Madhab Pokhrel

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Using the integrating sphere technique the absolute quantum yield measurements of the visible emission bands at 550, 650 and 750 nm in Yb/Ho doped M2O2S (M1⁄4Y, Gd, La) upconversion phosphor have been reported for the first time. Observations show that the 750 nm emission in La2O2S doped with 1 mol% each of Yb and Ho yield the highest efficiency of 0.12%(More)
There is increasing interest in rare earth (RE) doped nanoparticles (NPs) due to their sharp absorption and photoluminescence (PL) in the near infrared (NIR) spectral region. These NIR based nanoparticles (NPs) could allow biological imaging at substantial depths with enhanced contrast and high spatial resolution due to the absence of auto fluorescence in(More)
In this letter, we report the absolute upconversion quantum yields (QY) for 9% Yb3þ and 1% Er3þ codoped La2O2S and its comparison with NaYF4 doped with 20% Yb 3þ , 2% Er3þ for all the upconversion emissions centered at 410, 550, 667, and 822 nm at various excitation power densities at 977 nm excitation. The maximum upconversion QY for 9% Yb3þ and 1% Er3þ(More)
Highly transparent Tm:Ho:YAG transparent ceramics were prepared using advanced ceramic technology and their spectroscopic properties were studied for infrared laser applications. Following the Judd-Ofelt procedure several spectroscopic properties such as the radiative transition probability (Arad), radiative decay time ( rad) and fluorescence branching(More)
Department of Physics and Astronomy, U Antonio, Texas 78249, USA. E-mail: ekf012@ Department of Biomedical Engineering, Uni Circle, San Antonio, Texas 78249, USA † Electronic supplementary information setup, TEM images showing defects, calculation using the comparison meth viability and cytotoxicity, absorption spe cross-section table for the excitation(More)
Spectroscopic studies of Er3þ/Yb3þ co-doped (Ba,La)-fluorotellurite glass composition have been carried out using standard experimental and theoretical methods. Quantitative analyses of the room temperature absorption and emission spectra as well as the emission lifetimes yield various important spectroscopic parameters such as the radiative decay rates,(More)
In this article, we report the detailed spectroscopic studies of high Ercontent (50%) transparent YAG ceramic co-doped with nominal Cr content (0.1 mol %). Various radiative and non-radiative spectroscopic properties such as radiative decay time, fluorescence branching ratio, emission/absorption cross sections, internal radiative quantum yields of the(More)
Optical damage experiments were carried out in a series of Holmium doped congruent lithium niobate (Ho:cLN) crystals as a function of dopant concentration and laser intensity. The light induced beam distortion was recorded with a camera and a detector under the pseudo-Z-scan configuration. At 532 nm, strong suppression of the optical damage was observed for(More)
Polycaprolactone (PCL) fibers were produced using Forcespinning® (FS). The effects of PCL concentration, solvent mixture, and the spinneret rotational speed on fiber formation were evaluated. The concentration of the polymer in the solvents was a critical determinant of the solution viscosity. Lower PCL concentrations resulted in low solution viscosities(More)