All-photonic, dynamic control of optical path length in a silica sphere resonator

We demonstrate dynamic control of the optical path length for probe light in a spherical dielectric resonator simply by multiplexing intense control light of another color and adjusting its wavelength. The fractional change in the path length, monitored by the resonance wavelengths of whispering gallery modes of the probe light, was nearly equal to the fractional change in the wavelength of the control light. The control was effective in both increasing and decreasing the wavelength, but the weaker the control light or the faster the wavelength change, the narrower the range of control.