Department of Electrical and Electronics Engineering
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Item Modal Characteristics of a doubly clad step- index optical fiber- general analytical approach(Canadian Science Publishing, 1988) Chaubey, V.K.Using a fairly rigorous approach, a general characteristic equation for a doubly clad step-index fibre has been derived under the assumption that the refractive-index difference between the inner and outer cladding is small. Two different profiles, i.e., the W profile and the staircase profile, have been treated together and a discussion of their common characteristics has been made. Cutoff conditions for low-order modes have been obtained. For a certain range of values of the transverse-phase parameter ratio, the singly-clad fibre has greater mode cutoff V numbers than those of a doubly clad fibre. The analysis anticipates the possibility of obtaining greater cutoff V numbers for W-profile fibres.Item Modal attenuation in a four-layer metal-clad planar waveguide with a semi-parabolically graded guiding layer — an analytical study(Elsevier, 1991-04) Chaubey, V.K.A general characteristic equation is derived for a four-layer metal-clad graded-index slab waveguide with a guiding layer having a semi-parabolic refractive index profile. The attenuation parameter for the lowest-order TE and TM modes are computed and the results are presented and compared with those obtained by Al-Bader and Jamid for the three-layer case. We make similar calculations for a waveguide with a step-index guiding layer. The attenuation is found to be less sensitive to a change of the guiding layer width in the case of the four-layered structure with a parabolically graded guiding layer than it is for the corresponding three-layered structure. This situation is reversed in the case of a step-index waveguide. Thus the proposed four-layer planar waveguide shows some polarization discrimination properties which are significantly different from those of the three-layer waveguide.Item Field Intensity and Power Confinement of Four-layer Slab Waveguides with Various Refractive Index Profiles in the Guiding Region(De Gruyter, 1994) Chaubey, V.K.Relative field intensity distributions in three differenttypes of structures, i.e. Step index Slab Waveguide(SSW), Semi-parabolic index Slab Waveguide (SPSW)and Parabolic index Slab Waveguide (PSW) have beenanalytically derived and computed. It is found that thefield in the guiding region is maximum in case of thePSW structure. Analytical expressions for the relativepower confinement factors have also been obtained.The applicability of these results in the estimation ofcoupling coefficient of some of the Distributed FeedBack (DFB) lasers have also been briefly shown.Item Frequency filtering in diffused optical planar waveguides(NISCAIR, 1999-03) Chaubey, V.K.Diffusion techniques have provided as alternative to thin-films technology for the fabrication of planar optical waveguides in CdS, ZnSe, LiNbO3, and LiTaO3 etc.