Ultra Fast Nonlinear Optical Tuning of Photonic Crystal Cavities
  We demonstrate fast (up to 20 GHz), low power (5 $\mu W$) modulation of photonic crystal (PC) cavities in GaAs containing InAs quantum dots. Rapid modulation through blue-shifting of the cavity resonance is achieved via free carrier injection by an above-band picosecond laser pulse. Slow tuning by several linewidths due to laser-induced heating is also demonstrated. 
Ilya Fushman, Edo Waks, Dirk Englund, Nick Stoltz, Pierre Petroff,   Jelena Vuckovic