Study of the Spatiotemporal Behavior of LED-Pumped Ce:Nd:YAG Laser

Abstract

In this paper, the mode structure and time behavior of a LED-pumped Ce:Nd:YAG laser have been studied. Four blue LED bars with total 128 LEDs at 460 nm are utilized to pump a 3 mm diameter laser rod. Using a Cr 4+ :YAG passive optical switch with 96% initial transmission, and a low loss stable optical resonator and 0.7 J pumping energy, a single 17 micro-joules Q-switched laser pulse with 240 ns pulse-width and nearly TEM 00 mode profile was produced. By increasing the pumping energy E p up to 0.8 J, the mode structure remained intact. Further increasing of E p , the laser mode changed to TEM 10 . Numerical calculations show that the central high gain area of the laser rod and saturation mechanism of the passive Q-switch behaves like as a soft aperture to enforce the laser resonator to oscillate on a low order transverse mode. For laser free-running, the TEM 00 mode has not been achieved and the optical resonator produced high order transverse mode patterns.

Rate Equations Model to Simulate the Dual Generation of Nd+3: YAG Passive Q-Switched Laser Pulses

“…The model was tested by using it in numerical simulation of a laser system consist of Nd +3 : YAG used as AM and Cr +4 : YAG as a SA. The temporal behavior of each photons density of passive Q-switching pulse and population inversion density of AM ions resulting from the simulation showed good agreement with studies which dealt the theory of passive Q-switching (15)(16)(17) . This benchmark enhances reliability using the model.…”

Absorption Activity Investigation of Saturable Absorber for Dual Wavelengths in Laser Passive Q-Switching System

“…The characteristics of laser between the 4-level system and the quasi-three-level system produce a major difference. Because of small division of energy for each manifold, it is assumed that the relaxation times for the energy level within the manifold are also very small (10) .…”