Comparative spontaneous Raman spectroscopy of crystals for Raman lasers

Abstract

A comparison of the spectroscopic parameters of Raman-active vibronic modes in various crystalline materials with a view to the use of these crystals for stimulated Raman scattering (SRS) is presented. It includes data on the Raman frequency shift, linewidth, integral, and peak Raman scattering cross sections. For steady-state SRS the highest Raman gain coefficient has been proved to be in barium nitrate and sodium nitrate crystals; for transient SRS it is expected to be in lithium niobate and tungstate crystals. Barium tungstate and strontium tungstate are proposed as new highly efficient Raman materials for both SRS cases.

Structural, spectroscopic, and tunable laser properties ofYb3+-dopedNaGd(WCascales1, Serrano2, Esteban‐Betegón3 et al. 2006Phys. Rev. B1414810View full textAdd to dashboardCite

“…The calculated dephasing time is 0.53 ps and this value is 3-4 times shorter than in the monoclinic double tungstates KT͑WO 4 ͒ 2 ͑T = Gd, Y, Yb͒. 27 The difference is even larger if we compare with ordered tetragonal tungstates with scheelite structure ͑PbWO 4 , CaWO 4 , SrWO 4 , BaWO 4 ͒. 26,27 Hence NaGdW is more suitable for operation with shorter pulses ͑e.g., 10 ps͒ maintaining the stationary regime of stimulated Raman scattering.…”

“…26 This line of NaGdW is known for its potential for stimulated Raman scattering. 27 We measured polarized Raman spectra at room temperature with single crystals of lowdoped Yb:NaGdW ͑Fig. 4͒ for better comparison with other related tungstates with ordered or disordered structure as well as for identification of the phonon bands in the low temperature absorption/emission spectra of Yb 3+ .…”

“…27 The difference is even larger if we compare with ordered tetragonal tungstates with scheelite structure ͑PbWO 4 , CaWO 4 , SrWO 4 , BaWO 4 ͒. 26,27 Hence NaGdW is more suitable for operation with shorter pulses ͑e.g., 10 ps͒ maintaining the stationary regime of stimulated Raman scattering. Note that the observed FWHM in NaLa͑WO 4 ͒ 2 and NaY͑WO 4 ͒ 2 is similar.…”

“…Note that the observed FWHM in NaLa͑WO 4 ͒ 2 and NaY͑WO 4 ͒ 2 is similar. 26,27 The factor group analysis and the classification of the phonon frequencies for the I4 symmetry can be found, e.g., in Ref. 19 where this SG was assigned to NaBi͑WO 4 ͒ 2 .…”

Laser crystals and ceramics: recent advances

“…The product (1/∆ν R )( dσ/ dΩ) may be considered as the spectroscopic parameter providing a measure of the peak intensity of the corresponding spontaneous Raman transition. This figure of merit can be used in a comparative selection for suitable SRS-active crystalline media [532]. In consequence, highgain materials should have a small ∆ν R value of intense Raman shifted lines.…”