Coherent　optical　phonons　in　terbium　vanadate　(TbVO4)　are　investigated　by　using　femtosecond　time-resolved　pump-probe　spectroscopy　at　temperatures　from　20　to　300　K.　Combined　with　the　Raman　spectrum,　the　coherent　phonon　mode　is　attributed　to　an　optical　phonon　mode　of　B1g　symmetry.　The　main　generation　mechanism　of　the　coherent　optical　phonons　is　revealed　to　be　the　impulsive　stimulated　Raman　scattering.　The　temperature　dependence　of　the　dephasing　time　reveals　that　the　main　mechanism　of　the　coherent　phonon　population　decay　is　anharmonic　phonon-phonon　coupling,　which　causes　a　redshift　of　the　coherent　phonon　frequency　with　increasing　temperature.　©　2011　Springer-Verlag.