod ensemble was amplified with the capillary tube, resulting in highly polarized whispering gallery mode lasing. The highly polarized emission and lasing, together with easy fabrication and flexible incorporation, make this microlaser a promising candidate for important color conversion and enrichment applications including liquid crystal display backlighting and laser lighting. This journal is © The Royal Society of Chemistry.
Open Access
Passive polarization filtering in negative curvature hollow-core fibers
(SPIE - International Society for Optical Engineering, 2023-10-05) Siddiqui, Muhammad Zain; Akosman, A. E.; Ordu, Mustafa; Yin, Shizhuo; Guo, Ruyon
A novel negative curvature hollow-core fiber (NCF) design is proposed capable of spectral and polarization filtering in the near-infrared region. The designed six-tube silica-based NCF contains nest elements in the form of suspended tubes radially anchored with a pole to the outer cladding in the vertical direction. In contrast, standard nested cladding elements without any suspension are used through the horizontal axis. This fiber configuration introduces an asymmetry in the core, which helps maintain the orthogonal X and Y polarization states in the fiber core. Pole anchors in vertically positioned tubes only give rise to the spectral filtering confinement loss profile for a vertically polarized state. Based on the geometrical optimization of the fiber, we achieved an improved birefringence on the order of 10-5 with filtered wavelength losses below 0.01 dB/km in the wavelength range of 1.4 µm to 1.7 µm. The operational bandwidth, polarization extinction ratio, filtered wavelengths, birefringence, and modulation depth loss can be tuned by optimizing the fiber parameters, including outer tube thickness, nest tube diameter, and pole dimensions. This proposed fiber design with selective transmission spectrums has untapped potential sensing capabilities in hollow-core negative curvature fibers. © 2023 SPIE. All rights reserved.
Open Access
Water-soluble non-polymeric electrospun cyclodextrin nanofiber template for the synthesis of metal oxide tubes by atomic layer deposition
(Royal Society of Chemistry, 2014) Celebioglu A.; Vempati S.; Ozgit Akgun, C.; Bıyıklı, Necmi; Uyar, Tamer
We report on the suitability of water-soluble non-polymeric electrospun cyclodextrin (CD) nanofiber templates by using atomic layer deposition (ALD) to yield metal oxide tubes. To demonstrate this, water-soluble electrospun CD nanofibers were chosen as template to produce metal oxide tubes where we have tested two examples of ALD coatings, namely, Al2O3 and ZnO. After the ALD coating on the CD nanofibers, the CD core is simply dissolved in water to yield metal oxide tubes. Morphological investigations suggested that Al2O3 is smoother in contrast to ZnO which shows a grainy structure. Structural characterization evidenced amorphous Al2O3 and highly crystalline ZnO. Given the applicability of Al2O3 and ZnO in various contexts the ionic states of Al, Zn and O are also investigated. After the washing step to remove the CD core, Al2O3 developed some hydroxylation, while ZnO hosts various oxygen related functional groups.