Browsing by Subject "Chalcogenide"

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Open Access
Chalcogenide integrated hollow-core optical fibers for infrared light guidance
(2022-12) Khan, Asfandyar
The low-loss light transmission and broad bandwidth of hollow-core negative curvature fibers (NCFs) have a variety of applications in infrared (IR) light guidance, such as chemical detection, biomedical surgery, and laser delivery. Although silica is a material of choice for light guidance in the visible and near-IR spectra, transmission losses increase drastically in the mid-IR region; thus, other mid-IR transparent materials, such as chalcogenide glasses, are potentially preferred to guide the light. In this thesis, various cladding designs of arsenic trisulfide (As2S3) and arsenic triselenide (As2Se3) chalcogenide NCFs are numerically explored for low-loss transmission in the mid-IR region. A detailed numerical investigation in the optimization of As2S3 NCFs with tubular and elliptical cladding elements was performed, and a low-loss ellipse-nested tubular NCF design is proposed for mid-IR guidance. The effect on the transmission loss due to cladding elements of the proposed low-loss As2Se3 ellipse-nested tubular fiber design was investigated. Confinement and total loss of all fiber designs were numerically studied, and the single-mode light guidance performance of the proposed low-loss fiber design was explored. The bending loss performance of the fiber was analyzed in the targeted spectrum, and a dispersion control study was carried out to investigate the effect of the primary design parameters on the dispersion performance. A fabrication tolerance study was performed to investigate the effects of common fabrication issues on the proposed design’s guidance properties. In the second part of the thesis, NCFs with silica, chalcogenide, and chalcogenide-coated silica cladding elements were numerically investigated for low-loss near and mid-IR transmission. As2S3 coated silica NCF was compared to simple silica and simple As2S3 fiber to understand the effect of the As2S3 coating on the transmission loss of silica NCF. Fabrication of silica NCF through the stack-and-draw technique followed by micro-coating with As2S3 solution was performed to improve the transmission performance of the As2S3 coated silica glass-based NCF. Further modifications in the fabrication of the NCFs were realized for a thorough comparison with the numerical investigations.
Open Access
Development of multicore and tapered chalcogenide fibers for supercontinuum generation
(2016-12) Saleh, Abba Usman
The dramatic spectral broadening of an electromagnetic radiation as it propagates through a nonlinear medium is called Supercontinuum generation. Supercontinuum generation is indeed regarded as one of the prominent phenomenon in nonlinear optics and photonics with burgeoning applications in various fields such as spectroscopy, early cancer diagnostics, gas sensing, food quality control, uorescence microscopy e.t.c. Supercontinuum generation in optical fibers is however associated with three fundamental challenges: minimization of input power threshold, maximization of output power as well as output spectrum of a supercontinuum. Two unique fabrication approaches namely "Direct tapering" and "Multicore fibers" were proposed to address the aforementioned challenges. Chalcogenide nanowires were fabricated via direct tapering of chalcogenide glasses, and spectral broadening with extremely low peak power of 2 W was demonstrated. Multicore array of chalcogenide step index fibers were also fabricated using a new method. The fabricated step index fiber has a diameter 1.35 m which was engineered to have a zero dispersion wavelength (ZDW) around 1100 nm with a pump of center wavelength at 1550 nm .Using split step Fourier method, it was shown that the fiber possesses a great potential for severe spectral broadening. Supercontinuum generation with the as drawn fiber, encountered challenges as well as proposed solutions were demonstrated and discussed.
Open Access
Tunable ring-coupled Mach-Zehnder interferometer based on lithium niobate
(Taylor and Francis, 2014) Solmaz, M. E.
The fabrication and characterization are reported of a Fano resonance-based electro-optically tunable ring resonator-coupled Mach-Zehnder interferometer device based on a chalcogenide-lithium niobate hybrid waveguide system. The experiments reveal inherent asymmetric lineshapes that can be flipped to a near symmetrical resonance by applying a dc voltage of ~10 V across the electrode at the MZI non-resonator arm. Further increase in voltage yields the reverse of initial asymmetry. The optical filter-based transfer-matrix model easily explains the experimental data and indicates ways to further enhance the usability of such architecture. © 2014 Taylor and Francis.