Enhanced optical axial confinement in asymmetric microtube cavities rolled up from circular-shaped nanomembranes

Asymmetric cone-like microtube cavities have been fabricated by unevenly rolling-up prestrained SiO/SiO2 circular-shaped nanomembranes. Spatially localized axial resonant modes are obtained due to an axial confinement mechanism that is defined by the variation of the tube radius and windings along the tube axis. A theoretical model is applied to quantitatively explain and confirm our experimental results. (C) 2012 Optical Society of America