Optical properties of rolled-up tubular microcavities from shaped nanomembranes

Tubular optical microcavities have been fabricated by releasing prestressed SiO/SiO2 bilayer nanomembranes from polymer sacrificial layers, and their geometrical structure is well controlled by defining the shape of nanomembranes via photolithography. Optical measurements at room temperature demonstrate that resonant modes of microtubular cavities rolled up from circular shapes can be tuned in peak energy and relative intensity along the tube axes compared to those from square patterns. The resonant modes shift to higher energy with decreasing number of tube wall rotations and thickness, which fits well to finite-difference time-domain simulations. Polarization resolved measurements of the resonant modes indicate that their polarization axes are parallel to the tube axis, independent of the polarization of the excitation laser.