Modification of the Near-Infrared Spontaneous Emission in Er3+-Activated Inverse Silica Opals

Ordered SiO2:Er3þ inverse opal films are fabricated by sol-gel technique incombination with a self-assembly method to examine their potential as a suitableplatform to tailor the spontaneous emission lifetime of Er3þ ions and its concentrationquenching (CQ). Good ordering on long-range scale is evidenced bymeans of scanning electron microscopy, whereas reflectance measurementsdisplay a green bright color, as it results from optical Bragg diffraction from the(111) crystal planes. Moreover, it is observed that the spontaneous decay rates(SDRs) of the inverse opals are suppressed, in contrast to the correspondingreference samples, due to the modulation of the effective refractive index (neff ), inagreement with the virtual cavity model. At the same time, the reduced CQ ofEr3þ is attributed to the periodic empty cavity of the inverse opals. These resultsdemonstrate that inverse opals can provide a tool for the enhancement of nearinfrared(NIR) luminescence.