LED pumped tunable lasers and applications in the UV range – ALEDxandrite
The unprecedented development of visible Electro Luminescent Diodes (LEDs) observed in the last few years opens new opportunities for pumping tunable solid-states lasers emitting in the very near infrared (700-900 nm). Indeed, the lack of high-power pump sources in the visible -where these lasers have to be pumped-, strongly limits the development of these sources.
In this frame, two crystals have an interesting potential for LED pumping : Alexandrite (Cr3+:BeAl2O4) tunable between 700 nm and 800 nm and Cr:LiSAF (Cr3+:LiSrAlF6), tunable between 800 nm et 950 nm.
The project "ALEDxandrite" aims at demonstrating the first LED pumping with these crystals targeting applications using tunable light in the near infrared and in the ultra-violet using harmonic generation:
Military applications include detection of improvised explosive devices (IED). Alexandrite and Cr:LiSAF can address the range of interest (280 nm-360 nm) by frequency conversion in two or three conversion stages starting from the LED pumping. To date this then represents the simplest way to address the requirements of remote sensing.
Civil applications are already numerous for alexandrite, since such flashlamp-pumped lasers are commercially available for more than 20 years. The main applications in the infrared are related to dermatology : vascular lesions, pigmentation lesions, hair removal and tattoo removal. In the UV, applications concern sterilization, photolithography, material processing...
At least, with their large spectral band around 800 nm, Cr:LiSAF and alexandrite are compatible with Ti:sapphire femtosecond systems. They can be seen as a very attractive alternative to amplify femtosecond pulses replacing the complex Ti:sapphire amplifiers pumped by frequency doubled neodymium lasers.
The members of the project ALEDxandrite are the Groupe Lasers du Laboratoire Charles Fabry (LCF) and EFFILUX, a small company operating in the LED lighting market for industrial applications. LCF and EFFILUX used to work together since 2012 via a previous research programm (ANR EDELVEIS 2012-2016). They fruitfully combined their know-how to invent a new generation of LED pumping, demonstrating innovative LED pumped neodymium lasers. The ALEDxandrite project will strongly benefit from this preliminary research work, increasing the efficiency and reducing the risks.
Between 2012 and 2016, the cost per optical watt has been cut down by a factor four. In the order of 0,5 euros per watt, LEDs are ten's to hundred's times cheaper than laser diodes.
The ALEDxandrite project has then a strong potential to open the way of a new class of lasers : compact, tunable and cheaper than ever.
Monsieur Francois BALEMBOIS (Laboratoire Charles Fabry - Institut d'Optique - CNRS)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
LCF Laboratoire Charles Fabry - Institut d'Optique - CNRS
Help of the ANR 278,852 euros
Beginning and duration of the scientific project: December 2017 - 36 Months