Stimulated Raman Scattering in Pb(MoO4)1−x(WO4)x with x = 0, 0.5, 0.8 and 1.0 with Combined Frequency Shifts on High- and Low-Frequency Raman Modes under Synchronous Picosecond Laser Pumping

Milan Frank,Ksenia A Gubina,Alexey N Shekhovstov,Petr G Zverev,Michal Jelínek,David Vyhlídal,Sergei N Smetanin,Václav Kubeček,Vladislav E Shukshin,Miron B Kosmyna

doi:10.3390/cryst12020148

Abstract

Comparative characteristics of spontaneous and stimulated Raman scattering in Pb(MoO4)1−x(WO4)x single crystals (x = 0, 0.5, 0.8, and 1.0) including both the high (ν1) and low (ν2) frequency internal anionic group vibrations have been investigated. It was found that among these crystals, Pb(MoO4)0.2(WO4)0.8 is the most suitable for multi-wavelength Raman laser in several Raman modes simultaneously. This is caused by the optimal relative Mo/W content corresponding to the most efficient coherent combination of the (MoO4)2− and (WO4)2− vibrations enhancing the output radiation characteristics of the synchronously pumped Pb(MoO4)0.2(WO4)0.8 Raman laser. Oscillation of up to twelve, closely spaced SRS components in a range of 1128–1360 nm and the strongest pulse shortening down to 1.16 ps in comparison with not only PbMoO4 and PbWO4 but also with all the earlier investigated nominally pure scheelite-like tungstate and molybdate crystals has been achieved.

Highlights

Interest in scheelite-type PbMoO4 and PbWO4 crystals first appeared in the 1960s after work was published considering them to be promising optical materials for acoustooptics [1]
It was found that among these crystals, Pb(MoO4)0.2(WO4)0.8 is the most suitable for multi-wavelength Raman laser in several Raman modes simultaneously. This is caused by the optimal relative Mo/W content corresponding to the most efficient coherent combination of the (MoO4)2− and (WO4)2− vibrations enhancing the output radiation characteristics of the synchronously pumped Pb(MoO4)0.2(WO4)0.8 Raman laser
PbMoO4—in acousto-optical modulators, deflectors and phase shifters [2]; PbWO4—in electromagnetic detectors in high-energy accelerators used for highenergy physics research at CERN [3]; PbMoO4 and PbWO4—in a scintillation detector for rare event and dark matter searches [4]

Summary

Introduction

Interest in scheelite-type PbMoO4 and PbWO4 crystals first appeared in the 1960s after work was published considering them to be promising optical materials for acoustooptics [1] Later, these crystals were recognized as very efficient for many applications due to their unique properties. It can help to artificially construct the widest and highest ν2 line as a coherent combination of the (MoO4)2− and (WO4)2− anionic group bending Raman modes to the natural Ag + Bg mode combination in the bending ν2 Raman line for radiation pulse shortening in (ν1 + ν2)-shifted SRS under synchronous picosecond pumping. The lasers generating at two or more wavelengths simultaneously are widely used in atmospheric detection, lidar system, and terahertz wave generation [25,26,27]

Raman Crystals Characterization

Experimental Setup

Findings

SRS in PbMoO4 and PbWO4