Ca 4 REO(BO 3 ) 3 crystals for green and blue microchip laser generation: from crystal growth to laser and nonlinear optical properties G. Aka a, * , E. Reino a , P. Loiseau a , D. Vivien a , B. Ferrand b,c , L. Fulbert b , D. Pelenc b , G. Lucas-Leclin c , Patrick Georges c a Laboratoire de Chimie Appliqu ee de l’Etat, Solide- CNRS-URA 1466 ENSCP, 11 rue P. et M. Curie, 75231 Paris Cedex 05, France b LETI/DOPT/STCO/laboratoire de Cristallogen ese Appliqu ee, CEA-Grenoble, 17, rue des Martyrs, 38054 Grenoble Cedex 09, France c Laboratoire Charles Fabry de l’Institut d’Optique, UMR 8501 du CNRS, Centre Universitaire, BP 147, 91403 Orsay Cedex, France Received 24 July 2003; accepted 9 February 2004 Available online 9 April 2004 Abstract We have taken advantage of congruent melting behavior of the nonlinear rare-earth oxoborate Ca 4 REO(BO 3 ) 3 family to perfect a process of collective fabrication of self-frequency doubling microchip laser based on Nd:GdCOB (Ca 4 Gd 1x Nd x O(BO 3 ) 3 ) crystals. The process goes from Czochralski boule to 1 · 3 mm 2 chips perfectly oriented (better than 0.1°) to the phase matching direction (h ¼ 90°, / ¼ 46°) in the XY principal plane, with dielectric mirrors directly deposited on both faces of the chips. 20 mW of self- frequency doubling output power at 530 nm was performed under 800 mW of diode laser as incident pump power at 812 nm. In addition, new compositions from the solid solution Ca 4 Gd 1x Y x O(BO 3 ) 3 (Gd 1x Y x COB) (x ¼ 0:13, 0.16, 0.44) have been grown by the Czochralski pulling method, in order to achieve noncritical phase matching (NCPM) second harmonic generation of 4 F 3=2 fi 4 I 9=2 Nd 3þ doped laser hosts. Three types of laser wavelengths have been chosen: Nd:YAP (YAlO 3 ) at 930 nm, Nd:YAG (Y 3 Al 5 O 12 ) at 946 nm, and Nd:ASL (Nd y Sr 1x La xy Mg x Al 12x O 19 ) at 900 nm. Angular acceptance measurements of these three types of com- positions present very large values, compared to pure GdCOB or YCOB oriented in critical phase matching configurations. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Ca 4 REO(BO 3 ) 3 crystal; Microchip laser; Green laser 1. Introduction Visible-emitting solid-state lasers are of practical interest in various fields of applications including med- icine, information processing and display, materials processing, etc. A very promising modality to obtain lasers in the blue spectral range would be the frequency doubling of the infrared 900–950 nm range emission from the 4 F 3=2 fi 4 I 9=2 Nd 3þ transition. Until now the best way to get green laser emission is to double the frequency of the 4 F 3=2 fi 4 I 11=2 Nd:YAG laser. However, using self-frequency doubling neodymium doped hosts a direct conversion could be obtained. The nonlinear rare-earth oxoborate Ca 4 REO(BO 3 ) 3 crystals is a borate family which offers the unique opportunity of being a multifunctional material [1–6,8– 13,15]. Czochralski pulling technique can be used to grow large dimension crystals of these oxoborate materials. Consistent data on nonlinear properties are now available for second harmonic generation [1,5,6, 17,18]. Gadolinium calcium oxoborate Ca 4 GdO(BO 3 ) 3 (GdCOB) was shown to be an efficient nonlinear optical crystal [1,2,11] grown from the melt in large size. GdCOB have been very well characterized regarding all the linear and nonlinear properties [3–5,7]. The effective NLO coefficient is in the range 0.5–1.8 pm/V depending if the fundamental wavelength is propagating in or out of principal planes. Reliable Sellmeier equations of GdCOB and YCOB were determined. The damage threshold is up to 1 GW/cm 2 at 1064 nm (6 ns pulses). The SHG * Corresponding author. Tel.: +33-1-4427-6707; fax: +33-1-4634- 7489. E-mail address: akagp@ext.jussieu.fr (G. Aka). 0925-3467/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2004.02.009 Optical Materials 26 (2004) 431–436 www.elsevier.com/locate/optmat