High efficiency angular non-critical phase matching for Ti:sapphire laser realized on LaCa₄O(BO₃)₃single crystals

Nonlinear optical characterizations of monoclinic LaxGd1−xCa4O(BO3)3 (x = 1, 0.09, 0.13) single crystals

“…The fundamental and SHG waves were separated by a filter, and then detected and measured by a spectrometer and power meter, respectively. For LaCOB and GdCOB crystals, the d eff of type-I A-NCPM SHG along the x axis and type-II A-NCPM SHG along the z axis were calculated to be zero, and the type-II A-NCPM SHG wavelength (>3 µm) along the x axis could not been measured for it go out of the OPO turning range used [11,16]. The accurate A-NCPM SHG wavelengths (Y type-I, Z type-I and Y type-II) were measured and listed in table 2.…”

“…Compared with the traditional KH 2 PO 4 (KDP), KTiOPO 4 (KTP), BaB 2 O 4 (BBO) and LiB 3 O 5 (LBO) crystals, they were found to possess qualities of good thermal properties, high optical transparency, low walk-off angle, relatively large nonlinearity and angular acceptance [1,2]. In recent years, extensive studies have been carried out for laser and NLO applications, such as second-order nonlinear frequency conversion [6][7][8][9][10][11], ultrafast laser [12] and self-frequency-doubling laser [13] devices.…”

“…Among the ReCOB crystals, YCOB, TmCOB, Gd x Y 1 − x COB, Gd x Lu 1 − x COB, Gd x Sc 1 − x COB, GdCOB and LaCOB have attracted lots of attention for NLO applications, where the optical properties were found to vary with different rare-earth (Re) ions [2,11,[14][15][16][17][18]. For example, TmCOB crystals were found to possess the largest effective NLO coefficients (d eff ) in a ZX principal plane and the shortest A-NCPM wavelengths along the y axis among the pure ReCOB (Re: Tm, Y, Gd and La) crystals [7].…”

“…Furthermore, the birefringence of Gd x Y 1 − x Ca 4 O(BO 3 ) 3 (Gd x Y 1 − x COB) crystals was found to be adjustable by changing the compositional parameter x, and the type-I A-NCPM third harmonic generation (THG) of Nd : YAG laser (1064 nm) could be realized along the Y optical principal axis [15][16][17]. In addition, the type-I A-NCPM second-harmonic generation (SHG) wavelengths along the y axis for Gd 0.871 Lu 0.129 COB, Gd 0.93 Lu 0.07 COB, Gd 0.96 Sc 0.04 COB and LaCOB crystals were measured to be 799 nm, 812 nm, 814 nm and 808 nm, respectively, and these crystals can be used to direct frequency doubling Ti : sapphire laser for generating the blueviolet ultrafast laser pulse [8,11,14]. For all the existing ternary borates Re x Gd 1−x COB (Re: Sc, Lu and Y) NLO crystals, the ionic radius of La 3+ (1.032 Å) ions was found to be much larger than those of the Sc 3+ (0.750 Å), Lu 3+ (0.861 Å), Y 3+ (0.890 Å) and Gd 3+ (0.938 Å) ions [19], which might lead to a large difference in A-NCPM wavelengths between La x Gd 1−x COB (0 < x < 1) and the other Re x Gd 1−x COB (0 < x < 1, Re: Sc, Lu and Y) crystals.…”

“…However, there were no reports on the A-NCPM properties of La x Gd 1−x COB (0 < x <1) crystals. Furthermore, the previous reports on the NLO properties of LaCOB crystals were limited to the optical principal planes [2,11,20], which were far fewer than the investigations of YCOB and GdCOB crystals with the identical structure [1, 6-10, 14-18, 21-29]. In this paper, the optimal PM direction at 1064 nm out of the principal planes for LaCOB crystals was determined, based on which, high efficient SHG was realized by using a 1064 nm Nd : YAG pico-second laser.…”