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F J Lubken - One of the best experts on this subject based on the ideXlab platform.
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diode pumped q switched alexandrite laser in single longitudinal Mode Operation with watt level output power
Optics Letters, 2018Co-Authors: Alexander Munk, Michael Strotkamp, H D Hoffmann, Bernd Jungbluth, Reinhart Poprawe, J Hoffner, Martin Walochnik, Martin Traub, F J LubkenAbstract:We present significantly improved performance data of a diode-pumped Q-switched Alexandrite laser in single longitudinal Mode Operation developed as a beam source for resonance lidar systems. The average output power of the laser—operating at the potassium resonance at 770 nm with a linewidth below 10 MHz—could be increased by a factor of five to the Watt-level by means of an optimized resonator design and pump scheme. The pulse energy is 1.7 mJ with a beam quality of M2≤1.1 in both spatial directions at a repetition rate of 500 Hz.
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diode pumped alexandrite ring laser in single longitudinal Mode Operation for atmospheric lidar measurements
Optics Express, 2018Co-Authors: Alexander Munk, Michael Strotkamp, H D Hoffmann, Bernd Jungbluth, Reinhart Poprawe, J Hoffner, F J LubkenAbstract:: We present, to the best of our knowledge, design and performance data of the first diode-pumped Alexandrite ring laser in Q-switched single-longitudinal Mode (SLM) Operation. The laser resonator contains two Alexandrite crystals, which are pumped longitudinally by means of two laser diode-bar modules emitting at 636 nm. Single-longitudinal Mode Operation is achieved by seeding the laser with a diode laser operating in SLM and actively stabilizing the cavity, yielding a linewidth of < 10 MHz at the potassium resonance line at 770 nm. The pulse energy is 1 mJ at a repetition rate of 150 Hz and 0.65 mJ at 320 Hz. The beam quality of M2 < 1.2 in both directions remains unchanged for the different repetition rates. After characterization in the laboratory, the laser was implemented in a novel mobile lidar system and first atmospheric measurements were conducted successfully.
Venkata S Mohan - One of the best experts on this subject based on the ideXlab platform.
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induction of anoxic microenvironment in multi phase metabolic shift strategy during periodic discontinuous batch Mode Operation enhances treatment of azo dye wastewater
Bioresource Technology, 2014Co-Authors: Nagendranatha C Reddy, Naresh A Kumar, Annie J Modestra, Venkata S MohanAbstract:Abstract Variation in anoxic microenvironment (multi-phase (MP) metabolic shift strategy) during cycle Operation of periodic discontinuous batch/sequencing batch (PDBR/SBR) Mode Operation showed enhanced degradation of recalcitrant azo dye (C.I. Acid Black 10B) at higher dye load (1250 mg/l). The process performance was evaluated by varying anoxic phasing period during cycle Operation. Before multiphase (BMP) Operation with 2.1% of anoxic period showed color/COD removal efficiency of 41.9%/46.3%. Increment in anoxic period responded favorable in enhancing treatment efficiency [AMPI (16.2%), 49.4%/52.4%; AMPII (26.6%), 54.7%/57.2%; AMPIII (34.9%), 58.4%/61.5%]. Relatively higher bio-electrochemical activity, persistent reductive behavior (redox catalytic currents, 0.26/−0.72 μA), prevalence of redox shuttlers (Fe–S proteins, cytochromes, quinones) facilitating enhanced electron transfer by minimization of associated losses and higher enzyme activities were observed with induction of anoxic phase. Anoxic condition shifts system microenvironment between oxidation and reduction assisting reduction of dye to its intermediates followed by their mineralization.
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relative performance of biofilm configuration over suspended growth Operation on azo dye based wastewater treatment in periodic discontinuous batch Mode Operation
Bioresource Technology, 2013Co-Authors: Venkata S Mohan, Nagendranatha C Reddy, Naresh A Kumar, Annie J ModestraAbstract:Functional role of biofilm and suspended growth bioreactor configurations in response to the treatment of azo-dye (C.I. Acid Black 10B) bearing wastewater was evaluated in periodic discontinuous batch Mode Operation at varying dye concentrations. The biofilm system depicted higher dye removal efficiency (93.14%) compared to suspended Mode (84.29%) at 350 mg dye/l Operation. Both the reactor configurations did not show much process inhibition at higher dye loads studied. Azo reductase and dehydrogenase enzyme activities showed significant variation indicating the different metabolic capabilities of the native-microflora, stable proton shuttling between metabolic intermediates and differences in the delivery of reducing powers from the substrate metabolism towards dye removal. Voltammograms visualized marked variations in electron discharge properties with the function of reactor configuration, time intervals and dye load. Higher redox catalytic currents, lower Tafel slopes and polarization resistance showed good correlation with enzyme activities and dye removal.
