Diode-pumped ultrafast Yb:KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking

A high-power sub-60 fs mode-locked diode-pumped Yb:KGW laser based on hybrid action of an InGaAs quantum-dot saturable absorber mirror and Kerr-lens mode locking was demonstrated. The laser delivered 56 fs pulses with 1.95 W of average power corresponding to 450 kW of peak power. The width of the generated laser spectrum was 20.5 nm, which was near the gain bandwidth limit of the Yb:KGW crystal. To the best of our knowledge, these are the shortest pulses generated from the monoclinic double tungstate crystals (and Yb:KGW laser crystal in particular) and the most powerful in the sub-60 fs regime. At the same time, they are also the shortest pulses produced to date with the help of a quantum-dot-based saturable absorber. High-power operation with a pulse duration of 90 fs and 2.85 W of average output power was also demonstrated

Preparation of useful raw materials from Refinery sludge and its utilisation in rubber processing

Petroleum, a mixture of organic compounds, comes from underground rock formations ranging in age from ten to several hundred million years. The process by which it is formed and developed is not yet completely known. Studies indicate that petroleum is formed mainly from microscopic-sized marine animals and plants. When these organisms died in water of low oxygen content, they did not decompose. Thus their remains sank to the bottom to be buried under accumulations of sediment. Their conversion to petroleum remains a subject of research even today.Cochin University of Science and TechnologyDepartment of Polymer Science and Rubber Technology, Cochin University of Science and Technolog

Evaluation of the characteristics of nano hybrid composite resin modified with graphene after thermomechanical loading cycle

To evaluate the characteristics of a thermomechanically loaded composite resin enhanced with graphene nanoparticles. A total of 60 specimens were manufactured with Test group TG1 (20), TG2 (20), and control group CG (20). All samples were subjected to surface roughness using a three-dimensional (3D) Optical profilometer and flexural strength. All specimens were subjected to thermomechanical cyclic loading. Microhardness measurement was performed with a microhardness tester. The average microhardness and flexural strength were higher in test groups TG1 and TG2 and lowest in control group CG. There was an improvement in surface roughness, flexural strength, and microhardness in the test group after the addition of graphene nanoparticles compared to the control group. Conclusion: The addition of graphene nanoparticles to composite resin significantly improved flexural strength and microhardness. The physical and chemical properties of the composite showed marked improvement