Persistent spectral hole-burning in CuBr nanocrystals

Persistent hole-burning phenomena in ion-doped glass and organic-molecule-doped organic glass have been well known. In recent years semiconductor nanocrystals have been studied extensively because of their novel optical properties such as large optical nonlinearities, and their possibility for applications, such as lasers, ultrafast optical devices, and so on. However, so far "persistent spectral hole-burning (PSHB)" phenomenon in semiconductor nanocrystals has never been reported until the PSHB phenomenon was observed in CdSe and CuCl nanocrystals in our laboratory. Therefore, we may be able to find the other semiconductor nanocrystals which show persistent hole-burning phenomenon. In this publication, we report the persistent hole-burning phenomenon in CuBr semiconductor nanocrystals embedded in glass. Our experiment shows the spectral hole in CuBr nanocrystals remains for more than 8 hours without any detectable relaxation.