Diode-Pump-Modulated Nd:YAG Laser

We have investigated the response of a luminescent diode-pumped cw Nd:YAG laser to a sinusoidal modulation of the pump intensity. For small modulation depths we found exact agreement with the relaxation oscillation resonance predicted by the linearized treatment of the coupled rate equations. For large modulation depths we obtained regular spikes at repitition rates between approximately 4 and 6 kHz with peak powers up to 100 times the cw power. Both the relaxation oscillation resonance (∼ 10–20 kHz depending on pump power) and the spiking could be self-excited by means of a feedback loop.