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

Abstract

Objective: Rate equations model has been formulated to simulate the simultaneous generation of two passive Q-switching pulses using one active medium. It is possible to separate them and employ each pulse in practical applications. Methods: The model was solved numerically by used Rungkutta-Fahelberg method. This model was tested in the study of the effect of saturable absorber ( Cr +4 : YAG ) ions concentration on the duration, energy, and power of the dual pulses which are generation by passive Q-switching of Nd +3 : YAG. Finding: The results of the numerical solution showed that the temporal behavior of photons density of passive Q-switching pulses and the population inversion density of active medium is good agreement with studies which dealt the theory of passive Q-switching, which enhances reliability using this model. Novelty: The mathematical model included six rate equations instead of three or four rate equations. It is based to simulate the 4 F 3/2 , 4 I 11/2 , 4 I 9/2 spectrum lines as a 4-level and 3-level energy schemes of Nd +3 : YAG active medium to get two passive Q-switching laser pulses at the same time (instantaneously) instead of one pulse. Can be separated into two pulses to employ each of them in applications.

Initial Transmission Influence on Saturable Absorber Absorption Activity of Passive Q-Switching Erbium -Doped Fiber Laser System

“…These crystals have a large absorption cross section and low saturable intensity at the laser wavelength [10,11 ]. Cr4:YAG crystal is widely adopted as saturable absorber for passively Q-switched laser generation [12,13], For a range of laser media, Cr +4 : YAG has also been successfully used as passive Q-switches, and its energy state can be illustrated by Figure (2) [14]. The absorption activity of SA plays an important role in determining the efficiency of laser optical systems which are used in the generation of high power pulses.…”

“…Energy state of Cr +4 : YAG[14] occurs when the SA is at the high absorption activity, or at small signal transmission of photons, then we can estimate…”