New Manifestation of Nonlinear Properties of Acentric Trigonal LaBGeO₅and Orthorhombic Gd₂(MoO₄)₃Laser Crystal-Hosts: Multiple Stokes and Anti-Stokes SRS and SHG Due to Cerenkov-Type Phase Matching

Abstract

We have discussed new optical potentialities in acentric Gd 2 (MoO 4 )3 and LaBGeO 5 laser crystal-hosts having simultaneously relatively high χ (2) and x(3) nonlinear susceptibilities. In particular, we show experimental results on efficient multiple Stokes and anti-Stokes stimulated Raman scatterjng and Raman induced four-wave mixing, as well as second harmonic generation with Cerenkov-type phase matching.

Tetragonal Ba2MgGe2O7- a novel multifunctional optical crystal with numerous manifestations of nonlinear-laser effects: almost sesqui-octave Stokes and anti-Stokes combs and cascadedχ(3)↔χ(2)lasing with involved second and third harmonic generation

“…[8][9][10]), we report in the present work on the observation of numerous manifestations of nonlinear-laser effects in the tetragonal barium magnesium germanate, Ba 2 MgGe 2 O 7 , with melilitetype structure, which is among the oldest host-materials for Nd 3+ lasants [11]. We also give linear optical properties of the title crystal and the results of an X-ray crystal structure analysis.…”

“…Mg Ge a b c Figure 1 (online color at www.lphys.org) (a) Fraction of the general melilite structure with coordination polyhedra, illustrating the three types of cation sites of the melilite structure type: eight-fold antiprismatically coordinated M [8] , tetrahedrally coordinated T(1) [4] and tetrahedrally coordinated T(2) [4] (see text Ba-O bonds are left out for clarity. Thermal displacement ellipsoids (50% probability level, scaling factor of displacement ellipsoids is 2.5) for all atoms are used tive for the realization of Raman laser converters with an efficiency of more than 50%, that can significantly enrich the wavelength assortment of known crystalline lasers.…”

“…Ba 2 MgGe 2 O 7 is a member of the large family of tetragonal, non-centrosymmetric melilite-type compounds with the general composition M [8] 2 T(1) [4] T(2) [4] 2 O 7 (see Fig. 1a for a graphical explanation of the used terminology), where the tetrahedrally coordinated position T (2) [12].…”

“…For instance, observed multi-wavelength equidistant coherent Stokes and anti-Stokes lasing components ("lasing combs"), that cover very wide spectral ranges in the UV, visible and near IR (in several cases up to two octaves, see, e.g., SrF 2 [2], CVD-diamond [3], BaF 2 [4], NH 4 H 2 PO 4 (ADP) and ND 4 D 2 PO 4 (DADP) [5], α-quartz [6]), open up new promising possibilities for the synthesis of different ultra-short (femtosecond) waveforms (pulses). χ (3) -and (χ (2) + χ (3) )-active crystals are also very attrac- Table 1 Overview of known melilite-type crystals with general formula M [8] 2 T(1) [4] T(2) [4] 2 O7, classified with respect to ordering of cations (and anions) on the respective sites (mixed crystals are not included). Cations A (1) 2+ and RE 3+ occupy the M site, A (2) 2+ are on T(1) site, X Top seeded solution growth [108] a)…”

Stimulated Raman scattering and cascaded nonlinear laser (χ(3) ↔ χ(2)) effects in tetragonal non-centrosymmetric Li2B4O7 single crystals

“…[6,7]). The widely used second har-monic generation (SHG) [8] (including Cherenkov type [9]), stimulated Raman scattering (SRS), and numerous Raman induced parametric processes in the majority of known non-centrosymmetric borates (see Table 1) make the availability of efficient conversion of visible and near-IR laser radiation into different specific wavelengths possible.…”