THERMALLY INDUCED BIREFRINGENCE AND MODE SELECTION IN THE CAVITY OF A PASSIVELY g-SWITCHED DIODE-PUMPED Nd:YAG LASER

• Published in: Journal of applied spectroscopy Vol. 89; no. 5; pp. 835 - 838
• Main Authors: Bogdanovich, M.V, Grigor'ev, A.V, Dudikov, V.N, Ryabtsev, A.G, Ryabtsev, G.I, Tatura, P.O, Shpak, P.V, Shchemelev, M.A
• Format: Journal Article
• Language: English
• Published: Springer 01.11.2022
• Subjects: Analysis; Circuit components; Lasers
• ISSN: 0021-9037; 1573-8647
• DOI: 10.1007/s10812-022-01433-2

Operating regimes of an optical system consisting of a compact pulsed master diode-pumped Q-switched Nd:YAG laser and triple-crystal (KTP) ring cell of an optical parametric oscillator have been investigated. It was experimentally shown that the frequency-selective properties of a passive Q-switched unit in natural mode selection are enhanced by creating a Lyot polarization interference filter with the phase plate in the form of a laser active element with thermally induced birefringence and a polarizer. Such Lyot filter appears in the Nd:YAG laser cavity during operation at relatively high energy and repetition rate of radiation pulses (60-100 mJ, 20 Hz). The combined action of the natural mode selection process and the Lyot filter ensures stable operation of a passive Q-switched Ng:YAG laser in single-frequency lasing mode (the lasing bandwidth is <57 MHz). The master single-frequency pulsed Nd:YAG laser ([lambda] = 1.06 [micro]m) allows the energy of pulses applied to the input of the optical parametric oscillator to be reduced by greater than 1.5 times while maintaining the specified energy level of the output pulses (30 mJ, [lambda] = 1.57 [micro]m). An additional increase in the efficiency of the optical parametric oscillator conversion is achieved by introducing a two-lens 1.3 * telescope into the master laser cavity.