Nandam Ashok

Long-period-grating in a trench assisted planar optical waveguide

We present long-period-grating in a planar optical waveguide that contains a low-index trench in the cladding region. The effect of the trench on transmission spectrum of the grating has been studied. The waveguide structure has been analyzed by the transfer matrix method and the output spectrum of the grating has been calculated by the coupled mode theory. Our numerical results show that position, strength, and width of the trench significantly affect the transmission spectrum of the grating. In particular, we show the appearance of triple resonance between a set of coupled modes and obtain an ultrawide band rejection in the output spectrum. We numerically demonstrate applications of the proposed structure in wideband rejection filters, refractive index sensors, and gain equalization of erbium-doped waveguide amplifiers.

Dual-Core Leaky Waveguide-Based Filters for Erbium-Doped Waveguide Amplifier

Abstract This article gives the design of a gain-flattening filter for an erbium-doped waveguide amplifier using a dual-core resonant leaky waveguide. The spectral variation of leakage loss of the waveguide has been used for gain equalization of the erbium-doped waveguide amplifier in the conventional (C) band. Leakage loss of the structure has been calculated by using the transfer matrix method. Numerical simulation results show a 17.5-dB gain with a gain excursion of ±1.35 dB in the C-band (1,526 nm–1,566 nm) of a typical erbium-doped waveguide amplifier. The study should be useful in designing integrated optic gain-flattening filters.

PEM in Relation to Birth Order and Birth Interval in Children Aged 1–6 Years in Urban Slums of Mysore City

An indirect source of disease transmission is contaminated dental casts. To disinfect dental cast number of methods are employed. Spraying a disinfectant looks more handy and convenient method of disinfecting the cast. However in the process some mechanical properties of the material of the cast may be affected that are not desired. In this study three commercially available spray disinfectant namely-Iodophor, Unidex and Lysol were used to see their effect on the compressive strength of Type III (dental stone) gypsum product. The results were compared and statistically analyzed by one way analysis of Variance and Bonferroni test. It was found that Unidex (2.09% Acid glutarladehyde) affected the compressive strength of the Type III (dental stone) gypsum product in terms of significantly decreasing the strength. Though other two spray disinfectants also affected the compressive strength but Iodophor (1.64% available iodine) caused statistically non significant decrease and Lysol (cresol with soap solution) caused non significant increase in the compressive strength.