Kochkurov Leonid A. RussiaSaratovSaratov State Technical University named after Yuri Gagarin, 77, Politechnicheskaya str., Saratov, 410054, Russialkochkurov@gmail.com Author's articles Difference-Frequency Generator and Optical Parametric Oscillator Pumped by a Semiconductor Disk Laser: Comparative Study with a Time Delay Model