Multi-wavelength continuous-wave Nd:YVO₄ self-Raman laser under in-band pumping*

Abstract

Multi-wavelength continuous-wave self-Raman laser with an a-cut composite YVO4/Nd:YVO4/YVO4 crystal pumped by an 879-nm wavelength-locked laser diode is demonstrated for the first time. Multi-wavelength Raman lasers at 1168.4, 1176, 1178.7, and 1201.6 nm are achieved by the first Stokes shift of the multi-wavelength fundamental lasers at 1064, 1066.7, 1073.6, 1084, and 1085.6 nm with two Raman shifts of 890 and 816 cm−1. A maximum Raman output power of 2.56 W is achieved through the use of a 20-mm-long composite crystal, with a corresponding optical conversion efficiency of 9.8%. The polarization directions of different fundamental and Raman lasers are investigated and found to be orthogonal π and σ polarizations. These orthogonally polarized multi-wavelength lasers with small wavelength separation pave the way to the development of a potential laser source for application in spectral analysis, laser radar and THz generation.

Multifunctional Optical Crystals for All-Solid-State Raman Lasers

“…Its strongest vibrational Raman mode is located at 890 cm −1 with Raman line width of 3.0 cm −1 and Raman gain coefficient of~5 cm/GW [14]. In addition, two weak Raman shifts are 816 and 259 cm −1 with respective Raman gain coefficients of 2.6 and 2.3 cm/GW for c-cut Nd:YVO 4 crystal with Z(XX) scattering configuration [60]; and 840 and 379 cm −1 with respective Raman gain coefficients of 2.6 and 0.9 cm/GW for a-cut Nd:YVO 4 crystal with X(ZZ) scattering configuration [81]. The Nd-doped YVO 4 crystal belongs to the zircon type D 4h tetragonal space group, and its stimulated radiation cross section parallel to the c axis (a-cut, σ = 25 × 10 −19 cm 2 at 1064 nm) is four times higher than the cross section orthogonal to the c axis (c-cut, σ = 6.5 × 10 −19 cm 2 at 1066 nm) [24].…”