Transversally diode-pumped Q-switched Nd:YAG laser with improved power and spatial characteristics T.V. Bezyazychnaya, M.V. Bogdanovich, A.V. Grigor'ev, V.V. Kabanov, O.E. Kostik, Y.V. Lebiadok, K.V. Lepchenkov, V.V. Mashko, A.G. Ryabtsev, G.I. Ryabtsev n , M.A. Shchemelev, L.L. Teplyashin Q1 B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Nezalezhnasti Ave. 68, 220072 Minsk, Belarus article info Article history: Received 8 February 2013 Received in revised form 5 June 2013 Accepted 11 June 2013 Keywords: Solid-state laser Diode pumping Lasing parameters abstract The power and output beam spatial properties of the transversally diode-pumped Q-switched Nd:YAG laser with the active element surrounded by the low-absorption light-scattering layer have been investigated. The layer consisted of the bonding agent in which the solid particles, like aluminum oxide or magnesium oxide, effectively scattering the light was uniformly distributed. The particle diameter was mainly in the range of 2–5 μm. It has been shown that application of such layer to the diode-pumped Q-switched Nd:YAG laser head allows suppressing the amplified spontaneous emission and/or internally circulating parasitic lasing modes. At the optimized concentration of the light-scattering solid particles the output lasing pulses with the energy of 188–210 mJ (the wavelength of 1064 nm, the pulse repetition rate of 30 Hz) and improved spatial characteristics were obtained using the pump unit based on three laser diode matrixes. & 2013 Published by Elsevier B.V. 1. Introduction Wide spread occurrence of the transversally diode-pumped neodymium solid-state lasers in commercial optical systems stimulates investigations pointed at an improvement of basic properties of the light sources. The increase of the output Q-switched lasing energy E out and the smoothing of the output beam profile are of considerable importance for such devices. It is desirable to improve the energy and spatial Nd:YAG laser performance concurrently with an enhancement of total light source efficiency. As it was shown for the lasers excited by flash lamps [1–4] the lasing gain and E out values are drastically saturated at high excita- tion levels if the large-size Nd:YAG active element (AE) with a high concentration of neodymium ions is used. This effect was chiefly explained through the use of parasitic transitions related with the amplified spontaneous emission (ASE) and/or internally circulating parasitic lasing (PL) modes. Special treatment of the AE side surfaces or bonding the edge claddings absorbing the ASE and/or PL modes was proposed for suppressing the development of the parasitic radiation fluxes [1,5,6] and, consequently, for increasing E out . Nevertheless, for the reasons of growing demands for the output parameters of modern optical systems further efforts must be made in the field of upgrading the neodymium lasers. This general problem becomes more complicated as one goes to the powerful transversally diode-pumped solid-state lasers specifi- cally due to a markedly nonuniform distribution of the absorbed pump radiation within AE [7]. Several optical schemes with special diffuse [8] or specular [9,10] reflectors on outer surfaces of the AE cooling glass tube have been proposed. Although, the task consisting in an effective suppressing of the ASE and/or PL modes at the stage of a rising of the AE inversion population throughout a duration of the pump pulse of the Nd:YAG laser in the Q- switched mode is still actual. This work deals with the investigation of power and spatial properties of the transversally diode-pumped Q-switched Nd:YAG laser which active element is surrounded by the special side- mounting ring layer. The purpose of this layer is the scattering of the pump radiation beams without appreciable absorbtion and the suppression of the development of the ASE and/or PL mode in the AE volume before a completion the output lasing pulse formation. The output beam energy and spatial characteristics of the developed Nd:YAG laser depending on the optical properties of the light- scattering layer are analyzed. 2. Experiment The scheme of the experimental setup is given in Fig. 1. It allows measuring the energy and spatial characteristics of the spontaneous and lasing radiation of the transversally pumped 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/optcom Optics Communications 0030-4018/$ - see front matter & 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.optcom.2013.06.024 n Corresponding author. Q2 Tel.: +375 17 2840398; fax: +375 17 2840879. E-mail addresses: ryabtsev@dragon.bas-net.by, ryabtsev@ifanbel.bas-net.by (G.I. Ryabtsev). Please cite this article as: T.V. Bezyazychnaya, et al., Optics Communications (2013), http://dx.doi.org/10.1016/j.optcom.2013.06.024i Optics Communications ∎ (∎∎∎∎) ∎∎∎–∎∎∎