Simulation of the energy transfer upconversion effect on properties of passively Q-switched laser pulse
摘要
The effect of energy transfer upconversion (ETU) on the properties of a passively Q‑switched (PQS) laser pulse is simulated using the optical system consisting of Nd+3:YAG and Cr+4:YAG as an active medium and saturable absorber, respectively. The rate equation model is proposed and calculated numerically by the Runge-Kutta-Fehelberg method. The results of the proposed model show good agreement for the time behavior of the population inversion density and the photon number density of the PQS laser pulse with the previous theoretical results of the same system. The benchmark enhances the reliability using the model. The simulation shows that upconversion operations lead to a decrease in the pulse energy and increase in the pulse duration. Calculation results show that the ETU effect results in a 3.735% increase in the pulse duration due to a decrease in the pulse energy by 1.226%, and its power reduction by 5.084%. In the case without the ETU effect, the pulse generates at an earlier time than in the case with the ETU effect.