Regenerated cellulose as a porous silica composite template for random laser emission

Scattering medium diffuses light, which normally is not interesting for photonic applications. However, multiple scattering allows trapping light inside of a material, increasing the photon lifetime that can be amplified by a gain medium. Therefore, such scatters distribution combined with light amplification is one of the main principles of random laser phenomena. Here, we described an innovative way to produce highly porous material; porous cellulose to deposit an aluminoxane-epoxy-siloxane hybrid, which can be used as a template for random laser application. The sol-gel methodology was employed to obtain the porous cellulose and Boehmite-GPTS hybrids. The composite (cellulose plus hybrid) was heated at 600 degrees C to decompose the cellulose fiber, generating a 3D porous alumina-silica network, to which a Rhodamine B ethanol solution was added to act as the laser gain medium. Samples were fully characterized, and random laser studies were performed by using the second harmonic (532 nm) of a Nd:YAG laser with pulse width of 100 ps as the excitation source. Incoherent feedback laser emission was detected for samples pumped with fluences higher than 62 mJ/mm(2). Laser characteristics, such as fluence threshold and emission band width were determined. (AU)