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Photoreactive random media containing silver nanoparticles (Ag NPs) have been fabricated, and hole burning effects based on the interference of multiply scattered light have been investigated. Through the analysis of hole profiles, transport mean free path ℓ is estimated for the light with the wavelength of 585 nm. We find that ℓ in the samples embedded with Ag NPs is much shorter compared with that in a medium containing the same amount of titania (TiO2) NPs, indicating that Ag NPs scatter 585 nm lightwaves much stronger than TiO2 NPs because of their larger scattering cross sections due to the localized surface plasmon resonance.

Optical hole burning is a high resolution spectroscopy technique that is used to characterize optical materials. It has applications in optical data storage. Rare-earth ion doped crystals, glasses; color centers and dye doped polymers are candidate materials for this purpose. Rare-earth ion doped glasses produce transient as well as persistent spectral holes. The nature of the hole burning depends on the glass preparation methods. Hole burning efficiency depends on the glass composition as well. We investigated persistent spectral hole burning studies in europium doped glasses such as sodium borates, silicates, borosilicates, germinates and tellurites. The hole stability as well as hole burning efficiency was investigated by varying the glass composition. Sodium silicate glasses did not retain more than one hole at a time. On the other hand hole burning was achieved with a mW power. Sodium borate glasses retained multiple holes but they required higher power (box than silicates) to burn a hole. However multiple hole burning was achieved in sodium borosilicate glass at moderate powers. In borates, silicates and borosilicates hole burning occurred by a charge exchange between the excited Eu3+ ion and a neighboring Eu2+ ion or a defect. Hole burning efficiency also increased with the abundance of Eu2+ to some extent. However both photophysical as well as photochemical mechanisms were found to be responsible for hole burning in sodium germante glass. The effect of Y3+ was investigated on hole burning. Y3+ increased the abundance of Eu2+ and also the hole burning efficiency. We also observed high temperature hole burning in europium doped sodium telluride glass.