Concentration quenching in fine-grained ceramic Nd:YAG.

Area of Science:

• Materials Science
• Solid-State Physics
• Laser Spectroscopy

Background:

• Ceramic Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) is a crucial laser material.
• Previous studies reported inconsistent fluorescence lifetimes, particularly at varying Neodymium (Nd) concentrations.
• Discrepancies were often attributed to excitation pulse duration effects.

Purpose of the Study:

• To resolve inconsistencies in the fluorescence decay kinetics of ceramic Nd:YAG.
• To elucidate the concentration-dependent mechanisms governing Nd:YAG fluorescence.
• To differentiate between short-pulse and long-pulse excitation effects on fluorescence decay.

Main Methods:

• Investigated concentration-dependent fluorescence decay kinetics of ceramic Nd:YAG.
• Employed short-pulse excitation to accurately capture decay dynamics.
• Analyzed fluorescence decay curves to identify exponential and nonexponential behavior.

Main Results:

• Observed nonexponential fluorescence decay for Nd concentrations exceeding approximately 1% atomic under short-pulse excitation.
• Identified energy migration to cross-relaxing Nd ions as dominant at longer times.
• Determined single-step energy transfer to randomly distributed quenching sites dominates at earlier times.

Conclusions:

• Short-pulse excitation reveals complex, nonexponential decay kinetics in Nd:YAG, contradicting earlier long-pulse studies.
• Direct cross-relaxation between individual Nd ions occurs below 4% atomic concentration.
• At higher concentrations, resonant energy transfer to Nd pairs becomes the primary quenching mechanism.