Unpolarized H1 photonic crystal nanocavities fabricated by stretched lattice design

We investigate the factors that affect the mode splitting in H1 planar photonic crystal cavities and hence demonstrate unpolarized emission with a high quality factor. Finite difference time domain simulations show that systematic errors in the fabrication process such as hole shape and period lift the degeneracy of the orthogonally polarized fundamental modes. By intentionally stretching the photonic crystal lattice in one direction, we show that the wavelength and mode splitting can be tuned to compensate for such fabrication errors. By using this technique, we demonstrate unpolarized emission at 951 nm with a quality factor of ∼4500.