A team of experts has developed a new system of imaging nanoparticles, which consists of a high-precision, short-wave infrared imaging technique. This method allows the photoluminescence lifetimes of rare-earth doped nanoparticles to be captured in the micro- to millisecond range.
Photoluminescence Lifetime Imaging Microscopy
As strategic metals, rare-earth elements possess unique light-emitting properties, which make them potential research tools in cutting-edge science. Additionally, the photoluminescence lifetime of nanoparticles doped with these ions shows the advantage of being minimally affected by external conditions.
Because of this, measuring this property through imaging offers data from which accurate and highly reliable information can be derived. However, while this field shows remarkable progress, the existing optical systems for this type of measurement are less than ideal.
Conventional optical systems can only provide limited possibilities because of limited imaging speed, inefficient photon detection, and low sensitivity. Currently, the most common method in measuring the photoluminescence lifetime of rare-earth doped nanoparticles involves counting time-correlated single photons.
This technique requires repeated excitations at the exact location since the detector can only process a limited number of photons for each excitation. The long photoluminescence lifetimes of nanoparticles doped in rare-earth metals in the infrared spectrum restrict the repetition rate of the excitation process. As a result, building the photoluminescence intensity decay curve needs much longer pixel dwelling time.
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Pushing the Limits
To address this challenge, a group of experts combined streak optics with a high-sensitivity camera to develop SWIR-PLIMASC (SWIR for short-wave infrared and PLIMASC for photoluminescence lifetime imaging microscopy using an all-optical streak camera). They are led by professors Jinyang Liang and Fiorenzo Vetrone from the énergie Matériaux Télécommunications Research Center at the Institut national de la recherche scientifique (INRS).
The device greatly improves the mapping of the optical properties of short-wave infrared photoluminescence lifetimes. This feature allows the tool to be the first high-sensitivity, high-speed SWIR imaging system in optics. With the help of this device, photoluminescence lifetimes can be directly captured in one shot with a 1D imaging speed that can be tuned from 10.3 kHz to 138.9 kHz.
Finally, allocating the temporal information of photoluminescence to various spatial positions ensures that 1D photoluminescence intensity decay can be recorded in a single snapshot without repeated excitation. This will allow the experts to conduct the process with high sensitivity while saving time.
This discovery, discussed in the paper "Short-wave Infrared Photoluminescence Lifetime Mapping of Rare-Earth Doped Nanoparticles Using All-Optical Streak Imaging," paves the way for groundbreaking applications, especially in the fields of biomedicine and information security.
In the biomedical field, the breakthroughs made possible by SWIR-PLIMASC have the potential to fight cancer and detect tumors earlier and in a more accurate way. Moreover, the innovative system can store information at enhanced security levels, particularly in preventing falsified documents and data. These results will enable scientists to synthesize rare-earth nanoparticles with more interesting optical characteristics in fundamental science.
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