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Morozov Y. A., Balakin M. I., Kochkurov L. A., Morozov M. I. Difference-Frequency Generator and Optical Parametric Oscillator Pumped by a Semiconductor Disk Laser: Comparative Study with a Time Delay Model. *Izvestiya of Saratov University. Physics *, 2019, vol. 19, iss. 1, pp. 34-42. DOI: 10.18500/1817-3020-2019-19-1-34-42

# Difference-Frequency Generator and Optical Parametric Oscillator Pumped by a Semiconductor Disk Laser: Comparative Study with a Time Delay Model

Background and Objectives: High-resolution spectroscopy is known to need sources of coherent radiation in the mid- and farinfrared spectral bands. Sources based on optical nonlinear interaction (a difference-frequency generator and an optical parametric oscillator) are known to be almost ideally suitable for an application. Intracavity realizations of the devices with a nonlinear crystal located in the cavity, can likely be made simple, compact and easy to use. Both a difference-frequency generator and an optical parametric oscillator may be thought of as a time delay dynamical system. The study of dynamical system stability and its transient dynamics that follows the primary pump turning on, is thus of importance. Such an analysis is among the main objectives of the manuscript. Materials and Methods: The mathematical model based on the differential rate equations with time delay has been proposed and numerically simulated. The linear stability of the steady state operation has been studied using the DDEBIFTOOL package. The transient dynamics of the dynamical system is analyzed with the Fortran codes. Results: The steady state operation point of the ICSRO is stable in a limited area the parameters, while that of the ICDFG keeps the stability for all values of the device parameters. The steady state operation takes on the order of 1000 carrier lifetimes to be settled. Conclusion: The findings obtained are of importance and have to be taken into account as the ICSRO and ICDFG to be applied in the high-resolution spectroscopy.

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