A computer approach to laser design

The problem of maximizing laser efficiency is usually approached through experimental study. The method proposed in this paper permits us to approximate the optimum design prior to the actual physical construction of the system. The efficiency of a four-level laser system is first defined as a product of six subefficiencies, each associated with one of the loss mechanisms operative in the system. Equations which relate the subefficiencies to physically measurable parameters are derived. The set of these equations constitutes the model for system efficiency. Based on the model, a program is written for the IBM 1620 digital computer. A sample problem involving the design of a neodymium doped glass laser oscillator is solved to illustrate the use of the model. The results are in general agreement with known theoretical and experimental properties of the pulsed four-level laser. In general, the efficiency increases with length, radius, doping density and pumping energy, and decreases as end reflectivities and pumping pulse time constant increase, within the restrictions imposed on the model by assumptions and approximations.