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azo dye remediation in periodic discontinuous batch Mode Operation evaluation of metabolic shifts of the biocatalyst under aerobic anaerobic and anoxic conditions
Separation and Purification Technology, 2013Co-Authors: Venkata S Mohan, Suresh P Babu, S SrikanthAbstract:Abstract Shifts in microbial metabolism with the function of aerobic, anaerobic and anoxic microenvironments were evaluated in periodic discontinuous batch Mode Operation in response to the treatment of azo dye (C.I.Acid Black 10B) bearing wastewater. Anoxic Operation depicted higher dye removal efficiency (95.18%) followed by anaerobic (93.67%) and aerobic (68.77%) Operations. Switching between aerobic and anaerobic metabolic functions during anoxic Operation facilitated the reduction of dye to its intermediates (anaerobic) followed by their mineralization (aerobic). Function of dye as a terminal electron acceptor (TEA) along with the limited oxygen available might be the reason for the observed higher dye removal under anoxic Operation. Azo reductase activity showed marginal variation with the function of anoxic and anaerobic conditions indicating the similar capabilities of the biocatalyst. However, dehydrogenase activity showed significant variation with the function of operating microenvironment indicating the differences in the delivery of reducing powers from the substrate metabolism towards dye removal. The bio-electro kinetics showed well correlation with the redox reactions, enzyme activities and dye removal. Microbial inventory analysis documented the involvement of organisms with anaerobic and facultative metabolic functions having heterotrophic and autotrophic nutrition Modes. Aerobic Operation documented the dominance of facultative (83%) followed by obligative aerobic (17%) bacteria while anoxic and anaerobic Operations facilitated the distribution of facultative (67% and 83%, respectively) and obligative anaerobic (33% and 17%, respectively) bacteria.
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simulated acid azo dye acid black 210 wastewater treatment by periodic discontinuous batch Mode Operation under anoxic aerobic anoxic microenvironment conditions
Ecological Engineering, 2007Co-Authors: Venkata S Mohan, Chandrasekhara N Rao, P N SarmaAbstract:Abstract Treatment of simulated acid azo dye (C.I. Acid black 210) wastewater was studied in periodic discontinuous batch Mode Operation employing sequencing batch reactor (SBR) with suspended growth configuration under anoxic–aerobic–anoxic microenvironment. The performance of the reactor was evaluated at two organic loading rates (0.56 kg COD/m 3 -day and 0.75 kg COD/m 3 -day) with a total cycle period of 24 h [fill phase: 30 min; react phase: 23 h; settle phase: 15 min; decant phase: 15 min] at room temperature. The performance of SBR was assessed by monitoring both COD and colour (OD-617 nm) concentrations. Periodic discontinuous batch Mode Operation feasibility for dye colour removal along with simultaneous substrate (COD) removal. The performance efficiency of the system was found to depend on the operating organic loading rate. Induced anoxic microenvironment during cycle Operation and persistent anoxic microenvironment in the internal layer of suspended biomass may be probable reasons for dye mineralization/reduction. Rapid startup period and non-inhibited performance at higher loading rate are some of the advantages observed in the SBR Operation.
Alexander Munk - One of the best experts on this subject based on the ideXlab platform.
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diode pumped q switched alexandrite laser in single longitudinal Mode Operation with watt level output power
Optics Letters, 2018Co-Authors: Alexander Munk, Michael Strotkamp, H D Hoffmann, Bernd Jungbluth, Reinhart Poprawe, J Hoffner, Martin Walochnik, Martin Traub, F J LubkenAbstract:We present significantly improved performance data of a diode-pumped Q-switched Alexandrite laser in single longitudinal Mode Operation developed as a beam source for resonance lidar systems. The average output power of the laser—operating at the potassium resonance at 770 nm with a linewidth below 10 MHz—could be increased by a factor of five to the Watt-level by means of an optimized resonator design and pump scheme. The pulse energy is 1.7 mJ with a beam quality of M2≤1.1 in both spatial directions at a repetition rate of 500 Hz.
