Selective tuning of high-Q silicon photonic crystal nanocavities via   laser-assisted local oxidation
  We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 mm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ~ 30 mW laser powers. Over this tuning range, the cavity Q decreases from 3.2\times10^5 to 1.2\times10^5. Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation. 
Charlton J. Chen, Jiangjun Zheng, Tingyi Gu, James F. McMillan,   Mingbin Yu, Guo-Qiang Lo, Dim-Lee Kwong, and Chee Wei Wong
physics.optics