Stacking the Equiangular Spiral

We present an algorithm that adapts the mature Stack and Draw (SaD) methodology for fabricating the exotic Equiangular Spiral Photonic Crystal Fiber. (ES-PCF) The principle of Steiner chains and circle packing is exploited to obtain a non-hexagonal design using a stacking procedure based on Hexagonal Close Packing. The optical properties of the proposed structure are promising for SuperContinuum Generation. This approach could make accessible not only the equiangular spiral but also other quasi-crystal PCF through SaD

Spiral photonic crystal fibers

This thesis is concerned with the study of special types of photonic crystal fibers (spiral) and their optical properties. The work is carried out using simulation techniques to obtain the modal field profile and properties for the designs. The method used in solving the Maxwell’s equations is the full vectorial finite element method with the implementation of penalty function and perfectly matched layer. The penalty function is used to eliminate nonphysical solutions. The perfectly matched layer is integrated to absorb rays of light traveling away from the core. These rays are absorbed by the layer and do not reflect back to negatively influence the results. The spiral shapes are implemented in the distribution of the holes in the cladding region of the photonic crystal fiber to determine the photonic crystal fiber properties. Three different spirals have been introduced which are equiangular, Archimedean and Fermat’s spiral. The study of the effective refractive index, effective area and dispersion with varying spiral parameters have been carried out and the results are analyzed to understand the effect of each parameter. The variation of similar parameters in the spirals leads to similar variation in the optical properties under consideration. Furthermore, the equiangular spiral photonic crystal fibers (ES-PCF) have been investigated in two different dimensional scales. The scales are in comparison with the wavelength of operation in the first case when core size is larger than the operating wavelength. In this case the total dispersion of the fiber has slightly higher values than the material dispersion but similar curve and slope. On the other hand, when the core size is comparable with the wavelength of operation, the dispersion is varying significantly with varying the spiral parameters. The effective area can be made very small and therefore the nonlinearity of the fiber very large to facilitate non-linear applications such as super continuum generation. The equiangular spiral photonic crystal fiber has been modified slightly where the position of holes in the third ring are shifted further from the center and their size is much bigger. This manipulation is proposed in an algorithm in this thesis to facilitate the fabrication of ES-PCF using an adaptive stack and draw technique. The design shows similar optical behavior to an ideal spiral and its dispersion has been tailored for supercontinuum generation

Ultra-broadband mid-infrared supercontinuum generation through dispersion engineering of chalcogenide microstructured fibers

We demonstrate numerically that the use of dispersion-engineered microstrucured fibers made with chalcogenide glasses allows one to generate ultrabroadband supercontinuum spectra in the mid-infrared region by launching optical pulses at a suitable wavelength. As a specific example, numerical simulations show that such a 1 cm long fiber, made with Ge11.5As24Se64.5 glass and pumped at a wavelength of 3.1 μm using short pulses with a relatively modest peak power of 3 kW, can produce a spectrum extending from 1.3 μm to beyond 11 μm (more than 3 octaves). We consider three fiber structures with microstrucured air holes in their cladding and find their optimum designs through dispersion engineering. Among these, equiangular spiral microstrucured fiber is found to be the most promising candidate for generating an ultrawide supercontinuum in the mid-infrared region

Equiangular spiral tellurite photonic crystal fiber for supercontinuum generation in mid-infrared

We show simulations of very broad and flat Supercontinuum (SC) in both the normal and anomalous group velocity dispersion regimes of the same equiangular spiral photonic crystal fiber at low pumping powers. For the pump wavelength at 1557 nm and average pump power of 11.2 mW, we obtained a bandwidth > 3 µm (970 nm – 4100 nm) at 40 dB below the peak spectral power with fiber dispersion ~ 2.1 ps/km.nm at 1557 nm. In the same fiber, at pump wavelength 1930 nm and average pump power of 12 mW the SC bandwidth was more than 2 octaves (1300 nm – 3700 nm) and dispersion was -1.3 ps/km.nm at 1930 nm. This demonstrates the potential use of the fiber for multi-wavelength pumping with commercially available sources at fairly low power

Ultrabroad supercontinuum generation in tellurite equiangular spiral photonic crystal fiber

Simulations are presented of a very broad and flat supercontinuum (SC) in both the normal and anomalous group velocity dispersion regimes of the same equiangular spiral photonic crystal fiber at low pumping powers. For a pump wavelength at 1557 nm and average pump power of 11.2 mW, we obtained a bandwidth >3 μm (970 nm–4100 nm) at 40 dB below the peak spectral power with fiber dispersion 2.1 ps/km nm at 1557 nm. In the same fiber, at pump wavelength 1930 nm and average pump power of 12 mW the SC bandwidth was more than two octaves (1300 nm–3700 nm) and dispersion was 1.3 ps/km nm at 1930 nm. This demonstrates the potential use of the fiber for multi-wavelength pumping with commercially available sources at fairly low power

Adsorption of CO2 by Activated Carbon from Date Stones Filled into a Local Design of Automobile Exhaust

Carbon dioxide gas, CO2 with high levels in the aircreates very serious global problem linked to the climaticchanges, mostly in relation to anthropogenic emission sources.Adsorption process is among many effective techniques forremoving such gas from the air. In this study, an attempt hasbeen made to investigate the effectiveness of activated carbon(AC). obtained from easy available agricultural by-productsdates stones (DS) in capturing CO2 emissions from mobilesources, during which carbon-containing automobiles fuels areburned. AC is filled into an automobile exhaust using a glassmodel design and a stream of CO2 was supplied from cylinder.During the removal process, the effect of the AC adsorbents oncapturing CO2 was investigated using FTIR spectroscopy. Thedegree of turbidity and pH change of solutions as an affect ofcontact with CO2 were also investigated