Strong Near-infrared Avalanche Photoluminescence from Ag Nanowire Arrays

Ag nanowire (NW) arrays with NW diameter d _NW?=?12–120 nm were electrodeposited in anodic aluminum oxide templates. Strong avalanche photoluminescence (PL) from Ag NW arrays with small d _NW were observed near 914 nm by using picosecond laser at the excitation wavelength 808 nm, which is originated from the plasmon-enhanced radiative intraband transitions. The peak PL intensity of the avalanche PL from the sample with small diameter d _NW?=?12 nm is about 10² times stronger than that of the linear PL from the sample with large diameter d _NW?=?120 nm. The opposite excitation polarization dependence and emission polarization distribution of the PL from Ag NW array with d _NW?=?12 nm and d _NW?=?120 nm were also observed.