PhD students' seminar: Lisa Lopez

PhD students' seminar given by Lisa Lopez from the Lasers group, on 30 June 2022 at 1.15pm in the auditorium of the Institut d'Optique in Palaiseau, on the topic: "LED-pumped CTH:YAG luminescent concentrator as broadband incoherent source in the SWIR."

Abstract: "Lighting and imaging require light sources with high luminance. Luminescent concentrators are an alternative to laser sources for speckle-free, spectrally broadband sources with luminance higher than traditionnal incoherent sources. Based on optical pumping, luminescent concentrators increase the luminance of the pump source by one order magnitude thank to an absorption-emission process coupled with total internal reflections. So far, concentrators have been developed with Ce:YAG, for emission in yellow-orange. The purpose of this works is to transpose the concept of luminescent concentrator into the Short Wavlelength Infrared (SWIR) by using other luminescent crystals.
We have demonstrated an incoherent source centred at 2100nm with a bandwidth of 300nm. It spectral brightness is an order of magnitude higher than a black body at 1500k and that LEDs emitting in this bandwith. This source consists of a cascade of luminescent concentrators with a Ce:YAG pumped by blue LEDs in first and a CTH:YAG (CTH:chromium-thulium-holmium) in second. It has a potential for alternative SWIR sources with applications like active imaging."