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diode pumped alexandrite ring laser in single longitudinal Mode Operation for atmospheric lidar measurements
Optics Express, 2018Co-Authors: Alexander Munk, Michael Strotkamp, H D Hoffmann, Bernd Jungbluth, Reinhart Poprawe, J Hoffner, F J LubkenAbstract:: We present, to the best of our knowledge, design and performance data of the first diode-pumped Alexandrite ring laser in Q-switched single-longitudinal Mode (SLM) Operation. The laser resonator contains two Alexandrite crystals, which are pumped longitudinally by means of two laser diode-bar modules emitting at 636 nm. Single-longitudinal Mode Operation is achieved by seeding the laser with a diode laser operating in SLM and actively stabilizing the cavity, yielding a linewidth of < 10 MHz at the potassium resonance line at 770 nm. The pulse energy is 1 mJ at a repetition rate of 150 Hz and 0.65 mJ at 320 Hz. The beam quality of M2 < 1.2 in both directions remains unchanged for the different repetition rates. After characterization in the laboratory, the laser was implemented in a novel mobile lidar system and first atmospheric measurements were conducted successfully.
L Goldberg - One of the best experts on this subject based on the ideXlab platform.
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single Mode Operation of a coiled multiMode fiber amplifier
Optics Letters, 2000Co-Authors: Jeffrey P Koplow, Dahv A V Kliner, L GoldbergAbstract:The authors report a new approach to obtain single-transverse-Mode Operation of a multiMode fiber amplifier, in which the gain fiber is coiled to induce significant bend loss for all but the lowest-order Mode. They have demonstrated this method by constructing a coiled amplifier using Yb-doped, double-clad fiber with a core diameter of 25 {micro}m and NA of {minus}0.1 (V {approx} 7.4). When operated as an ASE source, the output beam had an M{sup 2} value of 1.09 {+-} 0.09; when seeded at 1,064 nm, the slope efficiency was similar to that of an uncoiled amplifier. This technique does not require exotic fiber designs or increase system complexity and is inexpensive to implement. It will allow scaling of pulsed fiber lasers and amplifiers to significantly higher pulse energies and peak powers and cw fiber sources to higher average powers while maintaining excellent beam quality.
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single Mode Operation of a coiled multiMode fiber amplifier
Optics Letters, 2000Co-Authors: Jeffrey P Koplow, Dahv A V Kliner, L GoldbergAbstract:The authors report a new approach to obtain single-transverse-Mode Operation of a multiMode fiber amplifier, in which the gain fiber is coiled to induce significant bend loss for all but the lowest-order Mode. They have demonstrated this method by constructing a coiled amplifier using Yb-doped, double-clad fiber with a core diameter of 25 {micro}m and NA of {minus}0.1 (V {approx} 7.4). When operated as an ASE source, the output beam had an M{sup 2} value of 1.09 {+-} 0.09; when seeded at 1,064 nm, the slope efficiency was similar to that of an uncoiled amplifier. This technique does not require exotic fiber designs or increase system complexity and is inexpensive to implement. It will allow scaling of pulsed fiber lasers and amplifiers to significantly higher pulse energies and peak powers and cw fiber sources to higher average powers while maintaining excellent beam quality.
M J Damzen - One of the best experts on this subject based on the ideXlab platform.
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nonastigmatic alexandrite ring laser design with wavelength tunable single longitudinal Mode Operation
Journal of The Optical Society of America B-optical Physics, 2020Co-Authors: Juna Sathian, Goronwy Tawy, A Minassian, Xin Sheng, M J DamzenAbstract:This work presents a study of a fully nonastigmatic design of a single-longitudinal-Mode, wavelength-tunable, unidirectional alexandrite ring laser cavity and assessment of its performance compared to more complex laser design requiring astigmatism compensation. A “displaced Mode” nonastigmatic laser cavity design eliminating astigmatic cavity elements is developed around an alexandrite crystal end-pumped by a low-brightness, high-power red diode laser pump system. Single-longitudinal-Mode, continuous-wave Operation is demonstrated with output power of 700 mW with an excellent TEM00 Mode (M2<1.1) across a wide pump power range. Wavelength tuning from 748–773 nm is produced using a birefringent filter plate. The nonastigmatic alexandrite laser design achieves better spatial quality and resilience to maintain TEM00 Operation across wide variation in pump-induced lensing compared to the astigmatic design. To the best of our knowledge, this is the first wavelength-tunable, single-longitudinal-Mode Operation of a unidirectional alexandrite ring system in a fully nonastigmatic cavity regime.
