Measurement of the Cross-section for Stimulated Emission in Neodymium Glass

Abstract

A KNOWLEDGE of the cross-section of a laser material for stimulated emission is essential for calculations of the expected performance because it determines the relationship between the gain and the energy stored. Until now the stimulated emission cross-section at the peak of the line for the ⁴F_3/2−⁴I_11/2 transition in hosts doped with neodymium has been estimated from the fluorescent lifetime, τ, and the fluorescent linewidth, Δν, using the Fuchtbauer–Ladenburg formula for a transition with a depleted lower state where Δν is defined by σ_p Δν = ∫σ_vdν, n is the refractive index of the material and λ is the wavelength. The main difficulty in using this formula is that τ represents the fluorescent lifetime for the decay rate of the ⁴F_3/2−⁴I_11/2 state alone, whereas the observed decay rate of the fluorescence at 1.06µ includes the rates for non-radiative decay and for fluorescence at other wavelengths.