Figure 4 - Dynamic tuning of the photon lifetime of a photonic-crystal nanocavity.

Output waveform of a Q=2.710⁵ waveguide-width-modulated cavity measured using a digital sampling oscilloscope with a fast InGaAs detector. The red curve shows the ring-down waveform of this cavity where the photon lifetime is 250 ps. The black curve is the ring-down waveform when the cavity is irradiated with a 2-ps pump pulse at 800 nm and t=350 ps to generate carriers. The decay immediately after the pump pulse is 30 ps, which is close to the temporal resolution of the sampling oscilloscope. We roughly estimate that the optical pumping energy absorbed in the cavity volume is 12 fJ.