Department of Electrical, Electronic and Communication Engineering (EECE)

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    Comparative Study of Dispersion and Other Losses including Nonlinear Impairments of Different Models of Photonic Crystal Fiber (PCF) by Varying Geometrical Shapes
    (Department of Electrical, Electronic and Communication Engineering, 2017-12) Prottasha, Soheli Noshin; Ahmed, Neti Nowrin Nilma; Afroj, Jinia
    This thesis paper presents detail analysis of a hexagonal, octagonal, decagonal and hybrid shaped photonic crystal fiber (PCF) with an aim to compare their performance over various parameters of communication. Deliberate study on the constructional design of the PCF models is carried out to find the optical signal guidance mechanisms through it. The COMSOL Multi-Physics 4.4 Simulation Software is used to perform the modal analysis of the designed PCFs. Three conventional PCFs such as H-PCF, O-PCF and D-PCF are constructed with four layered circular air hole rings. The hybrid structure (Hy-PCF) is also made of four air hole rings but consists of elliptical and square air holes along with the circular ones. Pure silica material is used as core-cladding materials. All the properties are analyzed for 0.80-2.00μm wavelengths range. The dispersion profile of the H-PCF is found quite varying whereas the O-PCF and D-PCF have shown zero to negative dispersion with little variation. At 1.55 μm wavelengths, the calculated dispersion for H-PCF, O-PCF and D-PCF are −2.80 ps/nm-km, −8.61 ps/nm-km and−11 ps/nm-km respectively. The Hy-PCF has exhibited more negative dispersion with almost linearly decreasing characteristics against wavelengths. The value is −81.08 ps/nm-km for 1.55 μm wavelengths. A very negligible confinement loss is obtained for H-PCF, O-PCF and D-PCF for a large wavelengths range. At 1.55 μm wavelengths the H-PCF, O-PCF, D-PCF and Hy-PCF have provided 25.42 μm2, 19.83 μm2, 15.7 μm2 and 5.15 μm2effective mode areas respectively. For the three conventional structures of similar parameters the values of nonlinear coefficient are found close to each other (3.43W-1km-1, 2.865W-1km-1 and 2.493 W-1km-1 respectively at 1.55 μm) but the Hy-PCF has shown 19.03W-1km-1. Moreover the conventional PCFs have provided negligible birefringence of the order of 10-6 only, but the Hy-PCF has provided large birefringence (4.34×10−3 at 1.55 μm wavelengths). Considering the overall system performance, it can be said that, this findings of this thesis on PCF structures will help to fabricate better kind of optical transmission media of more data rates. Loss parameter analysis of all structures studied will suggest their application in specific areas of optical communication.