Research Projects

The objective of the ANR project PULSE (for Plastic Ultrashort LaSErs), started in 2021, is to demonstrate the possibility of obtaining laser operation in unprecedented temporal regimes, namely  an ultrashort pulse regime with high repetition rates . We will thus seek to produce the first mode-locked organic semiconductor laser.

Global strategy consists in implementing recently developed organic materials in innovative laser architectures. Achieving this goal requests adressing two important challenges. The first one is linked to the piling up of triplet excitons, which prevents organic lasers from operating in the CW regime, which in turn does not allow for a stable mode-locking regime to set up. Second challenge is to find an adequate saturable absorber. To solve these two issues, novel materials have been identified.

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Collaborations

This project is a collaborative work between the Organic Photonics group at Laser Physics Lab (S. Chénais, S. Forget) in Université Sorbonne Paris Nord (Villetaneuse), and the Laser Group at Laboratoire Charles Fabry (LCF), Institut d’Optique Graduate School (P. Georges, F. Druon) in Saclay. Other collaborations in relation with this project are also active with several groups of chemists in France and the Adachi group in Kyushu University, Japan.  

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Funding : ANR 2020-2024

An LED-pumped luminescent concentrator (LC) is a parallelepiped-shaped luminescent material with LEDs on its large sides. After absorbing light from the LEDs, the material re-emits light into the LC which is guided to its edges. Concentration is achieved through total internal reflections. This leads to a luminance 10 to 20 times higher than that of the LEDs. This is an emerging field of research with a very high disruptive potential.

The aim of the NewLight project is to develop concentrators over a large part of the optical spectrum (visible SWIR-short-wavelength infrared- and MWIR-medium-wavelength infrared) with a systematic, multidisciplinary approach, combining materials and systems.

This project aims at pushing organic lasers beyond today’s limits in terms of temporal regimes in order to make them compatible with a much wider range of applications. Our main objective will be to seek True continuous-wave operation in a Vertical Cavity Resonator, establishing guidelines for the choice of new materials and device structures. Attaining such a regime will unlock the possibility for ultrafast pulse generation, and will open the way towards electrical pumping.

In this project, our ambition is to combine for the first time theoretical calculations of triplet absorption bands, chemical synthesis of both small and macromolecules, as well as photophysical characterizations in order to realize a screening of novel molecular structures and identify new candidates for electrically-pumped organic lasers covering the whole visible spectrum.

The goal of the EDELVEIS projectwas to develop new tunable lasers in the visible (organic materials) and in the near infrared (bulk crystals including Ti:saphirre crystals). These laser systems will combine simplicity and compacity at an ultra low cost compared to today laser sources, thanks to the LEDs as pump sources.

Today pumping systems are generally frequency doubled lasers emitting in the green with 3 conversion stages. Their complexity and cost strongly limit the development of tunable lasers in the visible. LED pumping may completely change the paradigm with a dramatic cost reduction (2 to 3 orders of magnitude). At the beginning of the project only few publications were reported on LED pumping.

Differents results have been obtained during the project :

- first demonstration of a LED pumped Nd:YVO4 laser,

- first demonstration of an indirect LED pumped laser with a light concentrator,

- first demonstration of a LED pumped alexandrite laser.

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At LPL, our main contribution was the developpment of luminescent light concnetrators (characterisation and modelling essentially)

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Do you prefer a strong, powerful red laser or a smooth, delicate blue laser with a soft degradation finish ? Pick up the good capsule and travel to your favorite part of the optical spectrum !

In this project, we moved a thin sensing layer inside a working OLED to probe the triplet diffusion length. A theoretical model was also applied and the interplay of microcavity effects and direct recombinations is demonstrated experimentally.

We propose a new kind of architecure for organic laser resonators, namely a Vertical External Cavity Surface emitting Organic Laser. Alongside with enhanced performances (diffraction limited beam, record efficiency tahnks to longitudinal pumping), this geometry allows a great versatility. Being very modulable (mirrors, cavity length, intracavity elements), it is a very nice toy to unravel the mysteries of organic lasers !

With this project we develop several OLEDs in collaboration with CEA at Saclay, from a state to the art blue fluorescent diode to a red one using new efficient red dyes. A funny part of the project was to design an OLED cavity, playing on the intracavity optical field profile, the singlet diffusion depth and two complementary colors to produce a nice White OLED.