title: Square lattice photonic crystal point-shifted nanocavity with lowest-order whispering-gallery mode.
abstract: We propose a point-shifted nanocavity based on square lattice photonic crystal, which sustains a lowest-order whispering-gallery (WG) mode. In simulation, the optimized WG mode (quality (Q) factor approximately 14,000) in point-shifted nanocavity can be with smaller mode volume (approximately 5.5(lambda/2n)(3)) but larger nano-post tolerance than those in single-defect cavity design. From well-fabricated device, single WG mode lasing with measured Q factor of 4,100 and low threshold of 160 microW is obtained. Besides, we also observe the changed polarization of WG mode due to modal symmetry breaking caused by the presence of a nearby dielectric nano-particle, which would be useful in sensing molecule binding or attaching for bio-chemical applications.
authors.affiliation: Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Rm. 415 CPT Building, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan. ricky.eo94g@nctu.edu.tw
authors.forename: Tsan-Wen
authors.initials: TW
authors.lastname: Lu
authors.forename: Pin-Tso
authors.initials: PT
authors.lastname: Lin
authors.forename: Kuan-Un
authors.initials: KU
authors.lastname: Sio
authors.forename: Po-Tsung
authors.initials: PT
authors.lastname: Lee