Sellmeier dispersion for phase-matched terahertz generation in ZnGeP2

A Sellmeier dispersion of zinc germanium diphosphide (ZnGeP2) crystal has been formulated to determine the phase-matching characteristics of the crystal for the generation of coherent tunable terahertz radiation by difference-frequency mixing techniques. The results computed with the formulated Sellmeier dispersion provide an excellent fit to the experimental data.     

Linear and nonlinear optical properties of ZnGeP2 crystal for infrared laser device applications: revisited

Measurement of refractive indices in the spectral bands 9-11 microm and 1.32 microm from a cw CO2 laser and a Q-switched Nd:YAG laser, respectively, is reported in a ZnGeP2 crystal. A new set of Sellmeier dispersion relations has been derived from the measured refractive indices data in this crystal. Second-harmonic generation (SHG) of CO2 laser radiation in this crystal is also reported. It is also seen that the previously reported phase-matching data for others experiments in SHG and optical parametric devices is explained satisfactorily with this new set of Sellmeier dispersion relation.     

Coal washing scenario in India and future prospects

International Journal of Coal Science & Technology - Coal Washing Exploration in India dates back to 1900s; though, first coking coal washeries in India were installed after independence. At...     

Development of a framework for sustainable improvement in performance of coal mining operations

Clean Technologies and Environmental Policy - India is a developing country, where boosting of modern energy supply is the primary requirement for economic growth. About two-thirds of this energy...     

Flexible and free-standing films containing cobalt-doped nanocrystalline zinc oxide dispersed in polyvinylidene fluoride matrix: synthesis and characterization

Polymer Bulletin - Synthesis of free-standing flexible Co-ZnO/PVDF composite films is realized by sol–gel technique. Modulation of the optical and microstructural properties of the above...     

Designing a green optical network unit using ARMA-based traffic prediction for quality of service-aware traffic

The optical access networks (OANs) provide an attractive solution to the bandwidth bottleneck problem of the last mile. However, it has been proved (Baliga et al. in J Lightwave Technol 27(13):2391–2403, 2009; Baliga et al. in IEEE Commun Mag 49(6):70–77, 2011) that the OAN consumes a significant ratio of the total energy consumed in an optical networking scenario. This has provided incentive for inspection of energy-efficient schemes for OANs. It has been demonstrated in the literature that energy consumption figures of an OAN can be improved by either designing efficient hardware or employing better media access control (MAC) protocols. In this paper, we design a MAC protocol for OANs to ensure energy-efficiency in the presence of quality of service (QoS)-aware traffic. The proposed scheme incorporates traffic prediction-based selection of different sleep (energy-efficient) modes of operation, of the optical network units—ONUs (OAN end units). It also implements switching between different sleep modes to maintain high QoS with significant energy-efficiency figures. The discussed scheme requires processing at the ONU only and can work independent of the entire OAN (ONU assisted). Thus, our proposal is an attractive solution for the already deployed networks or even in green field deployment.     

Synthesis of carbon nano-fibers on p-Si having improved temperature sensing capability

Synthesis of an innovative material for temperature sensor based on carbon nano-fibers (CNFs) on p-Si substrates has been demonstrated. The CNF films were characterized by SEM, Raman and FTIR studies. First order Raman spectra indicated a G band at ～1597 cm^?1 corresponding to the E_2g tangential stretching mode of an ordered graphitic structure with sp² hybridization and a D band located ～1350 cm^?1 originated from disordered carbon. Gold fingers were deposited on the p-Si/CNF surface for resistance measurement. Temperature sensing properties were also investigated critically. Resistance changes with temperature (ΔR/R) in p-Si/CNF films are found to be significantly large 30–60% Very stable, reproducible and improved temperature sensing properties would make this material superior to commonly available temperature sensors.     

Room Temperature Magnetism in Free-Standing Nano-Ni/PVDF Composites

Nanocrystalline Ni was incorporated in polyvinylidene fluoride (PVDF) in three different proportions to obtain free-standing flexible film by sol-gel technique. Effect of nano-Ni loading in the PVDF matrix on the optical, microstructural, and magnetic properties of the nano-Ni/PVDF composite material was studied. Variation of magnetic moments with magnetic field at different temperatures was recorded in the composite-free-standing films. X-ray photoelectron spectroscopy studies indicated that incorporated Ni was in Ni²⁺ and Ni⁴⁺ states. Ni²⁺ atomic concentration was found to be significantly larger than Ni⁴⁺ concentration in all the samples suggesting Ni²⁺ in the PVDF lattice are responsible for observed room temperature ferromagnetism.