Publications by authors named "Saumyabrata Banerjee"
Article Synopsis
- Researchers successfully amplified 10 ns pulses up to 10 J energy at a rate of 10 Hz using a DiPOLE laser amplifier with innovative Yb:YAG/Cr:YAG composite slabs made via adhesive-free bonding (AFB) technology.
- The bonded slabs demonstrate effective performance in high energy cryogenic laser amplifiers and allow for efficient frequency doubling, achieving 3.9 J in the green spectrum from a 5 J infrared output with a 78% conversion efficiency.
- The study highlights AFB technology’s potential to produce larger gain material slabs, addressing current manufacturing limits and facilitating energy scaling in high-energy lasers where traditional methods fall short.*
A new approach to generation of a burst of high-energy green pulses by placing a high-energy multi-slab Yb:YAG DPSSL amplifier and SHG crystal inside a regenerative cavity is presented. In a proof-of-concept test, stable generation of a burst of six green (515 nm) pulses, each 10 ns in duration and separated by 29.4 ns (34 MHz), with 2.
View Article and Find Full Text PDFWe report on laser shock peening (LSP) of tungsten, a material used as a divertor in Tokamak machine for magnetic confinement fusion reactions such as the ITER facility (France) and JET facility (UK). Peak compressive stresses of -370 MPa and depths of up to 1.75 mm were recorded when 0.
View Article and Find Full Text PDFTraditionally, nanosecond laser shock peening (ns-LSP) of metals requires an additional application of an absorption layer (black paint) and more importantly a confinement layer (typically water or transparent material) on the workpiece for introduction of compressive stresses. In this paper, we demonstrate for the first time, to the best of our knowledge, introduction of compressive stresses in pure tungsten and its alloy TAM7525 (75% tungsten and 25% copper) without any absorption and confinement layer for ns-LSP. Peak compressive stresses of -349 MPa and -357 MPa were measured in pure tungsten and TAM7525, respectively, when a 0.
View Article and Find Full Text PDFWe report on obtaining output energy of 146 J in 10 ns long pulses at 10 Hz repetition rate from Bivoj, a multi-Joule multi-slab cryogenic gas-cooled diode pumped solid state laser, by overcoming its damage threshold bottleneck. This is a 40% energy and power increase of the laser system in comparison to our previous publication and to the most powerful multi-Joule high power laser system.
View Article and Find Full Text PDFWe report on the successful demonstration of second and third harmonic conversion of a high pulse energy, high average power 1030 nm diode pumped Yb-doped yttrium aluminum garnet (Yb:YAG) nanosecond pulsed laser in a large aperture lithium triborate (LBO) crystal. We demonstrated generation of 59.7 J at 10 Hz (597 W) at 515 nm (second harmonic) and of 65.
View Article and Find Full Text PDFArticle Synopsis
- The paper introduces a model that predicts how thermal stress affects birefringence in high energy, high repetition rate Yb:YAG lasers by analyzing factors like geometry, pump power, and cooling parameters.
- Experimental results from a DiPOLE 100 J, 10 Hz laser amplifier show that the model's predictions align well with what was observed.
- The study highlights that the level of depolarisation—ranging from 5% to 40%—is influenced by the input polarisation state, suggesting that using waveplates in multipass amplifiers can significantly minimize depolarisation losses.
We report on frequency doubling of high-energy, high-repetition-rate ns pulses from a cryogenically gas cooled, multi-slab Yb:YAG laser system, using a type-I phase-matched lithium triborate (LBO) crystal. Pulse energy of 4.3 J was extracted at 515 nm for a fundamental input of 5.
View Article and Find Full Text PDFArticle Synopsis
- This report investigates type-I phase-matched second harmonic generation (SHG) using DKDP, YCOB, and LBO crystals with a Yb:YAG laser operating at 1029.5 nm.
- DKDP showed a 45% efficiency, while YCOB and LBO achieved higher efficiencies of 50% and 65% respectively at the same fundamental intensity.
- LBO demonstrated the highest conversion efficiency of 82% at increased intensity, generating 5.6 J of output energy, while YCOB did not improve at this intensity; the report also includes theoretical temperature maps for potential higher energy operation.
We report on the successful demonstration of a 100 J-level, diode pumped solid state laser based on cryogenic gas cooled, multi-slab ceramic Yb:YAG amplifier technology. When operated at 175 K, the system delivered a pulse energy of 107 J at a 1 Hz repetition rate and 10 ns pulse duration, pumped by 506 J of diode energy at 940 nm, corresponding to an optical-to-optical efficiency of 21%. To the best of our knowledge, this represents the highest energy obtained from a nanosecond pulsed diode pumped solid state laser.
View Article and Find Full Text PDFThe Diode Pumped Optical Laser for Experiments (DiPOLE) project at the Central Laser Facility aims to develop a scalable, efficient high pulse energy diode pumped laser amplifier system based on cryogenic gas cooled, multi-slab ceramic Yb:YAG technology. We present recent results obtained from a scaled down prototype laser system designed for operation at 10 Hz pulse repetition rate. At 140 K, the system generated 10.
View Article and Find Full Text PDFTemperature dependent absorption and emission cross-sections of 5 at% Yb(3+) doped yttrium lanthanum oxide (Yb:YLO) ceramic between 80K and 300 K are presented. In addition, we report on the first demonstration of ns pulse amplification in Yb:YLO ceramic. A pulse energy of 102 mJ was extracted from a multi-pass amplifier setup.
View Article and Find Full Text PDFWe report on the first demonstration of a diode-pumped, gas cooled, cryogenic multislab Yb:YAG amplifier. The performance was characterized over a temperature range from 88 to 175 K. A maximum small-signal single-pass longitudinal gain of 11.
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