Novel photonic devices, based on time-dependent dielectrics, to shift the optical frequency, may be conceived from two complementary principles, Doppler shift and time refraction, and possibly realized as as single cavities or as Coupled Resonator Optical Waveguides (CROWs). Simulations with the finite-difference time-domain method bore out these possibilities and also provided design rules. Preliminary experiments, limited to a pulsed excitation (without any frequency shift) of whispering gallery modes in a LiNbO3 whispering gallery disk resonator in a full fiber-optics setup, the first experiments of an optical whispering-gallery resonator functioning in the steady-pulsed regime, led to a consistent Q-factor measurement between CW and pulsed ringdown characterization. The repetition rate was tuned to an integer submultiple 1/N of the free spectral range of the resonator. The output rate of the resonator was equal to the input rate multiplied by N, thereby showing functionality as a frequency multiplier. The impact of nonlinearity and of dispersion was minimized by the low power level and the limited bandwidth of pulses.