IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Flat-gain and wide-band partial double-pass erbium co-doped fiber amplifier with hybrid gain medium
No full textA new compact wide-band hybrid optical amplifier is demonstrated using a combination of Hafnium Bismuth Erbium co-doped fiber (HB-EDF) and Zirconia-Yttria-Aluminium co-doped erbium fiber (Zr-EDF) as the gain medium. The proposed amplifier is constructed using a 1 m long HB-EDF and a 2 m long Zr-EDF in stages, in a single and a double-pass configuration, respectively. By using the right lengths of the gain fibers and a sufficient pump power, a flat gain of 17.2 dB with a gain fluctuation of less than 2.3 dB is obtained over a 55 nm bandwidth across C- and L-band wavelength regions. The noise figure is maintained below 10.6 dB within the flat gain wavelength region
Interaction of thulium fiber laser with urinary stone: effect of laser parameter on fragmented particle size and retropulsion
No full textSingle-mode thulium fiber laser (TFL) at 1.94 μm with optimal energy and pulse settings has potential benefits for lithotripsy over the presently used Ho:YAG laser. A fiber Bragg grating-based, all-fiber, continuous-wave and modulated TFL at 1.94 μm is configured to deliver up to 30 W of laser power with efficiency of 50. The TFL operating in the range of repetition rate 10 Hz-1 kHz and corresponding pulse energy 2 J-1.05 mJ is irradiated on urinary stone for in-vitro evaluation of fragmented particle size and retropulsion. TFL irradiation at higher repetition rate fragments the stones into smaller particle size (average size of few hundreds microns) resulting reduced retropulsion
Functionalized conjugated polymer with plasmonic Au nanoalloy for photocatalytic hydrogen generation under visible-NIR
No full textGold based multimetallic nanoalloys decorated on conjugated polymer nanofibers have been prepared using a greener approach without using any reducing agent. The as-prepared nanohybrids exhibited superior catalytic activity for solar hydrogen production under visible light (λ > 420 nm) irradiation and near infrared light irradiation. The UV–Visible diffuse reflectance spectra displayed strong absorption in the visible region which significantly favours the photocatalytic performance. Furthermore, the efficient charge separation suggested by electrochemical impedance measurement and photocurrent response curves for Au 50 Pt 24 Pd 26 /PPy nanohybrids which exhibited significant enhancement in H 2 generation rate compared to Au/PPy nanohybrids. The strong interface contact between Au nanoalloys and PPy nanofibers play an important role for the migration of electron during catalysis. The Mott–Schottky plot revealed that photo generated charge carrier concentration has been increased for Au 50 Pt 24 Pd 26 /PPy nanohybrids (7.93 × 10 ¹¹ cm ⁻³ ) compare to pure PPy (1.43 × 10 ¹¹ cm ⁻³ ). The present study provides a new prospect for using conducting polymer based hybrid as photocatalysts for efficient solar hydrogen production
Detection of Ammonia Gas Molecules in Aqueous Medium by Using Nanostructured Ag-Doped ZnO Thin Layer Deposited on Modified Clad Optical Fiber
Get PDFThe synthesis of Ag-doped ZnO nanorod employing hydrothermal process over modified cladd optical fiber is reported. The developed material is characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission
scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET)analysis to evaluate the morphology and the nature of nanorod formed. The initial performance of the coated modified clad optical fiber toward detection of ammonia gas in aqueous solution is also presented. The sensing performance revealed that the developed material possess improved sensitivity toward ammonia gas at room temperature compared to Ag doped nanowires containing optical fiber sensor
Self-generating Brillouin fiber laser using highly nonlinear hafnium bismuth erbium-doped fiber
No full textA compact Brillouin fiber laser (BFL) utilizing a newly developed hafnium bismuth erbium-doped fiber (HB-EDF), which functions as both the Brillouin and linear gain media, is realized in the absence of Brillouin pump. It is achieved by the self-Brillouin generation from a 0.2 m length of HB-EDF with high nonlinearity in a laser cavity. The self-generating BFL was obtained in both ring and linear laser cavities. Compared to the ring cavity, the BFL in the linear cavity produced more Brillouin stokes at a lower pump threshold. In the experiment, an eight-line comb with average spacing of 0.087 nm was generated at the HB-EDF pump power of 75.27 mW. This compact BFL has total cavity length of less than 0.5 m, and thus, this is the shortest gain medium reported for Brillouin erbium fiber laser generation without using any Brillouin pump
Suspended core microstructured optical fibers with diverse arrangements of gold-filled holes: study of the polarization characteristics and resonance strength
No full textWe study the dispersion and polarization properties as well as the coupling characteristics of suspended core microstructured optical fibers (SC-MOFs) having constant pitch and air-filling fraction with a varying suspension factor (SF) and diverse arrangements of gold-filled holes. The interaction between the core-guided fundamental mode and the surface plasmon polaritons (SPPs) generated on the surface of the gold-filled hole creates surface plasmon resonance (SPR) at the phase-matching wavelengths. It is observed that such plasmonic SC-MOF designs exhibit very high birefringence and an increased number of complete coupling points for high SF values. In addition, for all the arrangements of gold-filled holes, the coupling occurs for a higher order of the SPP for structures having greater SF. The resonance strength of such SC-MOFs is significantly enhanced and considerable reduction in full width at half maximum(FWHM) bandwidth of the SPR peak is achieved for the x-axis with suitable arrangement of gold-filled holes. The values of the coupling strength and FWHM achieved for the proposed SC-MOF structures are better compared to all the data reported until now to the best of our knowledge. The results suggest that such SC-MOF structures may be beneficial for developing polarizers or in-fiber polarization splitters with improved performance. (C) 2019 Optical Society of Americ
Solid-State Electrolytes and Electrode Materials for Fuel Cell Application
No full textDepending on the temperature of operation, there are two major types of fuel cells based on solid-state electrolytes, namely (a) solid oxide fuel cells with an operating temperature of 500-1000 degrees C, (b) polymer electrolyte membrane fuel cells with an operating temperature in the range 60-200 degrees C. For the first category, primary focus is given on the development of conventional 8 mol% yttria-stabilized zirconia (8-YSZ)-based materials along with the addition of transitional metal ion dopants that reduce the sintering temperature of the 8-YSZ making fabrication of the cells easier. Possibility of using doped ceria-based electrolyte has also been discussed briefly. Various solid-state electrodes, especially the Sr-doped lanthanum manganite, Sr-doped lanthanum ferrite, Sr-doped lanthanum cobaltite and Sr- and Co-doped barium ferrite, etc., have been reviewed both in terms of general characteristic and also the developmental activities taken up in the authors' laboratory. Similarly, solid-state anode materials, e.g. Ni-YSZ, as developed at authors' laboratory have been critically reviewed with the emphasis on the fabrication of single cell. Functionality in terms of powder synthesis and fabrication of multilayer composite anode have been discussed with electrochemical performance. The cell performance is clinically correlated with the cell microstructure. For the other category, direct alcohol fuel cells (DAFCs) technology has earned a considerable interest as one of the promising electrochemical conversion devices. However, the challenges in DAFCs arise from the need for inexpensive and durable electrocatalyst. In this regard, nanostructured Pt or Pd metal-based electrocatalysts hold the key to its advances. Nanoclusters, nanowire and nanotubes of these noble metals or their alloys have been used extensively. Some of the recent research efforts towards development of both cathode and anode electrocatalysts along with their advantages and disadvantages for low-temperature fuel cell application are highlighted