Transition excitation at 09 μm by multiphoton pumping of Nd^3+-doped fibers

Abstract
Multiwavelength oscillations near 0.9 μm (i.e., 0.88–0.98 μm) have been obtained in a Nd3+-doped silica-based single-mode optical fiber. The laser pump wavelength is 1.064 μm, with an average pump power of approximately 1.8 GW/m2. The observed emission rate has reached a few percent. We discuss the possibility that this fluorescence or perhaps superfluorescence arises by multiphoton absorption.