Visible-wavelength amplified spontaneous emission in a neodymium-doped optical fiber pumped at 1064 nm

Abstract
A neodymium-doped single-mode fiber emits light at 496 and 633 nm, as well as at several near-infrared wavelengths, when pumped by a mode-locked, Q-switched Nd:YAG laser operating at 1064 nm. A threshold peak pumping power of approximately 50 kW is required for the process; peak emitted powers of several watts were observed. The blue line is more than 15 nm wide at high pumping levels and possesses large temporal pulse dispersion across its spectrum. Amplified spontaneous emission via a three-photon pumping process is proposed to account for the phenomenon.