LH power modulation was recently used at JET to quantify experimentally the LH current drive efficiency and power deposition. A new approach was applied for the analysis of the amplitude and phase of electron temperature Te perturbations dTe(kwo) at different harmonics k of the modulation frequency wo. A solution of the Fokker-Planck equation combined with heat transport modelling was used to study the dependence of the ratio of the perturbation of different harmonics k and n, dTe(kwo) / dTe(nwo), and the phase shift of the harmonics df(kwo) on the plasma parameters and electron distribution function plateau width, which is directly connected to the current drive efficiency. The results of the modelling were compared with the experimental data to estimate the current drive efficiency. In addition, LH power deposition profiles were deduced from the radial dependence of df(wo). The maximum of the LH power deposition becomes more peripheral and with a reduced current drive efficiency at higher densities. In H-Mode plasmas, at pedestal densities above the LH accessibility limit, a large fraction of the power is absorbed beyond the separatrix. Finally, the experimental power deposition profiles are more peripheral than the calculated ones obtained from combined ray tracing and Fokker-Planck Plank modelling. The experimental results indicate that the LH power spectrum in the plasma is modified, with more power in the high N|| components.