LED pumped polymer laser sensor for explosives

The authors would like to acknowledge financial support for this research from the EPSRC HYPIX project (grant number EP/ F059922/1 and EP/F05999X/1), and the TIRAMISU project, funded by the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 284747.A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light-emitting diode. The laser shows a two-stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The 'double-threshold' phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface-emitted output under optimized LED excitation. A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light-emitting diode. The laser shows a two-stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The 'double-threshold' phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface-emitted output under optimized LED excitation.Publisher PDFPeer reviewe

Equitable and Holistic Public Health Measures During the Singaporean COVID-19 Pandemic

This Covid-19 pandemic has been a trying time for all countries, governments, societies, and individuals. The physical, social, and organizational infrastructure of healthcare systems across the world is being stressed. This pandemic has highlighted that the healthcare of the country is as strong as its weakest link and that no aspect of life, be it social or economic, is spared from this pandemic. The authors would like to highlight some of the lessons learned from Singapore’s management of the Covid-19 pandemic. During the Singaporean Covid-19 pandemic, public health policy planning was all encompassing in its coverage, involving various stakeholders in government and society. The important role of individuals, governments, industry, and primary healthcare practitioners when tackling COVID-19 are highlighted. Singapore’s management of the Covid-19 pandemic involved an approach that involved the whole of society, with a particular focus on supporting the vulnerable foreign worker population, which formed the majority of Covid-19 cases in the country. Hopefully amidst the trying times, valuable lessons are learnt that will be etched into medical history and collective memory. We hope to highlight these lessons for future generations, both for members of the public and fellow healthcare practitioners