High-index sensitivity of surface mode in photonic crystal hetero-slab-edge microcavity

We introduce a photonic crystal hetero-slab-edge microcavity design with surface mode, which is beneficial for optical index sensing. The simulated index sensitivity (R(n)) as high as 675 nm per refractive index unit (nm/RIU) variation is obtained with slab thickness of 180 nm. In experiments, single surface mode lasing action from a real device is observed. Based on the surface mode in this microcavity, high experimental R(n) value of 625 nm/RIU is achieved by detecting index variation in a CO(2) chamber with different gas pressures.