LGYSB:Nd─High-Performance Lasing in the Near-Infrared Region

Abstract

La w Nd x Gd y Y z Sc 4−w−x−y−z (BO 3 ) 4 (LGYSB:Nd) crystals with different Y concentrations (z = 0.15, 0.05, and 0.025) have been grown by the Czochralski method for the first time. The LGYSB:Nd-type crystals exhibit an acentric structure similar to that of the natural mineral huntite CaMg 3 (CO 3 ) 4 , with space group R32. The composition of the LGYSB:Nd_3 (z = 0.025) crystal grown f r o m t h e s t a r t i n g m e l t c o m p o s i t i o n La 0.628 Gd 0.547 Y 0.025 Nd 0.05 Sc 2.75 (BO 3 ) 4 was measured by inductively coupled plasma mass spectrometry method, and it was found to be La 0.6794 Gd 0.4105 Y 0.0178 Nd 0.0381 Sc 2.8542 (BO 3 ) 4 . The transversal spatial distribution of the refractive index in the LGYSB:Nd_3 crystal was investigated. Third-order nonlinear optical susceptibility χ (3) of the LGYSB:Nd_3 crystal was determined from third-harmonic generation experiments with ultrashort (fs) laser pulses. The optical transmission spectrum was measured in the range of 200−2000 nm. The absorption cross-section at 808 nm in σ-polarization was determined to be 1.18 × 10 −19 cm 2 for the LGYSB:Nd_3 crystal. The 10K absorption spectra revealed that the Nd 3+ ions occupy only La 3+ cationic sites in the LGYSB host matrix. The emission cross-section at 1064 nm in σ-polarization was determined to be σ em (σ) = 1.74 × 10 −19 cm 2 for the LGYSB:Nd_3 crystal. The fluorescence lifetime was found to be τ = 115 μs for all of the LGYSB:Nd crystals. The LGYSB:Nd_3 laser was operated at an emission wavelength of 1062 nm with very high slope efficiencies of η sa = 0.74 and η sa = 0.64 in quasi-cw and cw regimes, respectively.

Crystal Structure and Optical Characteristics of K2Nd2O(BO3)2

“…[6] After that, some other crystals have been investigated for microchip lasers, including Nd 3 + ions doped YVO 4 , [7] GdVO 4 , [8] KGd(WO 4 ) 2 , [9] etc. Recently, some borates have also been proved to be good laser matrices on account to their high laser-induced damage thresholds and excellent thermophysical performances, such as Nd : La 2 CaB 10 O 19 (Nd : LCB), [10] Nd : La 2 CaB 8 O 16 (Nd : LCB 8 ), [11] La w Nd x Gd y Y z Sc 4-w-x-y-z -(BO 3 ) 4 (Nd : LGYSB), [12] Nd : β-LaBSiO 5 , [13] Nd : Ca 3 La 2 (BO 3 ) 4 , [14] Nd : MgGdB 5 O 10 , [15] Nd : GdAl 3 (BO 3 ) 4 , [16] etc.…”